Hurricane Irene: New York City dodges a potential storm surge mega-disaster

By: Dr. Jeff Masters , 16:14 GMT le 30 novembre 2011

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On August 24, 2011, I had good reason to fear New York City's worst-case storm surge disaster might be named Irene. As Category 3 Hurricane Irene ripped through the Bahamas on its way to North Carolina and New England, our most reliable hurricane forecasting model--the European (ECMWF) model--predicted that Irene would intensify to Category 4 strength with a 912 mb central pressure as it grazed the Outer Banks of North Carolina, then slowly weaken to a Category 3 hurricane before hitting southern New Jersey. Just a small perturbation from this scenario would bring Irene over New York City as a Category 2 hurricane. Since Irene was an exceptionally large storm with winds that covered a huge stretch of ocean, the storm had a much larger storm surge than it peak winds would suggest, and could have easily brought a storm surge of 15 - 20 feet to New York City. The storm would arrive during the new moon, when tides were at their highest levels of the month, compounding the storm surge risk.

Thankfully, the ECMWF model was wrong, and Irene's eyewall collapsed before the hurricane reached North Carolina. Irene made a direct hit on New York City as a tropical storm with 65 mph winds. Irene's storm surge reached 4.3 feet at the Battery on the south shore of Manhattan, which was high enough to top the city's seawall and flood low-lying park lands and roads near the shore. Fortunately, the water was not high enough to flood New York City's subway system, which could have easily occurred had Irene's winds been just 5 - 10 mph stronger.


Figure 1. Wind forecast for August 28, 2011 made on August 24, 2011 by the ECMWF model for Hurricane Irene. The model predicted that Irene would be a Category 3 or 4 hurricane with a 936 mb central pressure four days later, just south of New Jersey.

New York City: my number one storm surge disaster concern
I met last year with the head of the National hurricane Center's storm surge unit, Jaime Rhome, and asked him what his number one concern was for a future storm surge disaster. Without hesitation, he replied, "New York City." I agreed with him. Strong hurricanes don't make it to New York City very often, since storms must hit the city from the south or southeast in order to stay over water, and most hurricanes are moving northeast or north-northeast when they strike New England. New York also lies far to the north, where cold water and wind shear can tear up any hurricane that might approach. But if you throw the weather dice enough times, your number will eventually come up. New York City's number came up on September 3, 1821, when what was probably a Category 2 hurricane with 110 mph winds struck the city. The water rose 13 feet in just one hour at the Battery, and flooded lower Manhattan as far north as Canal Street--an area that now houses the nation's financial center. The maximum storm surge from this greatest New York City hurricane is unknown, but could have been 15 - 20 feet, which is what NOAA's SLOSH model predicts could occur for a mid-strength Category 2 hurricane with 100-mph winds.


Figure 2. The height above ground that a mid-strength Category 2 hurricane with 100 mph winds would would create in New York City in a worst-case scenario. The image was generated using the primary computer model used by the National Hurricane Center (NHC) to forecast storm surge--the Sea, Lake, and Overland Surge from Hurricanes (SLOSH) model. The accuracy of the SLOSH model is advertised as plus or minus 20%. This "Maximum Water Depth" image shows the water depth at each grid cell of the SLOSH domain. Thus, if you are inland at an elevation of ten feet above mean sea level, and the combined storm surge and tide (the "storm tide") is fifteen feet at your location, the water depth image will show five feet of inundation. This Maximum of the "Maximum Envelope of Waters" (MOM) image was generated for high tide and is a composite of the maximum storm surge found for dozens of individual runs of different Category 2 storms with different tracks. Thus, no single storm will be able to cause the level of flooding depicted in this SLOSH storm surge image. Consult our Storm Surge Inundation Maps for the U.S. coast for more imagery.

New York City's storm surge history
During the December 12, 1992 Nor'easter, powerful winds from the 990 mb storm drove an 8.5-foot storm surge into the Battery Park on the south end of Manhattan. The ocean poured over the city's seawall for several hours, flooding the NYC subway, knocking out power to the entire system. One train had to be backed out of a tunnel that was filling with water, and hundreds of passengers were rescued from stranded trains. Portions of the Port Authority Trans-Hudson Corporation (PATH) train systems in New Jersey were shut down for ten days, after low points in the rail tunnels flooded and major damage occurred to the control signals. Passengers had to be rescued from a train stalled in the PATH tunnel. Surges only one to two feet higher may have caused massive flooding of the PATH train tunnels. La Guardia Airport was closed due to flooded runways. Roadway flooding was also widespread—FDR Drive in lower Manhattan flooded with 4 feet of water, which stranded more than 50 cars and required scuba divers to rescue some of the drivers. Battery Park Tunnel held six feet of water. Major parkways were flooded in Nassau County, Westchester County, and New Jersey. Mass transit between New Jersey and New York was down for ten days, and the storm did hundreds of millions in damage to the city. The situation was similar in September 1960 during Hurricane Donna, which brought a storm surge of 8.36 feet to the Battery, and flooded lower Manhattan to West and Cortland Streets. The November 25, 1950 Nor'easter brought sustained easterly winds of up to 62 mph to LaGuardia Airport, and pushed a large storm surge up Long Island Sound that breached the dikes guarding the airport, flooding the runways.


