Dr. Jeff Masters' WunderBlog

The bizarrely active hurricane season of 2012 draws to a close

By: JeffMasters, 16:50 GMT le 30 novembre 2012

The long and highly destructive hurricane season of 2012 has finally drawn to a close. The hurricane season of 2012 will long be remembered for spawning Hurricane Sandy--a freakish storm that was the largest, most powerful, and second most destructive Atlantic hurricane on record. But this year's hurricane season had a number of unique attributes, making it one of the most bizarre seasons I've witnessed. Despite featuring a remarkable nineteen named storms--tied for the third highest total since record keeping began in 1851--this year's hurricane season had just one major hurricane. That storm was Hurricane Michael, which stayed at Category 3 strength for a scant six hours. This is the least number of major hurricanes in a season since the El Niño year of 1997, which had only Category 3 Hurricane Erika. There were no Category 4 or 5 hurricanes in 2012, for just the 3rd time since the active hurricane period we are in began in 1995. The only two other years since 1995 without a Category 4 or stronger hurricane were the El Niño years of 2006 and 1997. Both of those seasons had around half the number of named storms of 2012--nine in 2006, and eight in 1997. The relative lack of strong storms in 2012 helped keep the Accumulated Cyclone Energy (ACE) down to 128, about 30% above average.


Figure 1. Hurricane Sandy at 10:10 am EDT October 28, 2012. Image credit: NASA/GSFC.

A near-average year for number of tropical cyclones hitting the U.S.
Since the active hurricane period we've been in began in 1995, the U.S. has averaged getting hit by 4 named storms per year, with an average of 1.7 of these being hurricanes, and 0.6 being major Category 3 and stronger hurricanes. This year, we were hit by 3 named storms (Beryl, Debby, and Isaac). One of these was a hurricane (Isaac). Sandy didn't count as a hurricane strike on the U.S., since it transitioned to an extratropical cyclone a few hours before landfall. No major hurricanes hit the U.S., making 2012 the 7th consecutive year without a major hurricane strike. The only other time we've had a streak that long occurred between 1861 - 1868, during the decade of the Civil War.


Figure 2. Vertical instability over the tropical Atlantic in 2004 - 2012 (blue line) compared to average (black line.) The instability is plotted in °C, as a difference in temperature from near the surface to the upper atmosphere (note that the same scale is not used in all the plots, making the black climatological line appear different, when it is really the same for each plot.) Thunderstorms grow much more readily when vertical instability is high. Instability was near average during the August - October peak of hurricane season in 2004 - 2009, but was much lower than average during the hurricane seasons of 2010 - 2012. There was an unusual amount of dry, sinking air in the tropical Atlantic during 2010 - 2012, and the resulting low atmospheric instability reduced the proportion of tropical storms that have intensified into hurricanes. Vertical instability from 2004 - 2011 is taken from NOAA/RAMMB and for 2012 from NOAA/SSD.

Unusually stable air over the Tropical Atlantic in 2012
For the third consecutive hurricane season, 2012 featured an unusual amount of dry, sinking air over the tropical Atlantic and Caribbean Sea. Due to warmer-than-average sea surface temperatures and an active African Monsoon that generated plenty of African waves, a remarkably high number of tropical storms managed to form, but the unusually stable air in the hurricane genesis regions made it difficult for the storms to become strong. When we did see storms undergo significant intensification, it tended to occur outside of the tropics, north of 25°N, where there was not as much dry, sinking air (Sandy's intensification as it approached landfall in Cuba was an exception to this rule.) If we look at the last nine hurricane seasons (Figure 2), we can see that the hurricane seasons of 2010, 2011, and 2012 all featured similar levels of highly stable air over the tropical Atlantic. This is in marked contrast to what occurred the previous six years. The past three seasons all featured a near-record number of named storms (nineteen each year), but an unusually low ratio of strong hurricanes. Steering patterns the past three years also acted to keep most of the storms out to sea. Is this strange pattern something we'll see more of, due to climate change? Or is it mostly due to natural cycles in hurricane activity? I don't have any answers at this point, but the past three hurricane seasons have definitely been highly unusual in a historical context. I expect the steering currents to shift and bring more landfalling hurricanes to the U.S. at some point this decade, though.


Figure 3. Sea water floods the Ground Zero construction site at the World Trade Center, Monday, Oct. 29, 2012, in New York City. Image credit: AP.

Most notable events of the Hurricane Season of 2012
Hurricane Sandy was truly astounding in its size and power. At its peak size, twenty hours before landfall, Sandy had tropical storm-force winds that covered an area nearly one-fifth the area of the contiguous United States. Since detailed records of hurricane size began in 1988, only one tropical storm (Olga of 2001) has had a larger area of tropical storm-force winds, and no hurricanes has. Sandy's area of ocean with twelve-foot seas peaked at 1.4 million square miles--nearly one-half the area of the contiguous United States, or 1% of Earth's total ocean area. Most incredibly, ten hours before landfall (9:30 am EDT October 30), the total energy of Sandy's winds of tropical storm-force and higher peaked at 329 terajoules--the highest value for any Atlantic hurricane since at least 1969. This is 2.7 times higher than Katrina's peak energy, and is equivalent to five Hiroshima-sized atomic bombs. At landfall, Sandy's tropical storm-force winds spanned 943 miles of the the U.S. coast. No hurricane on record has been wider; the previous record holder was Hurricane Igor of 2010, which was 863 miles in diameter. Sandy's huge size prompted high wind warnings to be posted from Chicago to Eastern Maine, and from Michigan's Upper Peninsula to Florida's Lake Okeechobee--an area home to 120 million people. Sandy's winds simultaneously caused damage to buildings on the shores of Lake Michigan at Indiana Dunes National Lake Shore, and toppled power lines in Nova Scotia, Canada--locations 1200 miles apart!


Figure 4. Hurricane Isaac lit up by moonlight as it spins towards the city of New Orleans, LA, on August 26, 2012. The Suomi National Polar-orbiting Partnership (NPP) satellite captured these images with its Visible Infrared Imaging Radiometer Suite (VIIRS). The "day-night band" of VIIRS detects light in a range of wavelengths from green to near-infrared and uses light intensification to enable the detection of dim signals. Image Credit: NASA/NOAA, Earth Observatory.

Hurricane Isaac hit Louisiana as a Category 1 hurricane with 80 mph winds on August 28, but the storm's massive wind field brought a storm surge characteristic of a Category 2 hurricane to the coast. A storm surge of 11.1 feet was measured at Shell Beach, LA and higher surges were reported in portions of Louisiana. Fortunately, the new $14.5 billion upgrade to the New Orleans levee system kept the city dry. Isaac killed 9 people in the U.S., and 29 in the Caribbean.

Hurricane Ernesto hit Mexico's Yucatan Peninsula as a Category 1 hurricane with 85 mph winds on August 7. The storm killed 12 and did at least $250 million in damage.

Tropical Storm Debby formed on June 23, the earliest formation date on record for the season's 4th storm. The previous record was Dennis, on July 5, 2005. Debby killed seven and did over $300 million in damage, but helped relieve drought conditions over Northern Florida and Southern Georgia.

Tropical Storm Beryl, which made landfall on May 28 near Jacksonville Beach, FL with 70 mph winds, was the strongest tropical storm to make landfall in the U.S. prior to June 1. Beryl killed two but did minimal damage.

Nadine lasted for 21.75 days as a named storm, the 5th longest-lasting tropical storm in the Atlantic basin.

It was the 3rd year in a row with 19 named storms.

No named storms existed during the month of July and November, but we still managed big numbers.

Only 7 seasons have had more hurricanes than 2012.

The season had two named storm before the official June 1 start of hurricane season, only the 3rd time that has occurred.

Eight named storms formed in August, which tied 2004 for the most to form in that month.

Typhoon Bopha a threat to the Philippines
In the Western Pacific, where typhoon season commonly brings several storms in December, we have impressive Typhoon Bopha. Bopha is expected to head west-northwest and intensify over the weekend, potentially arriving in the Philippines on Tuesday as a powerful Category 3 typhoon. Bopha formed at an unusually low latitude for a tropical cyclone--near 4°N. Storms forming that close to the Equator don't get much help from the Earth's spin to get spinning, and it is rare to see a tropical cyclone forming southwards of 5°N.

The Colorado State University hurricane forecast team, led by Phil Klotzbach and Bill Gray, has a more in-depth summary of the 2012 hurricane season.

Jeff Masters

Hurricane

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Nineteen Atlantic tropical storms 3 consecutive years: a very rare event

By: JeffMasters, 16:13 GMT le 28 novembre 2012

The 2012 Atlantic hurricane season closes this Friday with another top-five tally for named storms--nineteen. This is the third consecutive year with nineteen named storms in the Atlantic, which is a remarkable level of activity for a three-year period. The closest comparable three-year period of activity occurred during 2003 - 2004 - 2005, when each season had fifteen-plus named storms. Since 1851, only two seasons--2005 (28 named storms) and 1933 (20 named storms)--have been busier than 2010, 2011, and 2012.


Figure 1. Preliminary tracks of the nineteen named storms from 2012. Image credit: National Hurricane Center.

How rare are 3 consecutive top-five hurricane seasons for named storms?
It is tremendously rare to get three consecutive top-five years in a database with a 162-year record. This would occur randomly just once every 34,000 years--assuming the database were unbiased, the climate were not changing, and a multi-year climate pattern favorable for active seasons were not present. However the database IS biased, the climate IS changing, and we have been in an active hurricane period that began in 1995. So, which of these factors may be responsible for recording three consecutive years with nineteen named storms? It is well-known that prior to the arrival of geostationary satellites in December 1966 and aircraft hurricane reconnaissance in 1945 that tropical storms in the Atlantic were under-counted. Landsea et al. (2004) theorized that we missed up to six named storms per year between 1851 - 1885, and up to four between 1886 - 1910. Landsea (2007) estimated the under-count to be 3.2 named storms per year between 1900 - 1965, and 1.0 per year between 1966 - 2002. Other studies have argued for lower under-counts. So, if we assume the highest under-counts estimated by Landsea et al. (2004) and Landsea (2007), here would be the top ten busiest Atlantic hurricane seasons since 1851:

2005: 28
1887: 25
1933: 23
1995: 20
2012, 2011, 2010, 1969, 1936: 19

So, 2012, 2011, and 2010 would still rank as top-five busiest seasons since 1851, but the odds of having three consecutive seasons with nineteen named storms would drop from a 1-in-34,000 year event to "only" a 1-in-5800 year event. More recently, Landsea et al. (2010) showed that the increasing trend in North Atlantic tropical storm frequency over the past 140 years was largely due to the increasing trend in short‐lived storms (storms lasting 2 days or less, called “shorties”), after the 1940s (Figure 2, top). They did not detect a significant increasing trend in medium‐ to long‐lived storms lasting more than 2 days. They wrote that “while it is possible that the recorded increase in short‐duration TCs [tropical cyclones] represents a real climate signal, we consider it is more plausible that the increase arises primarily from improvements in the quantity and quality of the observations, along with enhanced interpretation techniques.” Villarini et al. (2011), in a paper titled, "Is the recorded increase in short-duration North Atlantic tropical storms spurious?", agreed. They attempted to correlate increases in tropical Atlantic sea surface temperatures in recent decades to the increase in short-lived Atlantic tropical storms, and were unable to do so. They wrote: using statistical methods combined with the current understanding of the physical processes, we are unable to find support for the hypothesis that the century‐scale record of short‐lived tropical cyclones in the Atlantic contains a detectable real climate signal. Therefore, we interpret the long‐term secular increase in short‐duration North Atlantic tropical storms as likely to be substantially inflated by observing system changes over time. These results strongly suggest that studies examining the frequency of North Atlantic tropical storms over the historical era (between the 19th century and present) should focus on storms of duration greater than about 2 days. So, let's do that. If we look during the past three hurricane seasons at how many "shorties" were observed, we see that a large number that stayed at tropical storm strength for two days or less: six storms in 2010, six in 2011, and seven in 2012. This leaves the hurricane seasons of 2010, 2011, and 2012 with twelve to thirteen tropical storms that lasted more than two days. This doesn't stand out that much when looking at trends since 1878 (Figure 2, bottom); there are now 25 years in the 135-year record with twelve or more long-lived tropical cyclones. However, there are no previous occurrences of three consecutive years with at least twelve long-lived tropical storms, so 2010, 2011, and 2012 still represent an unprecedented level of tropical storm activity in the historical record, and we would expect such an event to occur randomly about once every 157 years. That's a pretty rare event, and it is possible that climate change, combined with the fact we are in an active hurricane period that began in 1995, contributed to this rare event.


Figure 2. Atlantic tropical cyclones between 1878 - 2012 that spent two days or less at tropical storm strength (top) and more than two days at tropical storm strength or hurricane strength (bottom.) Figure updated from Villarini, G., G. A. Vecchi, T. R. Knutson, and J. A. Smith (2011), "Is the recorded increase in short-duration North Atlantic tropical storms spurious?", J. Geophys. Res., 116, D10114, doi:10.1029/2010JD015493.

References
Landsea, C. W., C. Anderson, N. Charles, G. Clark, J. Dunion, J. Fernandez‐Partagas, P. Hungerford, C. Neumann, and M. Zimmer (2004), "The Atlantic hurricane database re‐analysis project: Documentation for 1851–1910 alterations and additions to the HURDAT database," in Hurricanes and Typhoons ‐ Past, Present, and Future, edited by R. J. Murnane and K. B. Liu, pp. 178–221, Columbia Univ. Press, New York.

Landsea, C. W., (2007), "Counting Atlantic tropical cyclones back to 1900," Eos, 88(18), 197-202.

Villarini, G., G. A. Vecchi, T. R. Knutson, and J. A. Smith (2011), "Is the recorded increase in short-duration North Atlantic tropical storms spurious?", J. Geophys. Res., 116, D10114, doi:10.1029/2010JD015493

Jeff Masters

Hurricane

Updated: 16:16 GMT le 28 novembre 2012

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Damaging Katrina-level storm surges are twice as likely in warm years

By: JeffMasters, 17:22 GMT le 26 novembre 2012

Perhaps the most stunning images in the wake of Hurricane Sandy were the sight of the roller coaster from the Casino Pier in Seaside Heights, New Jersey lying in the Atlantic Ocean. The images reminded us that hurricane storm surges are capable of causing tremendous destruction along the coast, and one of the main concerns on how global warming might affect hurricanes is the potential for stronger hurricanes to create larger storm surges. We expect that global warming should make the strongest hurricanes stronger, since hurricanes are heat engines that take heat energy out of the ocean and converts it to wind energy. These stronger winds will be capable of piling up higher storm surges. However, it is controversial whether or not we have observed an increase in the strongest hurricanes, since hurricane winds are hard to observe. Our long-term hurricane data base is generally too low in quality and covers too short a period of time to make very good estimates of how climate change may be affecting hurricane winds. However, a new 2012 paper, "Homogeneous record of Atlantic hurricane surge threat since 1923" by Grinsted et al., looked at storm surge data from six tide gauges along the U.S. coast from Texas to New Jersey, and concluded that the number of moderately large hurricane and tropical storm surge events has increased since 1923. Moderately large storm surge events are on pace to nearly double by the year 2100, compared to 20th century levels. Moreover, 1-in-9 year to 1-in-30 year Katrina-level storm surge events are twice as likely to occur in warm years compared to cool years, and thus global warming may be able to dramatically increase the frequency of highly damaging extreme storm surge events. Since sea level is steadily rising due to global warming, these future storm surges will also be riding in on top of an elevated ocean surface, and will thus be able to do even greater damage than in the past. Expect to see many more shocking storm surge damage photos in the coming decades, unless we wise up, retreat from areas highly vulnerable to storm surge, and invest in increased shoreline protection measures.


Figure 1. The Casino Pier in Seaside Heights, N.J. taken during a search and rescue mission by 1-150 Assault Helicopter Battalion, New Jersey Army National Guard on Oct. 30, 2012. Image credit: U.S. Air Force photo by Master Sgt. Mark C. Olsen.


Figure 2. Top: Observed long-term frequency of moderately large storm surge events from hurricanes and tropical storms measured at six tide gauges along the U.S. East Coast (inset map). The thick line is a 5-year moving average. These type of surge events occurred an average of 5.4 times/year between 1923 - 2008, and are on pace to increase to 9.5 events per year by 2100. Bottom: Departure of Earth's annual mean surface temperature from average, shaded to show warmer and colder than median temperatures. Large storm surge events increase in probability during warmer than average years. Image credit: Grinsted et al. 2012, "A homogeneous record of Atlantic hurricane surge threat since 1923."

Using storm surge to evaluate damage normalization studies
Damage from landfalling storms can be used to estimate if hurricanes are growing stronger with time, but damage estimates must first be corrected to account for changes in wealth and population over time. A 2008 study by Pielke et al. found that although hurricane damages had been doubling every ten years in recent decades, there were no increases in normalized hurricane damages in the U.S. from 1900 - 2005. They used census and economic data to adjust for how increases in populations and wealth may have affected hurricane damages over time. However, Grinsted et al. (2012) questioned whether or not this was done correctly. They found that storm surge heights of U.S. hurricanes and tropical storms correlated very well with metrics that looked at storm intensity, when looking at many decades of data to see long-term trends. However, the researchers found that while short-term trends in normalized hurricane damage estimated by Pielke et al. (2008) did correlate well historical storm surges, these normalized damages had poor correlation with the storm surge record, when looking at decades-long time scales. This implies that the corrections were biased. Dr. Stephan Lewandowsky of the University of Western Australia makes the case that efforts such as the one done by Pielke et al. (2008) to normalize disaster losses are probably biased too low, since they only look at factors that tend to increase disaster losses with time, but ignore factors that tend to decrease disaster losses. These ignored factors include improvements in building codes, better weather forecasts allowing more preparation time, and improved fire-fighting ability. He writes, "Most normalization research to date has not accounted for those variables because they are extremely difficult to quantify. (And most researchers have been at pains to point that out; e.g., Neumayer & Barthel, 2011, pp. 23-24.) In effect, normalization research to date largely rests on the oddly inconsistent pair of assumptions that (a) we have built up enormous wealth during the 20th century but (b) did so without any technological advance whatsoever." Grinsted et al. (2012) suggest that it may be possible to use their storm surge data to correct biased hurricane damage estimates, though. Take home message: studies showing no increase in normalized damage from storms have high uncertainty, and it is possible that higher economic damages due to stronger hurricanes are indeed occurring.

References
Grinsted, A., J. C. Moore, and S. Jevrejeva, 2012, "A homogeneous record of Atlantic hurricane surge threat since 1923," PNAS 2012, doi:10.1073/pnas.1209542109

Pielke et al., 2008, "Normalized Hurricane Damage in the United States: 1900–2005", Natural Hazards Review, Volume 9, Issue 1, pp. 29-42.

Links
In this remarkable home video, 15-year-old Christofer Sochacki captures the evening high tide on the day Superstorm Sandy struck Union Beach, New Jersey. The later part of the video shows how high waves on top of a 8-foot storm surge can lead to a punishing assault on beach-front structures.

Jeff Masters

Hurricane Climate Change

Updated: 23:45 GMT le 26 novembre 2012

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A tranquil and record-warm Thanksgiving for much of the U.S.

By: JeffMasters, 17:35 GMT le 23 novembre 2012

Celebrations of the Thanksgiving holiday in the United States in 2012 were aided by some of the most tranquil travel weather ever seen on what is America's busiest travel week. Unusually warm and precipitation-free conditions prevailed over almost the entire nation on Wednesday and Thursday, with many locations in the Midwest reporting their warmest Thanksgiving Day on record. At least three cities set records for their warmest temperature ever recorded so late in the year: Valentine, Nebraska (76° on Wednesday); Rochester, Minnesota (70° on Wednesday); and Sault Ste. Marie, Michigan (65° on Thursday.) While the quiet weather was a boon for travelers, the lack of rain in the Midwest allowed the nation's worst drought since 1954 to expand; the U.S. Drought Monitor reported that the area of the contiguous U.S. covered by moderate or greater drought expanded by 1% to 60% this week. This reversed a seven-week trend of slowly decreasing drought that began on September 25 and extended until November 13, when the area covered by drought declined from 65% to 59%. The latest ten-day forecasts from the GFS and ECMWF models show much below average chances of precipitation across more 90% of the U.S., including the drought regions. These dry conditions will allow the drought to expand over the next two weeks, and potentially cover 65% of the contiguous U.S. again by mid-December. The next chance for significant rains in excess of one inch in the Midwest will not occur until December 2, at the earliest. The lack of rain will potentially cause serious trouble for barge traffic on the Mississippi River by December 10, when the river may fall below the level of -5 feet at St. Louis needed to allow barges to not scrape bottom.


Figure 1. This week's U.S. Drought Monitor shows 60% of the contiguous U.S. was in moderate or greater drought.


Figure 2. Predicted 8-day precipitation amounts from the 06Z (1 am EST) November 23, 2012 run of the GFS model. For the 8-day period ending on Saturday, December 1, only the Northwest Coast, Central Gulf Coast, and portions of the Tennessee Valley are predicted to receive rains in excess of one inch. Image credit: NOAA.

Quiet in the Atlantic
There are no threat areas in the Atlantic to discuss today, and none of the reliable models is forecasting tropical cyclone development between now and the Friday, November 30 official end of hurricane season. I wouldn't dismiss the possibility of one more named storm forming in December in the middle Atlantic between Bermuda and Puerto Rico, but late-season storms forming in that location rarely affect land.

Have a great holiday weekend, everyone!