Figure 3. Water pours into the Hoboken, New Jersey underground PATH mass transit station during the December 12, 1992 Nor'easter. Image credit: Metro New York Hurricane Transport Study, 1995.


Figure 4. Flooded runways at New York's La Guardia Airport after the November 25, 1950 Nor'easter breached the dikes guarding the airport. Sustained easterly winds of up to 62 mph hit the airport, pushing a large storm surge up Long Island Sound. The storm's central pressure bottomed out at 978 mb. Image credit: Queens Borough Public Library, Long Island Division.

Sea level rise and New York City
According to tide gauge data, sea level at the Battery at the south end of Manhattan has risen about 1 foot since 1900. This is higher than the mean global sea level rise of 7 inches (18 cm) that occurred in the 20th century. Global sea level rise occurs because the oceans are expanding as they heat up, and due to melt water from glaciers. The higher sea level rise in New York is due to the fact the land is sinking along the coast. These processes will continue during the coming century.

The U.N.'s Intergovernmental Panel on Climate Change (IPCC), predicted in 2007 a 0.6 - 1.9 foot global average sea level rise by 2100. However, they did not include melting from Greenland and Antarctica in this estimate, due to the large uncertainties involved. A paper published by Pfeffer et al. (2008) in Science concluded that the "most likely" range of sea level rise by 2100 is 2.6 - 6.6 feet. Three major sea level papers published since the IPCC report was issued in 2007 all agree that the IPCC significantly underestimated the potential sea level rise by 2100. In a 2009 interview with New Scientist magazine, sea level expert/ glaciologist Robert Bindschadler of the NASA Goddard Space Flight Center in Greenbelt, Maryland, commented, "most of my community is comfortable expecting at least a meter (3.28') by the end of this century." Sea level expert Stephan Rahmstorf added, "I sense that now a majority of sea level experts would agree with me that the IPCC projections are much too low." However, he cautioned that the popular media tend to focus on the upper limits of these newer projections (1. 5 - 2.0 meters), and "reaching the upper limits is, by definition, extremely unlikely.""

The sea level rise situation will be worse in areas where ocean currents have a large impact on the local sea level. This is the case along the Northeast U.S. coast, where the balance of forces required to maintain the very strong and narrow Gulf Stream Current means that sea water is sucked away from the coast, lowering the relative sea level from North Carolina northwards. During the coming century, the addition of large amounts of heat and fresh water into the North Atlantic due to higher precipitation, river runoff, and increased melting of glaciers is expected to weaken the Meridional Overturning Circulation (MOC) (also referred to as the thermohaline circulation), a global network of density-driven ocean currents. Weakening the thermohaline circulation will allow the Gulf Stream to spread out, resulting in sea level rise along the Northeast U.S. coast. Hu et al. (2009) found that a slow-down of the Meridional Overturning Circulation by 48% may occur by 2100, resulting in a 0.1 - 0.3 meter (0.25 - 1.0 ft) rise in sea level along the U.S. Northeast coast and Canadian Atlantic coast. This rise would be in addition to global sea level rise from melting glaciers and thermal expansion of the waters. A similar study by Yin et al. (2009) found a slow-down of the Meridional Overturning Circulation of 41% by 2100. New York City was in the region with the highest expected sea level rise from this ocean current effect--a rise of about 0.2 meters (0.75 feet) by the year 2100. If the Atlantic thermohaline circulation were to totally collapse, the authors predict a 4 ft (1.2 meter) rise in sea level along the U.S. Northeast coast solely due to the change in ocean currents. The IPCC predicts that such an abrupt climate change event (rather ridiculously depicted in the movie The Day After Tomorrow) will not occur in the coming century, though.

The future: Stronger hurricanes for New York City?
According to a summary statement endorsed by 125 of the world's top hurricane scientists at the World Meteorological Organization (WMO) Sixth International Workshop on Tropical Cyclones, in San Jose Costa Rica, in November 2006. "it is likely that some increase in tropical cyclone intensity will occur if the climate continues to warm." This makes intuitive sense, since hurricanes are heat engines that convert the heat of the ocean waters into the mechanical energy of wind. Turn up the thermostat, and you increase the energy available to make the strongest storms stronger. One major reason hurricanes weaken quickly when they approach New England is that the coastal waters cool dramatically north of North Carolina. As ocean waters warm during the coming century, hurricanes will be more able to maintain their strength farther to the north. One of the reasons the ECMWF model was simulating a 936 mb Hurricane Irene hitting New Jersey was because ocean temperatures off the mid-Atlantic coast were 1°C (1.8°F) above average during August 2011--the 7th warmest in recorded history. These high ocean temperature were due to the exceptional heat wave that gripped much of the mid-Atlantic during the summer of 2011--every state along the coast from Florida to New Jersey had a summer that ranked in the top four warmest summers since 1895. Such heat waves and warm ocean temperature are expected to become the new normal by mid-century, resulting in increased chances for strong hurricanes to make it to New England.