Jeff Masters

Drought Heat

Updated: 20:15 GMT le 25 novembre 2012

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Lessons on Persuasion from Jesus, Shakespeare, Lincoln, and Lady Gaga: a Book Review

By: JeffMasters, 16:46 GMT le 21 novembre 2012

With a name like "Language Intelligence: Lessons on Persuasion from Jesus, Shakespeare, Lincoln, and Lady Gaga", a book with a title like that compels one to pick it up and see what the heck the author is talking about. And Joe Romm's new book on how to communicate doesn't disappoint--it's a thoughtful and compelling look at the techniques used by some of history's great communicators to help persuade. Joe Romm is author of the climateprogress.org blog, the most visited climate change blog on the Internet, and the main blog that I use to stay current on climate change and energy news. Romm defines Language Intelligence as "the ability to convince people of something both intellectually and emotionally, at both a conscious and unconscious level." He goes on to say, "If facts were sufficient to persuade people, then experts in science would rule the world. But facts are not, and scientists do not. We filter out all the facts that do not match our views." At the heart of great communication lies great story telling, and Romm give us these tips on how to tell a story people will want to read:

- Write a great headline: Newspaper readers read 56% of the headlines, but only 13% of the stories are at least half-read. Headlines are even more important on-line, since they are what show up on Google searches and tweets. An example of one the most re-tweeted headlines Romm used in 2011: "Mother Nature is Just Getting Warmed Up: June 2011 Heat Records Crushing Cold Records by 13 to 1" (Romm uses a pun and personification to help create an eye-catching headline.)

- Short words are the best words.

- Slogans sell.

- If you don't repeat, you can't compete. Repetition and rhyming help people remember your message.

- The golden rule of speech-making is: "Tell 'em what you're going to tell 'em; tell 'em; then tell 'em what you told 'em."

- Repeated distortions and smears are as effective as repeated truths, so beware of these sorts of attacks.

- If you want to de-bunk a myth, you need to focus on stating the truth, not repeating the myth.

- If you want to be more noticed and remembered, use more figures of speech (metaphors.) Examples of metaphors I've used include comparing our melting Arctic to the attic of a house that is on fire (Earth's attic is on fire: Arctic sea ice bottoms out at a new record low) and comparing the impact of global warming on extreme weather to the impact steroids have on a baseball slugger (Extreme events of 2011: climate change a major factor in some, but not all).

- Create an extended metaphor when you have a big task at hand. Countless books and articles underscore that extended metaphors are at the core of human thinking.



Video 1. National Center for Atmospheric Research scientist Dr. Jerry Meehl uses a metaphor to explain how climate change's impact on extreme weather is similar to how steroids affect a baseball slugger's ability to hit a ball out of the park.

At 183 pages, the book only took me about two hours to read, and I was very glad I did. It was very entertaining and informative, and anyone involved in public communication can learn from this book. I give it my highest rating: four stars out of four. Language Intelligence: Lessons on Persuasion from Jesus, Shakespeare, Lincoln, and Lady Gaga is $9.67 from Amazon.com.

Have a great Thanksgiving Holiday, everyone, and I'll have a new post for you on Friday.

Jeff Masters

Book and Movie Reviews

Updated: 16:54 GMT le 21 novembre 2012

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Great U.S. Drought of 2012 to Last Into Spring of 2013

By: JeffMasters, 16:44 GMT le 19 novembre 2012

Beneficial rains over portions of the Central U.S. during the past week put a slight dent in the nation's worst drought since 1954. According to the latest U.S. Drought Monitor, the amount of the contiguous U.S. in moderate to extreme drought declined last week to 59%, down from the 65% peak of September 25, 2012. However, the intense drought is likely to persist through the winter, and its already heavily impacting the Winter Wheat growing season, which began in October. NOAA's latest State of the Drought product advised that the Palmer Drought Severity Index (PDSI) for the Primary Hard Red Winter Wheat area reached the lowest value since the 1950s in October. The persistent drought is also a major problem for Mississippi River navigation. According to a November 17 AP story, the Mississippi is so low that if it drops another five feet, barge traffic may shut down from St. Louis to the confluence of the Ohio River at Cairo, IL. The Army Corps of Engineers plans to lower the level of the Mississippi by 2 - 3 feet over the next few weeks, due to the need to conserve water in the upper Missouri River basin. The latest two-week forecast from the GFS model predicts very little in the way of precipitation over the nation's drought-stricken region over the next ten days, which is good for holiday travel, but will worsen the drought.



Figure 1. The latest seasonal drought outlook from NOAA's Climate Prediction Center calls for drought conditions to persist across most of the nation's drought areas through the winter of 2012 - 2013.


Figure 2. Amount of precipitation needed to bust drought conditions over the U.S., according to NOAA's Climate Prediction Center. Southeastern Oklahoma and Northwest Arkansas need the most rain, at least 12 - 15".

Long-term drought outlook
NOAA's Climate Prediction Center predicts that neutral El Niño conditions will prevail this winter, and has cancelled their El Niño watch. The expected neutral El Niño conditions have prompted the Climate Prediction Center to forecast equal chances of wetter or drier than average conditions across the heart of the drought region during the coming winter. In general, droughts are more likely in the Central U.S. when warmer than average ocean temperatures prevail in the tropical Atlantic, and cooler than average ocean temperatures are present in the tropical Eastern Pacific (La Niña-like conditions.) Currently, we do have warmer than average ocean temperatures in the tropical Atlantic, but also in the equatorial tropical Pacific (0.5°C above average as of November 19), so this is a lower-risk scenario for Central U.S. drought than we had during the winter of 2011 - 2012. However, considering that most of the nation's drought regions need 6 - 15" of precipitation to pull them out of drought, the Great Drought of 2012 is likely to linger into the spring of 2013.


If you missed it, Sunday night's showing of renowned documentary film maker Ken Burns' new film, "The Dust Bowl" was a fascinating look back at America's greatest drought. I was most struck by the accounts of the great dust storms that swept through the Plains, which grew in frequency and ferocity though the mid-1930s. Part one closed with a song by folk singer Woody Guthrie singing "So Long, It's Been Good to Know You." Guthrie lived through the great dust storms of the Dust Bowl, when the dust storms grew so violent and the skies so black that people thought the end of the world was at hand. Part two of "The Dust Bowl", "Reaping the Whirlwind", shows tonight (Monday night), November 19, from 8 - 10 pm. It opens with Woody Guthrie singing "The Great Dust Storm", about the notorious "Black Sunday" dust storm of April 14, 1935--America's worst dust storm in recorded history.

Lyrics of Woody Guthrie's, "So Long, It's Been Good to Know You"
I've sung this song, but I'll sing it again,

Of the place that I lived on the wild windy plains,

In the month called April, county called Gray,

And here's what all of the people there say:

CHORUS: So long, it's been good to know yuh;

So long, it's been good to know yuh;

So long, it's been good to know yuh.

This dusty old dust is a-gettin' my home,

And I got to be driftin' along.

A dust storm hit, an' it hit like thunder;

It dusted us over, an' it covered us under;

Blocked out the traffic an' blocked out the sun,

Straight for home all the people did run,
Singin':

CHORUS

We talked of the end of the world, and then

We'd sing a song an' then sing it again.

We'd sit for an hour an' not say a word,

And then these words would be heard:

CHORUS

Sweethearts sat in the dark and sparked,

They hugged and kissed in that dusty old dark.

They sighed and cried, hugged and kissed,

Instead of marriage, they talked like this:

"Honey..."

CHORUS

Now, the telephone rang, an' it jumped off the wall,

That was the preacher, a-makin' his call.

He said, "Kind friend, this may the end;

An' you got your last chance of salvation of sin!"

The churches was jammed, and the churches was packed,

An' that dusty old dust storm blowed so black.

Preacher could not read a word of his text,

An' he folded his specs, an' he took up collection,

Said:

So long, it's been good to know yuh;

So long, it's been good to know yuh;

So long, it's been good to know yuh.

This dusty old dust is a-gettin' my home,
And I got to be driftin' along.


Video 1. Woody Guthrie wrote several songs about the Dust Bowl. Here is a version of his "Dust Bowl Blues", illustrated by some remarkable video of Dust Bowl scenes from the 1930s.

Links:
My post on Lessons from 2012: Droughts, not Hurricanes, are the Greater Danger discussed how drought is our greatest threat from climate change.

Ricky Rood blogs about the Dust Bowl

Jeff Masters

Drought

Updated: 20:05 GMT le 26 novembre 2012

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Lessons from 2012: Droughts, not Hurricanes, are the Greater Danger

By: JeffMasters, 15:34 GMT le 16 novembre 2012

The colossal devastation and loss of life wrought by Hurricane Sandy makes the storm one of the greatest disasters in U.S. history. The storm and its aftermath have rightfully dominated the weather headlines this year, and Sandy will undoubtedly be remembered as the most notable global weather event of 2012. But shockingly, Sandy is probably not even the deadliest or most expensive weather disaster this year in the United States--Sandy's damages of perhaps $50 billion will likely be overshadowed by the huge costs of the great drought of 2012. While it will be several months before the costs of America's worst drought since 1954 are known, the 2012 drought is expected to cut America's GDP by 0.5 - 1 percentage points, said Deutsche Bank Securities this week. “If the U.S. were growing at 4 percent, it wouldn’t be as big an issue, but at 2 percent, it’s noticed,” said Joseph LaVorgna, the chief U.S. economist at Deutsche. Since the U.S. GDP is approximately $15 trillion, the drought of 2012 represents a $75 - $150 billion hit to the U.S. economy. This is in the same range as the estimate of $77 billion in costs for the drought, made by Purdue University economist Chris Hurt in August. While Sandy's death toll of 113 in the U.S. is the second highest death toll from a U.S. hurricane since 1972, it is likely to be exceeded by the death toll from the heat waves that accompanied this year's drought. The heat waves associated with the U.S. droughts of 1980 and 1988 had death tolls of 10,000 and 7,500 respectively, according to NOAA's National Climatic Data Center, and the heat wave associated with the $12 billion 2011 Texas drought killed 95 Americans. With July 2012 the hottest month in U.S. history, I expect the final heat death toll in the U.S. this year will be much higher than Sandy's death toll.


Figure 1. The top-ten list of most expensive U.S. weather-related disasters from NOAA's National Climatic Data Center (NCDC) is dominated by hurricanes and droughts. Three of the top five disasters are droughts. The numbers for Hurricane Sandy and the 2012 drought are preliminary numbers from media sources, and are not from NCDC.

Drought: civilization's greatest natural enemy
People fear storms, and spectacular and devastating storms like Hurricane Sandy and Hurricane Katrina have stirred more debate in the U.S. about taking action against climate change than any other weather event. But I argue that this attention is misplaced. Drought is our greatest enemy. Drought impacts the two things we need to live--food and water. The history of civilization is filled with tales of great storms that have killed thousands and caused untold suffering and destruction. But cities impacted by great storms inevitably recover and rebuild, often stronger than before. I expect that New York City, the coast of New Jersey, and other areas battered by Sandy will do likewise. But drought can crash civilizations. Drought experts Justin Sheffield and Eric Wood of Princeton, in their 2011 book, Drought, list more than ten civilizations and cultures that probably collapsed because of drought. Among them: The Mayans of 800 - 1000 AD. The Anasazi culture in the Southwest U.S. in the 11th - 12th centuries. The ancient Akkadian Empire in Mesopotamia. The Chinese Ming Dynasty of 1500 - 1730. When the rains stop and the soil dries up, cities die and civilizations collapse, as people abandon lands no longer able to supply them with the food and water they need to live.


Figure 2. Ruins of the Cliff Palace at Mesa Verde National Park in Colorado. Beginning in 1150 AD, North America experienced a 300-year drought called the Great Drought. This drought has often been cited as a primary cause of the collapse of the ancient Anasazi civilization in the Southwest U.S., and abandonment of places like the Cliff Palace.