Figure 5. Summer temperatures along the U.S. Atlantic coast during 2011 ranked as 2nd - 4th warmest on record from Florida to New Jersey, resulting in exceptionally warm waters along the coast for Hurricane Irene to feed off of in late August. Image credit: National Climatic Data Center.

The other major reason that strong hurricanes have trouble making it to New England is that wind shear generally increases as one gets closer to the pole, due to the presence of the powerful winds of the polar jet stream. However, climate change theory predicts that the jet stream should migrate poleward during the coming decades, potentially reducing the amount of wind shear hurricanes arriving in New England will experience. A 2008 study by Archer and Caldeira found that the jet stream moved northwards 125 miles per decade during the 22-year period 1979 - 2001, in agreement with climate change theory. However, the migration of the jet stream northwards may also mean that hurricanes will be less likely to be caught up in a trough of low pressure embedded in the jet stream, resulting in fewer hurricanes swinging northwards to impact New England. At this point, it is hard to say whether or not changes to the jet stream due to climate change will alter the frequency of strong hurricanes reaching New England.

New York City's inadequate sea wall
The floodwalls protecting Manhattan are only five feet above mean sea level. At high tide, the water is only 3.5 feet below the top of the seawall, so clearly Manhattan is going to have a serious storm surge problem by the end of the century if sea level rise reaches the 3-foot plus figure many sea level rise scientists are predicting. As Ben Straus of Climate Central pointed out in a blog post on Irene, "sea level rise will amplify the impact of future hurricanes and Nor'easters. If we replay the 20th century but add an extra foot of sea level at the start (the extra foot we indeed started with in 2000, compared to 1900), about six events would produce higher water levels than the Nor'easter of 1992." Remember, the 1992 Nor'easter crippled the city's transportation system for ten days and caused hundreds of millions in damage. A Category 2 hurricane like the 1821 hurricane would be far worse, and could result in severe global economic consequences. A 15-foot storm surge from such a hurricane would swamp JFK and La Guardia airports. Manhattan would flood north to Canal Street, shutting down Wall Street and New York City's Financial District. The Holland Tunnel, much of the NYC subway system, and the New Jersey PATH mass transit systems would all flood. Many of the power plants that supply the city with electricity might be knocked out, or their docks to supply them with fuel could be destroyed. Nearly half a million people and almost 300,000 jobs lie within the Federal Emergency Management Agency (FEMA) 0.2-percent-annual-chance flood zones that would be inundated. As New York Times columnist Nate Silver wrote, such a disaster would likely cost near $100 billion. Furthermore, he makes the point, "Keep in mind that New York City's annual gross domestic product is about $1.4 trillion, one-tenth of the nation's gross domestic product, so if much of the city were to become dysfunctional for months or more, the damage to the global and domestic economies would be almost incalculable."


Figure 6. The seawall protecting Manhattan at Battery Park is only 5 feet above mean sea level. Tidal range at the Battery is plus or minus 1.5 feet, so at high tide a storm surge of just 3.5 feet is needed to send water over the seawall and into Manhattan.

Flooding of the NYC subway system
The U.S. Federal Transit Administration released a report in October 2011 called, "Flooded Bus Barns and Buckled Rails: Public Transportation and Climate Change Adaptation". The report says that with three feet of sea-level rise, the flooding produced by a 100-year storm at current sea levels will require only a 10-year storm, in other words, a tenfold increase in the frequency of flooding. Even without sea-level rise, a 100-year flood (an 8-foot storm surge) would inundate substantial portions of the subway system, whose tunnels generally lie twenty feet below street level. With sea-level rise though, the flooding occurs more rapidly and is more severe. A 100-year flood with a four foot rise in sea level would flood a large fraction of Manhattan subways, including virtually all of the tunnels crossing into the Bronx beneath the Harlem River and the tunnels under the East River. Flood waters enter the subway tunnels mostly vertically via ventila­tion grates and entrances as the streets flood, but also via inclined rail and road tunnels. Hydraulic computations show complete flooding takes only 40 minutes. Recovery would require obtaining huge quantities of pumps and hoses, awaiting restoration of power to the electrical grid, pumping out the flood waters, cleaning out miles of muddy and debris-filled platforms, stairs, tunnels and trackway, assessing the damage, and repairing problems. Much of the signal equipment and controls in the tunnels would be damged by salt or brackish water and would need to be disassembled, cleaned, and repaired or replaced to avoid corrosion and irreparable long-term damage. This specialized equipment, some of it 100 years old, is difficult to obtain and in many cases no longer manufactured. Researchers estimate a minimum recovery time of three to four weeks to reach 90 percent capacity, although when engineers were presented with the question, they believed that it could take one to two years to recover fully. This also assumes trains were moved to portions of the system with elevations above flood levels, in anticipation of the storm and were thus not damaged. Additional problems could result if the flood waters were contami­nated with toxins. Combined economic and physical damage losses from subway tunnel flooding under a 100-year storm surge were estimated at $58 billion at current sea levels and $84 billion with four feet of sea-level rise, assuming a linear recovery and an estimated subway outage time of three to four weeks.


Figure 7. New York City Subway vulnerability to a 100-year flood of 8 feet, with a 4-foot sea level rise. Blue lines are flooded subway tunnels. Orange areas have elevation less than 30 feet at present. Subway tracks are typically 20 feet below street level. Image credit: New York State Energy Research and Development Authority (NYSERDA), ClimAID: Responding to Climate Change in New York State, Draft Version, 2010.

What to do? Build a storm surge barrier
As I discussed in Part One of this series on U.S. storm surge risk, three cities in New England--Stamford, Providence, and New Bedford--have already built hurricane storm surge barriers that have more than paid for the cost of their construction in damages saved. Many coastal cities will need to substantially improve their flood defenses in coming decades due to rising sea levels. For New York, the best solution is to place three barriers at strategic "choke points"—the Verrazano Narrows, Throgs Neck, and the Arthur Kill, argues Douglas Hill of Stony Brook University's Storm Surge Research Group. I'll present his arguments in a guest post in Part Three of this series on storm surge risk in the U.S., coming up sometime in the next week.

Resources and references
Storm surge barriers: the New England experience: Part One of this series on U.S. storm surge risk.

The National Hurricane Center's Interactive Storm Surge Risk Map, which allows one to pick a particular Category hurricane and zoom in to see the height above ground level a worst-case storm surge may go.

Wunderground's Storm Surge Inundation Maps for the U.S. coast.

Climate Change Adaptation in New York City: Building a Risk Management Response: New York City Panel on Climate Change 2010 Report

Climate change information resources for NYC from Columbia University.

Landstrike is an entertaining fictional account of a Category 4 hurricane hitting New York City.

Colle, B.A., et al., 2008, New York City's vulnerability to coastal flooding: storm surge modeling of past cyclones, Bull. Am. Meteor. Soc. 89, 829–841 (2008).

Hu, A., G. A. Meehl, W. Han, and J. Yin (2009), "Transient response of the MOC and climate to potential melting of the Greenland Ice Sheet in the 21st century", Geophys. Res. Lett., 36, L10707, doi:10.1029/2009GL037998 29 May 2009

Rignot, E., and P. Kanagaratnam (2006), Changes in the velocity structure of the Greenland Ice Sheet, Science, 311, 986. 990.

Yin, J., M.E. Schlesinger, and R.J. Stouffer, 2009, "Model projections of rapid sea-level rise on the northeast coast of the United States", Nature Geoscience 2, 262 - 266 (2009).

Lady Liberty not at risk from a storm surge
As a side note, the Statue of Liberty is not vulnerable to a storm surge, since the good lady stands atop a 65-foot high foundation and 89-foot high granite pedestal. However, the 305' height of the lady's torch above the foundation means the statue will experience winds a full Saffir-Simpson category higher than winds at the surface. The statue is rated to survive a wind load of 58 psf, which is roughly equivalent to 120 mph winds (Category 3 hurricane). However, a mid-strength Category 2 hurricane with 105 mph winds will be able to generate 120 mph winds at a height of 300 feet, and would theoretically be capable of toppling the Statue of Liberty.

Jeff Masters

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I just got this from the BBC, {which we sometimes like to believe is not a Micky Mouse operation,Sometimes,}

http://www.bbc.co.uk/news/science-environment-159 92519

"However, stabilising at 350ppm CO2e is a very demanding target,given that the current concentration is more than 450ppm."

Can you believe that they not only write this stuff but then they put it on their world news, check out the link line above the statement.
The items lead statements was:-

"The world's poorest countries have asked that talks on a new climate deal covering all nations begin immediately."

Member Since: Posts: Comments:
Quoting WxGeekVA:
Getting excited about the nor'easter that is being consistently shown on the GFS for the middle of next week. The 12Z run has very heavy snow over DC at hour 150.

Link

If by very heavy you mean little to none, then yeah.
Member Since: 6 juillet 2010 Posts: 109 Comments: 30282
Cleverbot is saying next hurricane season will be deadly and destructive. It says every single tropical cyclone will impact land, and we'll have at least two Category 5's, in August and September. Additionaly...

Me: Will we see a major hurricane make landfall in the USA next year?

Cleverbot: yes
Member Since: 6 juillet 2010 Posts: 109 Comments: 30282
Getting excited about the nor'easter that is being consistently shown on the GFS for the middle of next week. The 12Z run has very heavy snow over DC at hour 150.