The coming great droughts
We should not assume that the 21st century global civilization is immune from collapse due to drought. If we continue on our current path of ever-increasing emissions of carbon dioxide, the hotter planet that we will create will surely spawn droughts far more intense than any seen in recorded history, severely testing the ability of our highly interconnected global economy to cope. The coming great drought disasters will occur at a time when climate change is simultaneously creating record rainfall and flooding in areas that happen to be in the way of storms. Global warming puts more heat energy into the atmosphere. That means more more water will evaporate from the oceans to create heavier rains and make storms stronger, and there will be more heat energy to increase the intensity of heat waves and droughts. It all depends upon if you happen to lie on the prevailing storm track or not which extreme you'll experience. In the future, if you're not being cooked in a record drought, you're going to be washed away in a record flood. Just ask the residents of the Midwest. In 2011, residents of the Midwest endured the largest floods on record on their three great rivers--the Mississippi, Missouri, and Ohio. In 2012, the same region endured their worst drought since 1954, and a top-ten warmest summer.

The nation's top scientific research group, the National Research Council, released an 18-month study on November 9, 2012, titled, "Climate and Social Stress: Implications for Security Analysis". They stated: “It is prudent to expect that over the course of a decade some climate events--including single events, conjunctions of events occurring simultaneously or in sequence in particular locations, and events affecting globally integrated systems that provide for human well-being--will produce consequences that exceed the capacity of the affected societies or global system to manage and that have global security implications serious enough to compel international response.” In other words, states will fail, millions will suffer famine, mass migrations and war will break out, and national and international agencies will be too overwhelmed to cope. We were very lucky that the 2012 U.S. drought did not occur the year following the great 2010 Russian drought. That drought drove up food prices to the highest levels since 1992, and helped trigger social unrest that led to the "Arab Spring" revolts that overthrew multiple governments. Severe droughts in back-to-back years in major world grain-producing areas could cause unprecedented global famine and unrest, and climate change is steadily increasing the odds of this happening.


Figure 3. Black Sunday: On April 14, 1935 a "Black Blizzard" hit Oklahoma and Texas with 60 mph winds, sweeping up topsoil loosened by the great Dust Bowl drought that began in the early 1930s.

Learning from the past: the great Dust Bowl of the 1930s

"The clouds appeared and went away, and in a while they did not try anymore."
- Nobel Prize-winning author John Steinbeck in his 1939 classic, The Grapes of Wrath, describing the weather in Oklahoma during the great Dust Bowl drought of the 1930s.

No disaster in American history caused more suffering than the legendary Dust Bowl drought of the 1930s, as year after year of desperately dry conditions across the Great Plains dried out farmlands, forcing 2.5 million people to leave their homes and seek a better life elsewhere. At its peak in July 1934, drought conditions covered an astonishing 80% of the contiguous U.S., making it our largest drought ever recorded. The true cost of the drought is impossible to calculate, but the amount of government assistance paid out was $13 billion in today's dollars. The heat waves that accompanied the drought killed at least 5,000 people, making it one of the deadliest disasters in U.S. history. Fortunately, a repeat of the dust storms and hardships of the 1930s Dust Bowl are much less likely now, because we learned from our mistakes. In a 2009 paper titled, Amplification of the North American "Dust Bowl" drought through human-induced land degradation, a team of scientists led by Benjamin Cook of the Lamont-Doherty Earth Observatory explained the situation that led up to the Dust Bowl:

During the 1920s, agriculture in the United States expanded into the central Great Plains. Much of the original, drought-resistant prairie grass was replaced with drought-sensitive wheat. With no drought plan and few erosion-control measures in place, this led to large-scale crop failures at the initiation of the drought, leaving fields devegetated and barren, exposing easily eroded soil to the winds. This was the source of the major dust storms and atmospheric dust loading of the period on a level unprecedented in the historical record.

Improved farming practices adopted after the great Dust Bowl allowed the Midwest to endure the great multi-year drought of 1951 - 1954 without the kind of damage the Dust Bowl caused. Those improved farming practices, in combination with the development of improved drought-resistant grains, have helped keep the damages from the 2012 drought down. But climate change has the potential to bring far more severe droughts to the U.S. than anything seen in American history. The great drought of 2012 is a harbinger of the future, and we have a significant challenge to meet if we are to continue feeding the world in the face of intensifying droughts during the coming decades. We need to stop the unsustainable pumping of our aquifers, move even more aggressively to develop improved drought-resistant grains, and practice better water conservation if we are to avoid future Dust Bowl-scale tragedies.



Renowned documentary film maker Ken Burns debuts his new film, "The Dust Bowl", on PBS this Sunday and Monday, November 18 and 19, 2012, from 8 - 10 pm EST. Catch the trailer at pbs.org. It promises to be a fascinating and highly relevant story, told by one of America's great story-tellers. PBS is also airing a show on Hurricane Sandy, Inside the Megastorm, on NOVA on Sunday night November 18, at 7 pm. I helped them out this week with fact checking and graphics for the show.

Jeff Masters

Drought Climate Change Extreme Weather

Updated: 21:28 GMT le 16 novembre 2012

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October 2012: Earth's 5th warmest October on record

By: JeffMasters, 17:18 GMT le 15 novembre 2012

October 2012 was the globe's 5th warmest October on record, said National Oceanic and Atmospheric Administration's National Climatic Data Center (NCDC) today. NASA rated October 2012 the 2nd warmest October on record. Global temperature records begin in 1880. October 2012 global land temperatures were the 8th warmest on record, and global ocean temperatures were the 4th warmest on record. October 2012 was the 332nd consecutive month with global temperatures warmer than the 20th century average. The last time Earth had a below-average October global temperature was in 1976, and the last below-average month of any kind was February 1985. Global satellite-measured temperatures in October 2012 for the lowest 8 km of the atmosphere were 7th or 2nd warmest in the 34-year record, according to Remote Sensing Systems and the University of Alabama Huntsville (UAH), respectively. Wunderground's weather historian, Christopher C. Burt, has a comprehensive post on the notable weather events of October 2012 in his October 2012 Global Weather Extremes Summary.


Figure 1. Departure of temperature from average for October 2012, the 5th warmest October for the globe since record keeping began in 1880. Several regions around the globe were much warmer than average, including northeastern and southwestern North America, most of South America, northern Africa, southeastern Europe, southwestern Asia, and far eastern Russia. A heat wave brought record warmth to large areas of Brazil and Bolivia. Record heat was also present in southern India. It was cooler than average in parts of northern Siberia, Mongolia, and northern China along with much of central North America. Western Canada was much cooler than average. Image credit: National Climatic Data Center (NCDC) .

El Niño watch discontinued
Neutral El Niño conditions exist in the equatorial Pacific, where sea surface temperatures were 0.4°C above average as of November 12. NOAA's Climate Prediction Center (CPC) has cancelled their El Niño watch, and expects neutral El Niño conditions for the coming winter. Temperatures in the equatorial Eastern Pacific need to be 0.5°C above average or warmer to be considered an El Niño. El Niño conditions tend to bring cooler and wetter winter weather to the Southern U.S.


Figure 2. Arctic sea ice extent in October 2012 (thick black line) was the second lowest since satellite records began in 1979. Sea ice extent has sunk to the lowest values on record for this time of year during the first half of November. The previous record low occurred in 2007 (magenta line.) Image credit: National Snow and Ice Data Center (NSIDC) and meteomodel.pl.

Arctic sea ice falls to 2nd lowest October extent on record
Arctic sea ice extent during October reached its second lowest extent in the 35-year satellite record, behind 2007, according to the National Snow and Ice Data Center (NSIDC). Beginning in late October, Arctic sea ice extent began setting new daily record lows again, and it is very likely we will have a new monthly record low for the month of November. I have much more to say about this year's extraordinary loss of Arctic sea ice in my October 20, 2012 post, Earth's attic is on fire: Arctic sea ice bottoms out at a new record low.

Jeff Masters

Climate Summaries

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Nor'easter next week primarily a threat to North Carolina

By: JeffMasters, 14:54 GMT le 15 novembre 2012

A complex series of low pressure systems will affect the U.S. coast near North Carolina through early next week, and a powerful Nor'easter is expected to develop off the North Carolina coast on Monday, then move northeastwards out to sea. The storm will be too far from coastal areas of New Jersey and New York hard-hit by Sandy to cause more than minor coastal flooding, thankfully. However, high winds, heavy rain, and coastal flooding are expected to affect the coast of North Carolina beginning on Saturday, with the peak winds and greatest coastal flooding likely to occur on Sunday and Monday. Minor to moderate flooding will occur along much of the Northeast North Carolina coast, and coastal Highway 12 that connects the Outer Banks to the mainland will probably be cut. Hurricane Sandy pummeled the Outer Banks of North Carolina in late October, causing $13 million in damage. Sandy weakened or wiped out the protective dunes along a long section of coast, and caused significant damage to coastal Highway 12. As a result, all it takes is a high tide to cause overwash on this vital artery. The road was closed on Tuesday due to overwash during the high tide cycles, and requires a 4-wheel-drive vehicle to navigate it due to the extensive damage it has suffered over the past two weeks. Residents of the Outer Banks must take a 2-hour ferry ride to get to the mainland when Highway 12 is cut.


Figure 1. Coastal Highway 12 in North Carolina, which connects the Outer Banks to the mainland, as seen at 5:43 pm EST on Tuesday, November 13, 2012, near Rodanthe. Hurricane Sandy wiped out most of the protective dunes along the coast, allowing the ocean to directly pound the road during high tide. Image credit: North Carolina DOT.

All quiet in the Atlantic
The Atlantic is quiet, with no threat areas to discuss. None of the reliable computer models is predicting formation of a tropical cyclone during the coming seven days.

Jeff Masters

Hurricane Winter Weather

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Hurricane Sandy's huge size: freak of nature or climate change?

By: JeffMasters, 13:10 GMT le 13 novembre 2012

Hurricane Sandy was truly astounding in its size and power. At its peak size, twenty hours before landfall, Sandy had tropical storm-force winds that covered an area nearly one-fifth the area of the contiguous United States. Since detailed records of hurricane size began in 1988, only one tropical storm (Olga of 2001) has had a larger area of tropical storm-force winds, and no hurricanes has. Sandy's area of ocean with twelve-foot seas peaked at 1.4 million square miles--nearly one-half the area of the contiguous United States, or 1% of Earth's total ocean area. Most incredibly, ten hours before landfall (9:30 am EDT October 30), the total energy of Sandy's winds of tropical storm-force and higher peaked at 329 terajoules--the highest value for any Atlantic hurricane since at least 1969. This is 2.7 times higher than Katrina's peak energy, and is equivalent to five Hiroshima-sized atomic bombs. At landfall, Sandy's tropical storm-force winds spanned 943 miles of the the U.S. coast. No hurricane on record has been wider; the previous record holder was Hurricane Igor of 2010, which was 863 miles in diameter. Sandy's huge size prompted high wind warnings to be posted from Chicago to Eastern Maine, and from Michigan's Upper Peninsula to Florida's Lake Okeechobee--an area home to 120 million people. Sandy's winds simultaneously caused damage to buildings on the shores of Lake Michigan at Indiana Dunes National Lakeshore, and toppled power lines in Nova Scotia, Canada--locations 1200 miles apart!