Link
Member Since: 3 septembre 2011 Posts: 13 Comments: 3466
Quoting StormTracker2K:
Lots of rain for you Hydrus over the next week.

I had 4 inches of rain last weekend. We could do without the rain.
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I've been re-reading the blog post a few times and these lines, from it; though simple to understand sum things up so well:-
"New York City's storm surge history.
During the December 12, 1992 Nor'easter, powerful winds from the 990 mb storm drove an 8.5-foot storm surge into the Battery Park on the south end of Manhattan. The ocean poured over the city's seawall for several hours,"
As only remote skeptics would argue against current sea level rises as stated in the blog,the above can only be seen as a foretaste of what is to come, not only through storm conditions in the New York area but in lots of other places as well, {Thailand was mentioned a few days ago.}
There would appear to be no other solution if events play out as the blog states, than to relocate vast areas of many coastal cities. The logistics of this are awesome, the projected losses catastrophic. I would speculate that the first time a disaster like the projected New York situation occurs might also be the first time people start to take the sea rising seriously.A sort of "Natures Warning."
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Goodbye, adios, to the 2011, hurricane season. For us in the "Island of the enchantment", will be remember for the first direct hit of a minimal hurricane Irene since Hurricane Jeanny,2004, and tropical storm Olga in December 11, 2007.
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If anyone needs a 30ft tall christmas tree, there's a perfectly good uprooted pine tree in front of the Univ. of Utah student union building. 69mph gusts on campus last night and the highest so far seems to be 100mph in Centerville, Utah. Heck of a mess we've got here; something like a dozen tipped semis throughout the Wasatch Front.
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Lots of rain for you Hydrus over the next week.

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Quoting TropicalAnalystwx13:

I doubt we'll have El Niño next year...If we do, it won't be until the end of the next year.


There will be El-Nino toward the end of next year as El-nino typically occurs every 3 years. Question will be over the coming weeks is how strong and how soon does this transition occur.
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More rain for already flooded areas..Sign of things to come?
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From early 2010 to now:

Strong La Nia --> Moderate La Nia --> Weak La Nia --> Neutral --> Weak La Nia

Bold = Current
Member Since: 6 juillet 2010 Posts: 109 Comments: 30282
Quoting StormTracker2K:
Gonna be interesting to see what the strength of next years El-Nino will be.


I doubt we'll have El Niño next year...If we do, it won't be until the end of the next year.
Member Since: 6 juillet 2010 Posts: 109 Comments: 30282
Gonna be interesting to see what the strength of next years El-Nino will be.

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Quoting TropicalAnalystwx13:

You've not been here for a full season yet...Wait until next year. I've learned so much just listening to other people on this blog.


This is my 3rd season on the blog, but my first as a posting member. I totally agree with you on that, and hopefully there will be many more seasons to come. On here I learned of other sites with computer models as well as how to eat crow when I was wrong. I'm not leaving for the winter but I will be commenting less.
Member Since: 3 septembre 2011 Posts: 13 Comments: 3466
It is going to be a very warm December here in FL. Enjoy this cool day today because it will be gone for atleast 2 weeks maybe more.

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Bye, bye tropical season, welcome to December 1st as we begin Meteorological Winter 2011-2012!

Dr Jeff,
Thanks, you sure brought to light some serious concerns, with this well-researched post. However -

"our most reliable hurricane forecasting model--the European (ECMWF) model"

Okay, a lil nit-picking and certainly takes nothing away from the important points you've illustrated well... Based on the performance of the ECMWF compared to the GFS this past season on several storms, I sure take issue with that model being deemed "our most reliable"... Putting aside intensity forecasts which are frequently wrong by everyone, the GFS was closer and more consistent, especially with the development / track of several storms - three that come to mind, Irene, Lee, and particularly that undeclared subtropical sfc low that affected E FL around October 8-9th. With the GFS and ECMWF at great odds for days leading up to the event, every NWS forecast office in Florida chose to discard the GFS as an outlier / buy into the ECMWF solution of E Gulf development, leading to seriously blown forecasts when the sfc low developed near N Bahamas / lifted toward E FL, much as the GFS had long been indicating (using a consensus of multi-cycle runs). Admittedly, this was a tough forecast to call.

Also noted with Irene, the ECMWF consistently maintained a more westward bias bringing Irene farther inland / sooner, which proved in error - the GFS solution was far more accurate. Both models struggled with the complicated forecast of TS Lee, however once again the ECMWF showed a WWD bias, insisting it would track into S / S Cen TX while the GFS largely favored it into Louisiana and also closely depicted the interaction with the persistent ULL (that likely lead to Lee transitioning from initially a high-sheared TS into a subtropical storm as it merged / co-located with the ULL, as evidenced both in structure and wind field characteristics).