Largest Atlantic tropical cyclones for area covered by tropical storm-force winds:

Olga, 2001: 780,000 square miles
Sandy, 2012: 560,000 square miles
Lili, 1996: 550,000 square miles
Igor, 2010: 550,000 square miles
Karl, 2004: 430,000 square miles



Figure 1. Hurricane Sandy’s winds (top), on October 28, 2012, when Sandy was a Category 1 hurricane with top winds of 75 mph (this ocean surface wind data is from a radar scatterometer on the Indian Space Research Organization’s (ISRO) Oceansat-2.) Hurricane Katrina’s winds (bottom) on August 28, 2005, when Katrina was a Category 5 hurricane with top winds of 175 mph (data taken by a radar scatterometer on NASA’s defunct QuickSCAT satellite.) In both maps, wind speeds above 65 kilometers (40 miles) per hour are yellow; above 80 kph (50 mph) are orange; and above 95 kph (60 mph) are dark red. The most noticeable difference is the extent of the strong wind fields. For Katrina, winds over 65 kilometers per hour stretched about 500 kilometers (300 miles) from edge to edge. For Sandy, winds of that intensity spanned an region of ocean three times as great--1,500 kilometers (900 miles). Katrina was able to generate a record-height storm surge over a small area of the Mississippi coast. Sandy generated a lower but highly destructive storm surge over a much larger area, due to the storm's weaker winds but much larger size. Image credit: NASA.

How did Sandy get so big?
We understand fairly well what controls the peak strength of a hurricane's winds, but have a poor understanding of why some hurricanes get large and others stay small. A number of factors probably worked together to create a "prefect storm" situation that allowed Sandy to grow so large, and we also must acknowledge that climate change could have played a role. Here are some possible reasons why Sandy grew so large:

1) Initial size of the disturbance that became Sandy was large
Sandy formed from an African tropical wave that interacted with a large area of low pressure that covered most of the Central Caribbean. Rotunno and Emanuel (1987) found that hurricanes that form from large initial tropical disturbances like Sandy did tend to end up large in size.


Figure 2. The initial disturbance that spawned Sandy, seen here on October 20, 2012, was quite large.

2) High relative humidity in Sandy's genesis region
The amount of moisture in the atmosphere may play an important role in how large a hurricane gets (Hill and Lackmann, 2009.) Sandy was spawned in the Caribbean in a region where the relative humidity was near 70%. This is the highest humidity we saw during 2012 during the formation of any Atlantic hurricane.

3) Passage over Cuba
Sandy struck Cuba as an intensifying Category 2 hurricane with 110 mph winds. While the core of the storm was over Cuba, it was cut off from the warm ocean waters surrounding Cuba. Most of Sandy's large circulation was still over the ocean, though, and the energy the storm was able to extract from the ocean went into intensifying the spiral bands over water. When Sandy's core re-emerged over water, the hurricane now had spiral bands with heavier thunderstorm activity as a result of the extra energy pumped into the outer portion of the storm during the eye's passage over land. This extra energy in the outer portions of Sandy may have enabled it to expand in size later.

4) Interaction with a trough of low pressure over the Bahamas
As Sandy passed through the Bahamas on October 25, the storm encountered strong upper-level winds associated with a trough of low pressure to the west. These winds created high wind shear that helped weaken Sandy and destroy the eyewall. However, Sandy compensated by spreading out its tropical storm-force winds over a much wider area. Between 15 and 21 UTC on October 25, Sandy's area of tropical storm-force winds increased by more than a factor of two.

5) Leveraging of the Earth's spin
As storms move towards Earth's poles, they acquire more spin, since Earth's rotation works to put more vertical spin into the atmosphere the closer one gets to the pole. This extra spin helps storms grow larger, and we commonly see hurricanes grow in size as they move northwards.

6) Interaction with a trough of low pressure at landfall
As Sandy approached landfall in New Jersey, it encountered an extratropical low pressure system to its west. This extratropical storm began pumping cold air aloft into the hurricane, which converted Sandy into an extratropical low pressure system, or "Nor'easter". The nature of extratropical storms is to have a much larger area with strong winds than a hurricane does, since extratropical storms derive their energy from the atmosphere along a frontal boundary that is typically many hundreds of miles long. Thus, as Sandy made landfall, the hurricane's strongest winds spread out over a larger area, causing damage from Indiana to Nova Scotia.

Are we likely to see more such storms in the future?
Global warming theory (Emanuel, 2005) predicts that a 2°C (3.6°F) increase in ocean temperatures should cause an increase in the peak winds of the strongest hurricanes of about about 10%. Furthermore, warmer ocean temperatures are expected to cause hurricanes to dump 20% more rain in their cores by the year 2100, according to computer modeling studies (Knutson et al., 2010). However, there has been no published work describing how hurricane size may change with warmer oceans in a future climate. We've seen an unusual number of Atlantic hurricanes with large size in recent years, but we currently have no theoretical or computer modeling simulations that can explain why this is so, or if we might see more storms like this in the future. However, we've seen significant and unprecedented changes to our atmosphere in recent decades, due to our emissions of heat-trapping gases like carbon dioxide. The laws of physics demand that the atmosphere must respond. Atmospheric circulation patterns that control extreme weather events must change, and we should expect extreme storms to change in character, frequency, and intensity as a result--and not always in the ways our computer models may predict. We have pushed our climate system to a fundamentally new, higher-energy state where more heat and moisture is available to power stronger storms, and we should be concerned about the possibility that Hurricane Sandy's freak size and power were partially due to human-caused climate change.

References
Emanuel, K. (2005). Increasing destructiveness of tropical cyclones over the past 30 years. Nature, 436(7051), 686-688.

Hill, Kevin A., and Gary M. Lackmann (2009), "Influence of environmental humidity on tropical cyclone size," Monthly Weather Review 137.10 (2009): 3294-3315.

Knutson, T. R., McBride, J. L., Chan, J., Emanuel, K., Holland, G., Landsea, C., ... & Sugi, M. (2010). Tropical cyclones and climate change. Nature Geoscience, 3(3), 157-163.

Rotunno, R., & Emanuel, K. A. (1987). An air–sea interaction theory for tropical cyclones. Part II: Evolutionary study using a nonhydrostatic axisymmetric numerical model. J. Atmos. Sci, 44(3), 542-561.

The Atlantic is quiet, but a Nor'easter expected next week
The Atlantic is quiet, with no threat areas to discuss. An area of low pressure is predicted to develop just north of Bermuda on Wednesday, and the GFS model predicts that this low could become a subtropical cyclone as moves north-northeastwards out to sea late in the week.

The long-range models are in increasing agreement that a Nor'easter will develop near the North Carolina coast on Sunday, then move north to northeastwards early next week. High winds, heavy rain, and coastal flooding could affect the mid-Atlantic coast and New England coasts next Monday and Tuesday due to this storm, but it appears likely that the Nor'easter will stay farther out to sea than the last Nor'easter and have less of an impact on the region devastated by Sandy. Ocean temperatures off the coast of North Carolina were cooled by about 4°F (2.2°C) due to the churning action of Hurricane Sandy's winds, but are still warm enough at 22 - 24°C to potentially allow the Nor'easter to acquire some subtropical characteristics. I doubt the storm would be able to become a named subtropical storm, but it could have an unusual amount of heavy rain if it does become partially tropical. The Nor'easter is still a long ways in the future, and there is still a lot of uncertainty on where the storm might go.

Jeff Masters

Hurricane Climate Change

Updated: 22:26 GMT le 13 novembre 2012

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Despite a cool October, U.S. on track for its warmest year on record

By: JeffMasters, 19:06 GMT le 10 novembre 2012

For the first time in sixteen months, the contiguous U.S. has had a month with below-average temperatures, with October 2012 ranking as the 44th coldest (73rd warmest) October since record keeping began in 1895, said NOAA's National Climatic Data Center (NCDC) in their latest State of the Climate report. Temperature extremes were scarce in October, as no states had a top-ten warmest or coldest October. Despite the cool October temperatures, the year-to-date period of January - October was the warmest such period on record for the contiguous U.S.--a remarkable 1.1°F above the previous record. Even if the remainder of 2012 ranks historically in the coldest one-third of November - Decembers ever seen, 2012 will beat out 1998 for warmest year. The first ten days of November have been warmer than average, and the next two weeks are predicted to also average out on the warm side, so it appears likely that we will have to have our coldest December on record in order to keep 2012 from setting the new mark. The November 2011 - October 2012 period was the warmest such 12-month period on record for the contiguous U.S., and the seven warmest 12-month periods since record keeping began in 1895 have all ended during 2012.

Texas had their 9th driest October on record last month, and Washington, Michigan Ohio, Maine, and Maryland had top-ten wettest Octobers; Delaware had their wettest October on record, thanks to rains from Hurricane Sandy. The area of the U.S. experiencing moderate-to-exceptional drought shrank from 65% at the beginning of October to 59% by November 6, with drought conditions improving across parts of the Midwest and Northeast, but worsening across portions of the Northern Rockies.


Figure 1. Year-to-date temperatures for the contiguous U.S. through October, compared to the previous record warmest years in U.S. history. The year-to-date period (thick black line) is 1.1°F warmer than the previous record, set in 1998. Even if the remainder of 2012 ranks historically in the coldest one-third of November - Decembers on record (dark blue line), 2012 will beat out 1998 for the warmest year on record. The data for 2012 are preliminary. Image credit: NOAA/NCDC.

Second most extreme January - October period on record
The year-to-date period was the second most extreme on record in the U.S., according to NOAA's U.S. Climate Extremes Index (CEI), which tracks the percentage area of the contiguous U.S. experiencing top-10% and bottom-10% extremes in temperature, precipitation, and drought. The CEI was 38% during the year-to-date January - October period. This was exceeded only in 1998 (41%), and was nearly double the average value of 20%. Remarkably, 85% of the contiguous U.S. had maximum temperatures that were in the warmest 10% historically during the first ten months of 2012, and 76% of the U.S. of the U.S. had warm minimum temperatures in the top 10%. Both are records. The percentage area of the U.S. experiencing top-10% drought conditions was 28%, which was the 7th greatest since 1910. Only droughts in 2002, 1954 - 1956, and during the Dust Bowl years of 1931 and 1934 were more extreme for the January - October period. Heavy 1-day downpours were below average, though, with 8% of nation experiencing top-10% extremes in October 2012, compared to an average of 10%.


Figure 2. NOAA's U.S. Climate Extremes Index (CEI) for January - October shows that 2012 had the second most extreme first ten months of the year on record, with 38% of the contiguous U.S. experiencing top-10% extreme weather.

The Atlantic is quiet
An area of disturbed weather about 1100 miles west of the Cape Verde Islands has been torn apart by wind shear of 30 - 50 knots. In their 1 pm EST Tropical Weather Outlook, NHC gave the disturbance a 0% chance of developing into a tropical cyclone by Monday. An area of low pressure is predicted to develop just north of Bermuda on Wednesday, and the GFS model predicts that this low could become a subtropical cyclone as moves north-northeastward out to sea late in the week.