That said, there's good reason why the NHC in a majority of forecast discussions (and daily with NWS AFD's) prudently splits the difference between the two model solutions, which overall, are usually in reasonable agreement by the time it matters most - I believe the correct view is to state the GFS and ECMWF remain our TWO most reliable models! Despite the hype on the euro's performance from certain sources, I see no proof of it being our single "most reliable".
Just a thought...

G'day!
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Quoting SPLbeater:
I have learned a good amount of knowledge on this blog to add with what i already have =P

You've not been here for a full season yet...Wait until next year. I've learned so much just listening to other people on this blog.
Member Since: 6 juillet 2010 Posts: 109 Comments: 30282
Member Since: 4 août 2011 Posts: 46 Comments: 4481
I have learned a good amount of knowledge on this blog to add with what i already have =P
Member Since: 4 août 2011 Posts: 46 Comments: 4481
and just as expected, even with 90L still existing the NHC dont do nothin. lol. just so yal know, SPLbeater found where to get the ASCAT passes and will now make better interpretations =P
Member Since: 4 août 2011 Posts: 46 Comments: 4481



New Jersey Severe Storm

Major Disaster Declared November 30, 2011 (DR-4048) [ En Español ]



Im in the Mood...

Member Since: 3 juillet 2005 Posts: 415 Comments: 125681
Quoting TropicalAnalystwx13:

Here you go, Taz:




thank you
Member Since: 21 mai 2006 Posts: 5089 Comments: 114072






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Quoting JNCali:
I hate freezing fog... it confuses me, I'm used to the warm friendly fog in SoCal .. this stuff is dangerous.. and what are ice pellets? they are in the forecast for Monday?? is it Hail? freezing drizzle? This weather learning curve is a bit steeper than anticipated...
Your gonna luv,em...
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Quoting Neapolitan:
The Western storm some of us were talking about last night is nasty, and getting nastier:

--Wind gusts of up to 100 mph have been felt in some places.

--Albuquerque is expecting a "serious high wind event today" (followed by "significant" snow into the weekend).

--Southern California is experiencing its worst Santa Ana wind event in several years, with many toppled trees and widespread power outages.

And so on all across the Southwest and along the central and southern Rockies. A good day to stay off the roads, I think...


carbon emissions and climate change is really causing issues out west with all that wind...we've reached a tipping point of no return, were gonna blow off the planet

sarcasm flag:ON
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The Western storm some of us were talking about last night is nasty, and getting nastier:

--Wind gusts of up to 100 mph have been felt in some places.

--Albuquerque is expecting a "serious high wind event today" (followed by "significant" snow into the weekend).

--Southern California is experiencing its worst Santa Ana wind event in several years, with many toppled trees and widespread power outages.

And so on all across the Southwest and along the central and southern Rockies. A good day to stay off the roads, I think...
Member Since: 8 novembre 2009 Posts: 4 Comments: 13296
Quoting JNCali:
I hate freezing fog... it confuses me, I'm used to the warm friendly fog in SoCal .. this stuff is dangerous.. and what are ice pellets? they are in the forecast for Monday?? is it Hail? freezing drizzle? This weather learning curve is a bit steeper than anticipated...


ice pellets are like sleet...they are what they sound like, lol. like rain falling, but freezes BEFORE it gets to the ground:)
Member Since: 4 août 2011 Posts: 46 Comments: 4481
Quoting hydrus:
Good evening Aussie..Glad to see its warming up nicely down under. It was 19 degree,s with freezing fog here on the plateau. 45 car pile up just east of me..Winter is showing its dangerous side already.
I hate freezing fog... it confuses me, I'm used to the warm friendly fog in SoCal .. this stuff is dangerous.. and what are ice pellets? they are in the forecast for Monday?? is it Hail? freezing drizzle? This weather learning curve is a bit steeper than anticipated...
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Quoting Tazmanian:




your showing us nothing

Here you go, Taz:

Member Since: 6 juillet 2010 Posts: 109 Comments: 30282
Quoting AussieStorm:

You linked to this blog..... lol

Oh, lol.

Link
Member Since: 6 juillet 2010 Posts: 109 Comments: 30282
Quoting AussieStorm:

You linked to this blog..... lol
Good evening Aussie..Glad to see its warming up nicely down under. It was 19 degree,s with freezing fog here on the plateau. 45 car pile up just east of me..Winter is showing its dangerous side already.
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Quoting TropicalAnalystwx13:

Yeah, it was on the "Active 2011 hurricane season breaks 'Hurricane Amnesia'" when it was released a few days ago.

You linked to this blog..... lol
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Quoting TropicalAnalystwx13:
The latest GFS transitions the NAO to negative towards the middle of December. This would bring cold air down to the Eastern United States, even if it is only briefly.





your showing us nothing
Member Since: 21 mai 2006 Posts: 5089 Comments: 114072
MONTHLY TROPICAL WEATHER SUMMARY
NWS NATIONAL HURRICANE CENTER MIAMI FL
800 AM EST THU DEC 1 2011

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

ONE TROPICAL STORM...SEAN...FORMED DURING THE MONTH OF NOVEMBER. ON
AVERAGE...A NAMED STORM FORMS DURING NOVEMBER ABOUT ONCE EVERY
OTHER YEAR.

TROPICAL CYCLONE ACTIVITY IN THE ATLANTIC BASIN DURING 2011 WAS
ABOVE AVERAGE. THERE WERE 19 TROPICAL STORMS...INCLUDING AN UNNAMED
STORM DURING SEPTEMBER THAT WAS ADDED DURING THE ROUTINE POST-
ANALYSIS OF DATA FROM THE SEASON. POST-ANALYSIS ALSO REVEALED
THAT NATE REACHED HURRICANE STRENGTH DURING ITS LIFETIME. OF THE 19
STORMS...7 BECAME HURRICANES...AND 3 BECAME MAJOR HURRICANES. ONE
TROPICAL DEPRESSION ALSO FORMED THAT DID NOT REACH TROPICAL STORM
STRENGTH. THE LONG-TERM AVERAGES FOR THE BASIN ARE 11 NAMED
STORMS...6 HURRICANES AND 2 MAJOR HURRICANES. IN TERMS OF
ACCUMULATED CYCLONE ENERGY...ACE...WHICH MEASURES THE COMBINED
STRENGTH AND DURATION OF TROPICAL STORMS AND HURRICANES...2011 WAS
ABOVE NORMAL...WITH A VALUE OF 132 PERCENT OF THE LONG-TERM MEDIAN.

REPORTS ON INDIVIDUAL CYCLONES...WHEN COMPLETED...ARE AT THE WEB
SITE OF THE NATIONAL HURRICANE CENTER...USE LOWER-CASE LETTERS...
HTTP://WWW.NHC.NOAA.GOV/2011ATLAN.SHTML

REPORTS ON SYSTEMS WITH AN ASTERISK NEXT TO THEIR NAME HAVE BEEN
FINALIZED AS OF 1 DECEMBER.

SUMMARY TABLE

NAME DATES MAX WIND (MPH)
------------------------------------------------- ---
TS ARLENE 29 JUN-1 JUL 65
TS BRET 17-22 JUL 65
*TS CINDY 20-22 JUL 70
*TS DON 27-30 JUL 50
TS EMILY 1-7 AUG 50
*TS FRANKLIN 12-13 AUG 45
*TS GERT 13-16 AUG 65
TS HARVEY 19-22 AUG 60
MH IRENE 20-28 AUG 120
TD TEN 25-26 AUG 35
TS JOSE 28-29 AUG 45
MH KATIA 29 AUG-10 SEP 135
TS UNNAMED 1-2 SEP 45
TS LEE 2-5 SEP 60
H MARIA 6-16 SEP 80
*H NATE 7-11 SEP 75
MH OPHELIA 21 SEP-3 OCT 140
H PHILIPPE 24 SEP-9 OCT 90
H RINA 23-28 OCT 110
TS SEAN 8-11 NOV 65

$$
HURRICANE SPECIALIST UNIT

Graphic not available for the 2011 Atlantic season through November.
Member Since: 6 juillet 2010 Posts: 109 Comments: 30282
Quoting AussieStorm:

Has it, NOAA Just released it.

Yeah, it was on the "Active 2011 hurricane season breaks 'Hurricane Amnesia'" when it was released a few days ago.
Member Since: 6 juillet 2010 Posts: 109 Comments: 30282
Quoting TropicalAnalystwx13:

That's been out for days.

Has it, NOAA Just released it.
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Quoting AussieStorm:
Just released, 2011 Hurricane season GOES-13.


That's been out for days.
Member Since: 6 juillet 2010 Posts: 109 Comments: 30282
Just released, 2011 Hurricane season GOES-13.

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The latest GFS transitions the NAO to negative towards the middle of December. This would bring cold air down to the Eastern United States, even if it is only briefly.

Member Since: 6 juillet 2010 Posts: 109 Comments: 30282
Where's my great big arctic blast into the Deep South?

Preferably with a nice, deep, low tracking slowly across the north cent GOM from west to east?



One can dream!
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Quoting NCHurricane2009:
Also while on the topic...I have the same question about 99L earlier this month. Why wasn't it classified as a subtropical cyclone either?

Both of them were Extratropical/Frontal in nature instead of Subtropical/Tropical.
Member Since: 6 juillet 2010 Posts: 109 Comments: 30282
http://www.youtube.com/watch?v=-sxUX3CNjmg
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For anyone who's been following them over the last few days, I just finished my report on Rina.

Hurricane Rina

October 23 - October 28

Rina was a Category 2 hurricane that made landfall in the Yucatan Peninsula as a tropical storm, then turned eastward and dissipated.