Have a great weekend, and I'll be back on Monday with a new post.

Jeff Masters

Climate Summaries

Updated: 14:17 GMT le 11 novembre 2012

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Sandy the 11th U.S. billion-dollar disaster of 2012

By: JeffMasters, 16:26 GMT le 09 novembre 2012

Devastating Hurricane Sandy was the eleventh billion-dollar weather-related disaster in the U.S. so far this year, and the most expensive, said insurance broker AON Benfield in their November 8, 2012 Catastrophe Report. This puts 2012 in second place for most U.S. billion-dollar weather disasters behind 2011, when NOAA's National Climatic Data Center (NCDC) counted fourteen such disasters. AON Benfield rated seventeen events as billion-dollar weather disasters in 2011, so the actual number of such disasters has considerable uncertainty depending upon who is doing the estimates. NCDC has not yet released their official figures for 2012's billion-dollar weather disasters, and we might expect that their total could be 20% lower than AON Benfield's, judging by what happened in 2011. This would give 2012 nine billion-dollar weather disasters, which would still put 2011 in second place for most billion-dollar weather disasters. Although damages due to weather-related disasters are increasing, we cannot yet say climate change is to partially to blame. There are too many other complicating factors such as increases in wealth and population that may be responsible for the rise in damages, and there is too much noise in the data to see the signal of climate change, as I explain in my January 2012 post, "Damage losses and climate change". We are better off looking at the atmosphere itself to find evidence of climate change, and there are plenty of examples of that--such as the record loss of Arctic sea ice this summer.


Figure 1. The escalators down to the South Ferry subway station in Lower Manhattan's Financial District lie flooded in the wake of Hurricane Sandy's storm surge on October 29, 2012. Total economic damage from Hurricane Sandy has been estimated at $30 - $50 billion by EQECAT. Image credit: New York MTA and Associated Press.


Figure 2. The U.S. has experienced eleven weather-related disasters costing at least $1 billion in 2012, according to data taken from the AON Benfield October 2012 Catastrophe Report. AON Benfield has not made a damage estimate for the 2012 Midwest drought, but according to National Crop Insurance Services, crop insurance losses alone will total $20 billion. The total cost of the drought could be more than $77 billion, said Purdue University economist Chris Hurt in August. As Nick Sundt of the WWF summarizes in a nice blog post, this year will probably be the second most costly year since 1980 in terms of billion-dollar weather-related disasters.


Figure 3. Number of weather-related U.S. billion-dollar disasters per year (blue bars) from 1980 - 2012, and the total cost of these disasters (red and dark blue lines, with the red line showing the inflation-adjusted costs.) Image credit: NOAA's National Climatic Data Center (NCDC)

Winter Storm Brutus bringing blizzard conditions to Montana
Winter Storm Brutus is bringing blizzard conditions to Northeast Montana, with heavy snow and high winds that have gusted to 45 mph. Brutus has dumped a widespread area of 4 - 6 inches of snow over large portions of Montana since Thursday afternoon, with 7 - 10 inches reported in the Great Falls area and 17" in the mountains near Glacier National Park. According to the Glasgow, MT NWS Facebook page, the current storm has the potential to be a top-ten snowfall event for the area, with records going back 115 years. The storm will affect Montana and western North Dakota through Saturday morning, then push north-northeastwards into Canada.

Top ten 2-day snow events in Glasgow, Montana history:

1 15.0" 4/18/1896
2 14.3" 12/27/2003
3 14.1" 4/ 3/1940, 4/ 2/1940
5 14.0" 11/19/1941
6 13.4" 10/13/2008
7 13.3" 11/ 6/2000
8 13.0" 10/12/2008, 4/ 9/1995, 1/26/1916

The Atlantic hurricane season is not over yet
There are still three weeks left in the Atlantic hurricane season, and the way this year has gone, I wouldn't be surprised to see the season's 20th named storm--Tropical Storm Valerie--sometime this month. One potential candidate is a concentrated area of heavy thunderstorms that has developed about 800 miles west-northwest of the Cape Verde Islands, off the coast of Africa. However, wind shear is a high 20 - 30 knots over the disturbance, and any development should be slow. Our two most reliable models, the GFS and ECMWF, do not develop the disturbance, and show it drifting slowly to the northwest over the next few days. In their 7 am EST Tropical Weather Outlook, NHC gave the disturbance just a 20% chance of developing into a tropical cyclone by Sunday morning.

A better candidate to become Valerie is an area of low pressure that is predicted to develop between Bermuda and Puerto Rico by the middle of next week. The GFS model shows this low becoming a subtropical cyclone as it gets pulled to the north or north-northeast late next week.

Jeff Masters

Extreme Weather Brutus

Updated: 22:27 GMT le 13 novembre 2012

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Winter Storm Athena batters the Northeast; Brutus takes aim at Montana

By: JeffMasters, 15:28 GMT le 08 novembre 2012

“I am waiting for the locusts and pestilence next,” said New Jersey Governor Chris Christie at a press conference on Wednesday, after Winter Storm Athena punished New Jersey with heavy snows, high winds, and a 3-foot storm surge. The storm brought unexpectedly high snowfall amounts along a swath from Central New Jersey northeastwards across Southeast New York, Long Island, Connecticut, and South Central Massachusetts. The 4.7" of snow that fell at New York City's Central Park was the city's earliest 4-inch snowfall on record. The old record for earliest 4-inch snow was Nov. 23 in 1989. Last year's Snowtober storm brought the earliest 2" snowfall on record in NYC on October 29, 2011, but the city didn't surpass the 4.7" mark until January 21, as winter basically failed to show up. The 5.7" of snow that fell in Newark, NJ Wednesday was the heaviest single-day November snowfall on record in Newark (going back to 1931), and the earliest snowfall of that magnitude on record (the previous record was set just last year, when the Snowtober storm dumped 5.2" of snow on October 29, 2011.) Several locations in New Jersey and Connecticut recorded a foot a more of snow during Athena, with the storm's highest total of 13.5" recorded in Clintonville, CT. High winds combined with the heavy snows and rains to knock out power to 375,000 additional customers in New York, New Jersey, and Connecticut yesterday, and a storm surge of 2 - 3.5' hit most of the mid-Atlantic and New England coasts, from Virginia to Massachusetts. The storm brought waves of 20' to the waters offshore of Long Island, NY and near Block Island, RI. The top winds over water were 61 mph, gusting to 76 mph, in Buzzard's Bay, MA. Here are the top wind gusts from Athena as of 8 am EST on Thursday, November 8, 2012:




Figure 1. A resident clears out destroyed household belongings from his flood-damaged home as snow falls on November 7, 2012 in the Staten Island borough of New York City. How often do you see snow falling on hurricane-damaged coasts? This sort of one-two weather punch is unprecedented in my lifetime. Image credit: AP.

The good news for the Northeast is that locusts and pestilence are not next, but rather sunny skies and a substantial warm-up. Athena, currently centered just south of Cape Cod, Massachusetts, will move off to the northeast today, leaving sunny skies in its wake. Highs will be near 50°F today in New York City, and will warm to mid-60s by this weekend.

Here comes Brutus: major blizzard coming for Montana
Right on the heels of Winter Storm Athena comes Winter Storm Brutus--a powerful low pressure system that is taking shape over Southern Montana this morning. Light snows have begun in Southwest Montana, and will spread to the northwest across much of Montana and into western North Dakota this afternoon through Saturday. As much as 12” to 18” of snowfall is expected for several major cities in Montana, including Great Falls, and over 2 feet is expected in the mountains.  According to the Glasgow, MT NWS Facebook page, the current storm total snowfall amounts north of the Missouri River/Fort Peck areas would be within the top 10 two day snowfall totals across this region, going back 115 years. Strong winds will combine with heavy snowfall to produce blizzard conditions across northeast Montana. Brutus is forming in response to an usually large loop in the jet stream over the Western U.S. On the east side of the jet stream axis, a southwesterly flow of air has pumped in record-breaking warm air from the Desert Southwest. Sheridan, Wyoming hit 79°F Wednesday, breaking their previous all-time monthly record of 78° set on Nov. 5, 1975. Records go back to 1893. However, Sheridan will be on the west side of jet stream by Saturday, as the cold front associated with Brutus passes through Wyoming. This will bring Sheridan powerful northwest winds, 4 - 8 inches of snow, and high temperatures 50° colder than Wednesday's.

Jeff Masters

Winter Weather Brutus

Updated: 12:06 GMT le 10 novembre 2012

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First Hurricane Sandy, now Winter Storm Athena for the Eastern U.S.

By: JeffMasters, 14:57 GMT le 07 novembre 2012

Winter Storm Warnings are up for Southwest New Jersey, Northern Delaware, and Southeast Pennsylvania, including Philadelphia, PA, where Winter Storm Athena is expected to drop 3 - 5" of snow today through Thursday morning. Slushy accumulations of up to 1" are likely in Baltimore, and non-accumulating snow will fall as far south as Washington, DC. Athena, the season's first Nor'easter and first winter storm to get a name under The Weather Channel's new naming system, is spreading rain and high winds into Southern New Jersey and Eastern Long Island, NY this morning. Winds at buoy 44025, about 40 miles offshore from the coast of Central New Jersey, reached 40 mph, gusting to 49 mph, with a significant wave height of 14', at noon EST. Winds at Nantucket, MA have gusted as high as 54 mph this morning. Athena is building a storm surge that has already reached 2.2' at Atlantic City and 1.8' at New York City as of noon EST. A storm surge of 2 - 3.5' is likely along the section of coast most heavily damaged by Sandy's storm surge, and battering waves up to 20' high will cause moderate beach erosion along much of the New Jersey and New York shoreline. The storm surge will cause minor to moderate flooding during this afternoon's high tide cycle near 1 pm EST, and again at the next high tide, near 1 am EST Thursday morning. Fortunately, the high tides this week will be some of the lowest of the month, since we are midway between the new moon and full moon. Wind gusts from Athena will likely reach 50 mph along the coasts of New Jersey and Southern Long Island, NY, and could hit 60 mph on Cape Cod, Massachusetts. I expect that Athena's winds, rains, and wet, heavy snows will cause up to 50,000 new power outages today. As of early Wednesday morning, 676,000 customers were still without power in the wake of Hurricane Sandy (down from a peak of 8.5 million customers.)


Figure 1. Winter Storm Athena as seen at 9:01 am EST November 7, 2012. Image credit: NOAA/GSFC.


Figure 2. Predicted storm surge at Sandy Hook, NJ, for Winter Storm Athena, from the experimental Extratropical Storm Surge model, run by NOAA's Meteorological Development Laboratory. This model used winds from this morning's 6Z (1 am EDT) run of the GFS model. The peak storm surge (yellowish-brown line) is predicted to be 3.4', occurring Wednesday evening. High tide (green line) occurs near 1 pm Wednesday afternoon, resulting in a peak storm tide of approximately 7.2' around 1 pm Wednesday (black line). For comparison, Sandy delivered a 8.6' storm surge to Sandy Hook before their tide gauge failed, with the storm tide reaching 13.2' above MLLW (Mean Lower Low Water.)