A cold front moved into the Gulf of Mexico on October 18, enhancing shower activity across the western Caribbean Sea. Convection increased the next day to the east of Honduras and Nicaragua, but this activity showed little signs of organization. A weak tropical wave crossed the coast of Africa on October 11. The wave was difficult to track on satellite imagery as it marched westward across the tropical Atlantic for the next ten days. Extrapolation and continuity suggest that this wave reached the western Caribbean on October 21. This could have resulted in the abrupt increase in convection that was observed that day to the east of the Nicaraguan coast. A low-level circulation developed later that day about 150 miles east of the coast of Nicaragua, although southeasterly shear kept the deepest convection and strongest winds confined to the western end of the gyre. Despite the shear, the low gradually deepened as it moved northward, becoming a tropical depression near 1800 UTC October 23 while centered about 120 miles northeast of the Honduras/Nicaragua border. The depression became a tropical storm near 0000 UTC October 24.

Rina moved northward while undergoing a brief period of rapid intensification -- by 1500 UTC that day, satellite data indicates that Rina became a hurricane while located about 205 miles southwest of Grand Cayman. Hours later, this was confirmed by a reconnaissance aircraft, which showed surface winds in excess of hurricane force. Further strengthening ensued, and Rina became a Category 2 hurricane near 0600 UTC October 25. At this time, the hurricane had already turned west-northwest amidst a building ridge over the Gulf of Mexico. Rina continued to slowly intensify as it moved slowly westward toward Belize and the Yucatan Peninsula, and the hurricane reached its estimated peak of 95 kt near 2100 UTC October 25, when geostationary satellite imagery confirmed the existence of a small eye. At that time, Rina was centered about 275 miles east-southeast of Chetumal, Mexico.

Shortly afterward, the eye disappeared from satellite, although it remained well-defined in passive microwave imagery (not shown), and in reconnaissance data. After around 0000 UTC October 26, Rina encountered increasing southwesterly shear associated with an amplifying trough over the southern United States. In addition, the hurricane appears to have entrained some drier air during this time. Consequently, the central pressure began to slowly rise, although the hurricane did not decrease in intensity until around 1200 UTC that day. Rina continued to weaken, dropping down to tropical storm status near 0600 UTC October 27 while approaching the Yucatan Peninsula. Rina passed just west of Cozumel late that day, and made landfall along the mainland portion of the Yucatan Peninsula near Playa del Carmen shortly after 0000 UTC October 28. Rina continued to weaken, and became a tropical depression near 1200 UTC, with all of the deep convection confined about 150 miles northeast of the exposed low-level center. About three hours later, Rina dissipated. The remnant low departed the coast near Cancun during this time as well. By this time, Rina was moving eastward in the mid-latitude flow associated with the aforementioned trough.

Void of convection, the shallow vortex eventually turned south, southeast, and then southwest in the low-level flow associated with a building ridge over the Gulf of Mexico. Rina's mid-level circulation continued northeastward across south Florida, ultimately becoming absorbed into a vigorous extratropical low pressure system which brought significant early season snowfall to portions of the mid-Atlantic and New England.
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Quoting Skyepony:


This ASCAT is just a few hours old.. Hardly well defined..


The swirl has run back up under some convection since. Looks more interesting now.


Haha...I knew my earlier comment would cause someone to post an ASCAT pass...thanks for that...

I sort of see a NEARLY closed-circulation in that ASCAT pass (at least developing) around 27.5N 60W....right in the midst of the yellow circle currently in the Tropical Weather Outlook...and I know NEARLY closed doesn't cut it for classifying a system. This might be why this wasn't classified so far...

I thought I saw a low-level swirl on the satellite imagery earlier this afternoon (i.e. a closed circulation)...but I guess this ASCAT pass proves that "swirl" does not necessarily mean fully-closed surface circulation.
Member Since: 15 septembre 2009 Posts: 391 Comments: 3519
201. Skyepony (Mod)
04:53 GMT le 01 décembre 2011
Quoting NCHurricane2009:
Why wasn't 90L classified? I have been watching this system coming together for the last days...and it has a well-defined LLC....

Its not tropical...but I thought this should be classified as a subtropical depression (or subtropical storm depending on the wind strength).

P.S....both Jose AND 90L have well-defined surface circulations....


This ASCAT is just a few hours old.. Hardly well defined..


The swirl has run back up under some convection since. Looks more interesting now.
Member Since: 10 août 2005 Posts: 156 Comments: 36156
200. NCHurricane2009
04:48 GMT le 01 décembre 2011
Fun fact....

Did you know that subtropical systems like 90L & 99L are often triggered by strong non-tropical systems over the eastern US?

For instance today we have that strong frontal system over the eastern US...warm air advection ahead of that system caused a massive upper ridge to amplify over the western Atlantic. That amplified upper ridge can cause an upper trough over the central Atlantic to develop a closed cut-off upper low circulation...with divergence northeast of the cut-off upper low generatinng the surface low that becomes a subtropical cyclone....
Member Since: 15 septembre 2009 Posts: 391 Comments: 3519

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