The decision to name Athena
The Weather Channel announced in October that they would begin naming winter storms this year, in an effort to aid in raising awareness and reduce the risks the public faces. One of the main criteria for naming a storm is its impact on populated areas; the meteorology of the storm may not get it named, if the storm doesn't affect a populated area. If Hurricane Sandy had not devastated the region of coast being affected by today's Winter Storm Athena, it may not have gotten a name. With so many people still under recovery efforts even well inland, the combination of heavy, wet snow and wind prompted the decision to name Athena. The models have been trending towards more cold air getting pulled into this system, so it is possible Athena could drop heavier snows than currently advertised. The National Weather Service will not be referring to today's Nor'easter as "Athena". They put out this internal directive: "The NWS does not use named winter storms in our products. Please refrain from using the term Athena in any of our products."

Here are the peak wind gusts from Athena as of 11 am EST on Wednesday, November 7, 2012:



Jeff Masters

Winter Weather Athena

Updated: 17:08 GMT le 07 novembre 2012

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Wednesday's Nor'easter to have lower impact than originally feared

By: JeffMasters, 16:11 GMT le 06 novembre 2012

An early-season Nor'easter is taking shape along the coast of South Carolina today, but is now forecast to be weaker and move farther offshore than originally forecast, resulting in lower impacts to the New Jersey and New York coasts than originally feared. The storm will head north-northeast along the coast on Wednesday, intensifying into a 990 mb Nor'easter, a few hundred miles south of Long Island, NY, by Wednesday evening. The storm will likely bring wind gusts up to 50 mph and a storm surge of 2 - 3 feet along the coasts of Virginia, Maryland, New Jersey, and New York, including New York City. High waves of 10 - 20 feet will ride on top of this surge, and cause moderate beach erosion along much of the coastline damaged by Hurricane Sandy. The greatest flooding will occur during the Wednesday early afternoon high tide cycle, near 1 pm EST. Fortunately, the high tides this week will be some of the lowest of the month, since we are midway between the new moon and full moon. The Nor'easter's strongest winds will likely affect eastern Long Island and coastal Massachusetts, where wind gusts up to 60 mph will be possible Wednesday evening and Thursday. The storm's heaviest rains will stay offshore, and only Eastern Massachusetts can expect to see more than 1" of rain. The storm isn't going to tap into a large reservoir of cold, Arctic air, which will limit snowfall amounts to perhaps 1 - 2" along a swath from Northern New Jersey northeastwards, across Western Massachusetts and into Maine. While the storm will slow down recovery efforts from Hurricane Sandy, this is a pretty ordinary Nor'easter of the type the Northeast sees several times per year, and will not cause major damage.


Figure 1. Predicted wind speed for 1 pm EST Wednesday, November 7, 2012, from the 12Z (7 am EST) run of the GFS model made on Tuesday, November 6, 2012. Winds tropical storm-force (39+ mph) are predicted to affect Southern New Jersey, eastern Long Island, Rhode Island, and Massachusetts, but miss the areas hardest hit by Sandy--northern New Jersey and the New York City area.


Figure 2. Predicted storm surge at Sandy Hook, NJ for Wednesday's Nor'easter, from the experimental Extratropical Storm Surge model, run by NOAA"s Meteorological Development Laboratory. This model used winds from this morning's 6Z (1 am EDT) run of the GFS model. The peak storm surge (yellowish-brown line) is predicted to be 3.7', occurring Wednesday afternoon. High tide (green line) occurs near 1 pm Wednesday afternoon, resulting in a peak storm tide of approximately 7.8' around 1 pm Wednesday (black line). For comparison, Sandy delivered a 8.6' storm surge to Sandy Hook before their tide gauge failed, with the storm tide reaching 13.2' above MLLW (Mean Lower Low Water.)

More Sandy links
I gave a TED talk in Bermuda in October 2011, and presented a list of nine potential $100 billion weather disasters that could happen in the next 30 years. Number six on my list was a hurricane hitting New York City. “We really don’t know what climate change is going to do to hurricanes,” I said, “but it makes sense that it’ll probably make the strongest ones stronger.” If you want to see what I had to say about a hurricane hitting New York City, plus the other eight disasters I think have at least a 10% chance of happening in the next 30 years, the 18-minute video is up on the main TED site. (I've since updated my list to twelve potential $100 billion disasters, and plan on running a blog series on the topic in 2013.)

Was Sandy a hurricane at landfall? Lee Grenci, a senior lecturer and forecaster at the Department of Meteorology at Penn State, weighs in on the matter in this guest blog post. He presents evidence that Sandy was not a hurricane at landfall, and was instead a rapidly evolving hybrid storm. Lee , who is a frequent contributor to Weatherwise magazine, will be joining wunderground as a featured blogger in December, and we're looking forward to having his excellent writings!

Be sure to vote today!

Jeff Masters

Winter Weather

Updated: 17:38 GMT le 06 novembre 2012

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Nor'easter coming Wednesday and Thursday

By: JeffMasters, 15:26 GMT le 05 novembre 2012

An early-season Nor'easter will form off the coast of South Carolina on Tuesday evening. Once over the warm waters off the coast, the low will intensify, spreading heavy rains of 1 - 2" over coastal North Carolina on Tuesday night and Wednesday morning. The storm will accelerate to the north-northeast on Wednesday and pull in cold air from Canada, and intensify into a medium-strength Nor'easter with a central pressure near 984 mb by Wednesday evening. While the exact track of the storm still has considerable uncertainty, the models are pretty unified on the timing and strength of this storm. A 12-hour period of strong winds of 40 - 45 mph will likely affect portions of the coast from Maryland to Massachusetts. A more westerly track, as currently predicted by our top model, the European ECMWF model, would likely result in the storm's strongest winds affecting the New Jersey coast. A storm surge of 2 - 4 feet would likely hit the New Jersey coast, and a storm surge of 3 - 5 feet would likely impact the western end of Long Island Sound. These surges would be accompanied by high, battering waves, capable of causing moderate to locally severe erosion along the coastal areas pounded by Hurricane Sandy last week. Fortunately, the high tides this week will be some of the lowest of the month, since we are midway between when the new moon and full moon occur. A more easterly track for the storm, as predicted by the GFS model, would put the Nor'easter's strongest winds along eastern Long Island and coastal Massachusetts, resulting in lower storm surges for New Jersey and New York City. Accompanying the storm will be a swath of 2 - 3" of rain, with the heaviest rains falling over Eastern Massachusetts and Rhode Island. The storm isn't going to tap into a large reservoir of cold, Arctic air, which will limit its intensity and snowfall amounts. Snow is not expected in coastal area, but the Nor'easter has the potential to bring more than a foot of snow to mountain areas of New England.


Figure 1. Predicted wind speed for Wednesday evening, November 7, 2012, from the ECMWF model (left) and GFS model (right). The ECMWF model was run using data from 00Z (7 pm EST) Sunday night, and the GFS model was run using data beginning at 06Z (1 am EST) on Monday. Winds tropical storm-force (39+ mph) are predicted to extend from coastal Virginia to Massachusetts.


Figure 2. Predicted storm surge at Atlantic City, NJ for Wednesday's Nor'easter, from the experimental Extratropical Storm Surge model, run by NOAA"s Meteorological Development Laboratory. This model used winds from this morning's 6Z (1 am EDT) run of the GFS model. The peak storm surge (yellowish-brown line) is predicted to be 3.3', occurring just after midnight local time on Wednesday night. High tide (green line) occurs near 1 am Thursday morning, resulting in a peak storm tide of approximately 7.4' around 1 am Thursday (black line). For comparison, Sandy delivered a 5.81' storm surge to Atlantic City, with the highest storm tide reaching 8.9' above MLLW.

Jeff Masters

Winter Weather

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A moderate-strength Nor'easter on Wednesday looking increasingly likely

By: JeffMasters, 19:38 GMT le 03 novembre 2012

Storm-weary U.S. residents pounded by Superstorm Sandy may have a new storm to contend with on Wednesday: an early-season Nor'easter is expected to impact the mid-Atlantic and New England with strong winds and heavy rain. Our two top models, the European (ECMWF) and GFS (run by the U.S. National Weather Service), are now in agreement on both the track and intensity of the storm. The storm will move off the coast of South Carolina/Georgia on Tuesday evening. Once over the warm waters off the coast, the low will intensify, spreading heavy rains of 2 - 3" over coastal North Carolina on Tuesday night and Wednesday morning. The storm will accelerate to the north-northeast on Wednesday and pull in cold air from Canada, intensifying into a medium-strength Nor'easter with a central pressure of 984 mb by Wednesday evening. The European model, which did an exemplary job forecasting Hurricane Sandy, is slower, predicting the Nor'easter's highest winds will begin affecting New Jersey on Wednesday night. The GFS model is about 12 hours faster, predicting the strongest winds will arrive on Wednesday morning. A 12-hour period of strong winds of 40 - 45 mph will likely affect the coast from Maryland to Massachusetts, accompanied by a swath of 2 - 3" of rain. The heaviest rains will likely fall over Eastern Massachusetts and Rhode Island. The storm also has the potential to bring more than a foot of snow to mountain areas of New England. The storm is still four days away, and four-day forecasts of the path and intensity of Nor'easters usually have large errors. Nevertheless, residents and relief workers in the region hit by Sandy should anticipate the possibility of the arrival on Wednesday of a moderate-strength Nor'easter with heavy rain, accompanied by high winds capable of driving a 1 - 2 foot storm surge with battering waves. The surge and waves will potentially cause moderate to severe erosion on New Jersey coast, where Hurricane Sandy pulverized the protective beach dunes.


Figure 1. Predicted wind speed for Thursday morning, November 8, 2012, from the ECMWF model (left) and predicted wind speed for 2 pm EST on Wednesday, November 7, from the GFS model (right). Both models runs were done beginning at 12Z (8 am EDT) on November 3, 2012. Winds tropical storm-force (39+ mph) are predicted to extend from coastal Virginia to Massachusetts. The GFS model brings the Nor'easter to a point off the New Jersey coast about 12 hours faster than the ECMWF model.


Figure 2. Forecast track error for four of our top models used to predict Hurricane Sandy. The GFS model performed the best for 1 - 3 day forecasts, but the European (ECMWF) model far out-performed all models at longer-range 4 - 5 day forecasts. This may be due to the fact the model was able to successfully predict the timing of the arrival of a trough of low pressure over the Eastern U.S. that acted to steer Sandy to the north and then northwest. Image credit: Morris Bender, NOAA/GFDL.

Charities mobilize for Sandy
Sandy's death toll of 109 in the U.S. makes it the 25th deadliest hurricane in U.S. history, and the 2nd deadliest since 1972, when Hurricane Agnes killed 122 in the Northeast U.S. The main owners of The Weather Channel have agreed to match donations of up to $1 million to the American Red Cross, with all donations to benefit people in the hard-hit areas of the U.S. To have your donation matched, please visit www.redcross.org/sandy, or text SANDY to 90999. I also recommend my favorite disaster relief charity, Portlight.org. They are focusing their response efforts exclusively on the post-Sandy needs of people with disabilities.Check out the Portlight blog to see what they're up to. Sandy's greatest devastation occurred in Haiti, where rains of up to 20 inches in 24 hours unleashed rampaging flood waters that killed at least 54, left 200,000 homeless, wiped out thousand of acres of crops, and killed massive numbers of livestock. For impoverished families in Haiti still struggling to recover from the earthquake in 2010 and Hurricane Isaac in August, Sandy was devastating. These crops are the very essence of rural Haitian’s livelihoods, and there are fears widespread starvation will result. A disaster relief charity in Haiti that I've contributed to for many years, The Lambi Fund of Haiti, is seeking donations to help farmers purchase local seeds so that they can replant their crops in the wake of this latest terrible Haitian catastrophe.

I'll have an update Monday, unless there's some major change in the model forecasts for the coming Nor'easter.

Jeff Masters

Hurricane

Updated: 19:40 GMT le 03 novembre 2012

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Moderate-strength Nor'easter may hit Sandy-devastated areas Wednesday

By: JeffMasters, 16:16 GMT le 02 novembre 2012

Storm-weary U.S. residents pounded by Superstorm Sandy may have a new storm to contend with next Wednesday: an early-season Nor'easter is expected to impact the mid-Atlantic and New England with strong winds and heavy rain. Our two top models, the European (ECMWF) and GFS (run by the National Weather Service), both predict that an area of low pressure will move off the coast of South Carolina on Tuesday evening. Once over the warm waters off the coast, the low will intensify, spreading heavy rains over coastal North Carolina on Tuesday night and Wednesday morning. The storm will accelerate to the north-northeast on Wednesday and pull in cold air from Canada. The storm is predicted to intensify into a medium-strength Nor'easter with a central pressure of 992 mb by Wednesday afternoon, when it will be centered a few hundred miles south of Long Island, NY. The European model, which did an exemplary job forecasting Hurricane Sandy, predicts a stronger storm that will stay just offshore and bring a 12-hour period of strong winds of 40 - 45 mph to the coasts of Maryland, Delaware, New Jersey, and New York on Wednesday morning and afternoon. The GFS model and 06Z NOGAPS model runs from 06Z (2 am EDT) this morning have a weaker storm that is farther offshore, with the main impact of the Nor'easter occurring Wednesday evening in coastal Massachusetts, Rhode Island, and Maine. The Nor'easter will likely bring a swath of 2 - 4" of rain to the coast, and the potential for more than a foot of snow to mountain areas of the New England. The storm is still five days away, and five-day forecasts of the path and intensity of Nor'easters usually have large errors. Nevertheless, residents and relief workers in the region hit by Sandy should anticipate the possibility of the arrival on Wednesday of a moderate-strength Nor'easter with heavy rain, accompanied by high winds capable of driving a 1 - 2 foot storm surge with battering waves.


Figure 1. Predicted wind speed for Wednesday morning, November 7, 2012, from the 00Z (8 pm EDT) run of the ECMWF model made on November 2, 2012. Winds tropical storm-force (40 - 45 mph) are predicted to extend from coastal Maryland to the east tip of Long Island, NY.


Figure 2. Forecast track error for four of our top models used to predict Hurricane Sandy. The GFS model performed the best for 1 - 3 day forecasts, but the European (ECMWF) model far out-performed all models at longer-range 4 - 5 day forecasts. This may be due to the fact the model was able to successfully predict the timing of the arrival of a trough of low pressure over the Eastern U.S. that acted to steer Sandy to the north and then northwest. Image credit: Morris Bender, NOAA/GFDL.


Figure 3. Forecast track error for four of our top models used to predict Hurricane Sandy, for their runs that began at 00Z October 25, 2012. The GFDL and ECMWF models made great forecasts that correctly showed Sandy making landfall in Southern New Jersey in five days. The GFS and HWRF models made good 1 - 3 day forecasts, but failed to anticipate Sandy's northward turn towards the U.S. coast. Image credit: Morris Bender, NOAA/GFDL.

Links
Impressive loop of 1-minute visible satellite imagery spanning 6 days of Sandy's life.

A one-day time lapse video from a New York City webcam showing Sandy's impact on the city. It's eerie to see the city suddenly plunged into darkness.

First round of damage assessment aerial imagery collected by NOAA's National Geodetic Survey on Oct. 31 along the New Jersey coast.


Figure 4. Flooding in Haiti from Hurricane Sandy. Image credit: The Lambi Fund of Haiti.

Charities mobilize for Sandy
Sandy's death toll of 98 in the U.S. makes the storm one of the 30 most deadly hurricanes to affect the U.S.. The outpouring of charitable donations in the wake of the terrible storm has been great to see. NBC is hosting a benefit concert at 8 pm tonight (Friday), and the main owners of The Weather Channel have agreed to match donations of up to $1 million to the American Red Cross, with all donations to benefit people in the hard-hit areas of the U.S. To have your donation matched, please visit www.redcross.org/sandy, or text SANDY to 90999. I also recommend my favorite disaster relief charity, Portlight.org. They are focusing their response efforts exclusively on the post-Sandy needs of people with disabilities.Check out the Portlight blog to see what they're up to.

Sandy's greatest devastation occurred in Haiti, where rains of up to 20 inches in 24 hours unleashed rampaging flood waters that killed at least 54, left 200,000 homeless, wiped out thousand of acres of crops, and killed massive numbers of livestock. For impoverished families in Haiti still struggling to recover from the earthquake in 2010 and Hurricane Isaac in August, Sandy was devastating. These crops are the very essence of rural Haitian’s livelihoods, and there are fears widespread starvation will result. A disaster relief charity in Haiti that I've contributed to for many years, The Lambi Fund of Haiti, is seeking donations to help farmers purchase local seeds so that they can replant their crops in the wake of this latest terrible Haitian catastrophe.

I'll have an update this weekend on the coming Nor'easter.

Jeff Masters

Hurricane Winter Weather

Updated: 19:39 GMT le 02 novembre 2012

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Sandy by the numbers: trying to comprehend a stunning disaster

By: JeffMasters, 19:19 GMT le 01 novembre 2012

The immensity of the impact of Superstorm Sandy on the Eastern U.S. is difficult to comprehend, and the scenes of devastation coming from the impact zone are stunning and heart-wrenching. To help understand the extraordinary scale of this historic storm, I've put together a list of notable statistics from Sandy:

Death toll: 160 (88 in the U.S., 54 in Haiti, 11 in Cuba)

Damage estimates: $10 - $55 billion

Power outages: 8.5 million U.S. customers, 2nd most for a natural disaster behind the 1993 blizzard (10 million)

Maximum U.S. sustained winds: 69 mph at Westerly, RI

Peak U.S. wind gusts: 90 mph at Islip, NY and Tompkinsville, NJ

Maximum U.S. storm surge: 9.45', Bergen Point, NJ 9:24 pm EDT October 29, 2012

Maximum U.S. Storm Tide: 14.60', Bergen Point, NJ, 9:24 pm EDT October 29, 2012

Maximum significant wave height: 33.1' at the buoy east of Cape Hatteras, NC (2nd highest: 32.5' at the Entrance to New York Harbor)

Maximum U.S. rainfall: 12.55", Easton, MD

Maximum snowfall: 36", Richwood, WV

Minimum pressure: 945.5 mb, Atlantic City, NJ at 7:24 pm EST, October 29, 2012. This is the lowest pressure measured in the U.S., at any location north of Cape Hatteras, NC (previous record: 946 mb in the 1938 hurricane on Long Island, NY)

Destructive potential of storm surge: 5.8 on a scale of 0 to 6, highest of any hurricane observed since 1969. Previous record: 5.6 on a scale of 0 to 6, set during Hurricane Isabel of 2003.

Diameter of tropical storm-force winds at landfall: 945 miles

Diameter of ocean with 12' seas at landfall: 1500 miles


Figure 1. The Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi NPP satellite acquired this image of Superstorm Sandy around 3:35 a.m. Eastern Daylight Time (7:35 Universal Time) on October 30. This image is from the “day-night band” on VIIRS, which detects light wavelengths from green to near-infrared. The full Moon lit up the tops of the clouds. Image credit: NASA.



Figure 2. Preliminary death and damage statistics for Sandy as compiled by Wikipedia on November 1, 2012.



Figure 3. Precipitation from Superstorm Sandy for the 7-day period ending at 8 am EDT Thursday, November 1, 2012. Image credit: NOAA/NWS/AHPS.



Figure 4. Top five weather-related power outages in the U.S.



Figure 5. Strong winds from Sandy blow snow in West Virginia on October 30, 2012. Image credit: Beau Dodson


Sandy's snows
Several cities set records for snowiest October day on record during Sandy: Elkin, WV (7", previous record, 4.6" in 1917) and Bluefield (4.7", previous record 3.2" in 1993.) Heavy snows caused roof collapses in West Virginia, and snows of two feet or more fell in four states--West Virginia, Tennessee, Maryland, and Virginia. However, Sandy fell short of setting the all-time record for snowfall from a hurricane. The Vermont Journal estimated that the Snow Hurricane of 1804 dumped up to 4 feet of snow in Vermont.

36" Richwood, WV
34" Mount Leconte, TN
34" Sevier, TN
33" Clayton, WV
32" Snowshoe, WV
29" Quinwood, WV
28" Frostburg, WV
28" Davis, WV
28" Huttonsville, WV
28" Flat Top, WV
26" Redhouse, MD
26" Garret, MD
26" Craigsville, WV
24" Oakland, MD
24" Alpine Lake, WV
24" Nettie, WV
24" Norton, VA
24" Quinwood, WV
24" Alexander, WV

Links
Impressive loop of 1-minute visible satellite imagery spanning 6 days of Sandy's life.

A one-day time lapse video from a New York City webcam showing Sandy's impact on the city. It's eerie to see the city suddenly plunged into darkness.

First round of damage assessment aerial imagery collected by NOAA's National Geodetic Survey on Oct. 31 along the New Jersey coast.


Figure 6. Flooding in Haiti from Hurricane Sandy. Image credit: The Lambi Fund of Haiti.

Charities mobilize for Sandy
The outpouring of charitable donations in the wake of the devastation wrought by Hurricane Sandy has been one of the bright spots in the gloomy aftermath of the storm. The main owners of The Weather Channel have agreed to match donations of up to $1 million to the American Red Cross, if you text SANDY to 90999 ($10). I also recommend my favorite disaster relief charity, Portlight.org. They are focusing their response efforts exclusively on the post-Sandy neeeds of people with disabilities.Check out the Portlight blog to see what they're up to; donations are always needed.

Sandy's greatest devastation occurred in Haiti, where rains of up to 20 inches in 24 hours unleashed rampaging flood waters that killed at least 54, left 200,000 homeless, wiped out thousand of acres of crops, and killed massive numbers of livestock. For impoverished families in Haiti still struggling to recover from the earthquake in 2010 and Hurricane Isaac in August, Sandy was devastating.  These crops are the very essence of rural Haitian’s livelihoods, and there are fears widespread starvation will result. A disaster relief charity in Haiti that I've contributed to for many years, The Lambi Fund of Haiti, is seeking donations to help farmers purchase local seeds so that they can replant their crops in the wake of this latest terrible Haitian catastrophe.

Jeff Masters

Hurricane

Updated: 01:21 GMT le 03 novembre 2012

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About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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