NOAA's forecast: a very active, possibly hyperactive Atlantic hurricane season
The National Oceanic and Atmospheric Administration (NOAA) issued its 2010 Atlantic hurricane season forecast today. NOAA forecasts a very active and possibly hyperactive season. They give an 85% chance of an above-normal season, a 10% chance of a near-normal season, and just a 5% chance of a below-normal season. NOAA predicts a 70% chance that there will be 14 - 23 named storms, 8 - 14 hurricanes, and 3 - 7 major hurricanes, with an Accumulated Cyclone Energy (ACE) in the 155% - 270% of normal range. If we take the midpoint of these numbers, NOAA is calling for 18.5 named storms, 11 hurricanes, 5 major hurricanes, and an ACE index 210% of normal. A season with an ACE index over 175% is considered "hyperactive." An average season has 10 named storms, 6 hurricanes, and 2 intense hurricanes. The forecasters note that in regards to the oil spill in the Gulf of Mexico,
"Historically, all above normal seasons have produced at least one named storm in the Gulf of Mexico, and 95% of those seasons have at least two named storms in the Gulf. Most of this activity (80%) occurs during August-October. However, 50% of above normal seasons have had at least one named storm in the region during June-July."
The forecasters cited the following main factors that will influence the coming season:
1) Expected above-average SSTs in the hurricane Main Development Region (MDR), from the Caribbean to the coast of Africa. SSTs in the MDR are currently at record levels, and the forecasters note that several climate models are predicting record or near-record SSTs during the peak portion of hurricane season (August - October.) "Two other instances of very warm SSTs have been observed in the MDR during February-April (1958 and 1969). In both years, the SST anomaly subsequently decreased by roughly 50% during the summer months. For 2010, although the record SST departures may well decrease somewhat, we still expect a continuation of above average SSTs throughout the Atlantic hurricane season. "
2) We are in an active period of hurricane activity that began in 1995, thanks to a natural decades-long cycle in hurricane activity called the Atlantic Multidecadal Oscillation (AMO). "During 1995-2009, some key aspects of the tropical multi-decadal signal within the MDR have included warmer than average SSTs, reduced vertical wind shear and weaker easterly trade winds, below-average sea-level pressure, and a configuration of the African easterly jet that is more conducive to hurricane development from tropical waves moving off the African coast. Many of these atmospheric features typically become evident during late April and May, as the atmosphere across the tropical Atlantic and Africa begins to transition into its summertime monsoon state."
3) There will either be La Niña or neutral conditions in the Equatorial Eastern Pacific. El Niño is gone, and it's demise will likely act to decrease wind shear over the tropical Atlantic, allowing more hurricanes to form. "La Niña contributes to reduced vertical wind shear over the western tropical Atlantic which, when combined with conditions associated with the ongoing high activity era and warm Atlantic SSTs, increases the probability of an exceptionally active Atlantic hurricane season (Bell and Chelliah 2006). NOAA's high-resolution CFS model indicates the development of La Niña-like circulation and precipitation anomalies during July."
How accurate are the NOAA seasonal hurricane forecasts?
A talk presented by NHC's Eric Blake at the 2010 29th Annual AMS Conference on Hurricanes and Tropical Meteorology studied the accuracy of NOAA's late May seasonal Atlantic hurricane forecasts, using the mid-point of the range given for the number of named storms, hurricanes, intense hurricanes, and ACE index. Over the past twelve years, a forecast made using climatology was in error, on average, by 3.6 named storms, 2.5 hurricanes, and 1.7 intense hurricanes. NOAA's May forecast was not significantly better than climatology for these quantities, with average errors of 3.5 named storms, 2.3 hurricanes, and 1.4 intense hurricanes. Only NOAA's May ACE forecast was significantly better than climatology, averaging 58 ACE units off, compared to the 74 for climatology. Using another way to measure skill, the Mean Squared Error, May NOAA forecasts for named storms, hurricanes, and intense hurricanes had a skill of between 5% and 21% over a climatology forecast (Figure 2). Not surprisingly, NOAA's August forecasts were much better than the May forecasts, and did significantly better than a climatology forecast.
Figure 1. Mean absolute error for the May and August NOAA seasonal hurricane forecasts (1999 - 2009 for May, 1998 - 2009 for August), and for forecasts made using climatology from the past five years. A forecast made using climatology was in error, on average, by 3.6 named storms, 2.5 hurricanes, and 1.7 intense hurricanes. NOAA's May forecast was not significantly better than climatology for these quantities, with average errors of 3.5 named storms, 2.3 hurricanes, and 1.4 intense hurricanes. Only NOAA's May ACE forecast was significantly better than climatology, averaging 58 ACE units off, compared to the 74 for climatology. Image credit: Verification of 12 years of NOAA seasonal hurricane forecasts, National Hurricane Center.
How do NOAA's seasonal hurricane forecasts compare to CSU and TSR?
Two other major seasonal hurricane forecasts will be released next week. On June 2, Phil Klotzbach and Bill Gray of Colorado State University (CSU) issue their forecast, and the British firm Tropical Storm Risk (TSR) will issue their outlook on June 4. A three-way comparison of the forecast accuracy of the three groups' forecast (Figure 2) reveals that all three organizations enjoy some success at making accurate seasonal forecasts, with NOAA and CSU making the best late May/early June forecasts overall. While the skill of these forecasts is low, they are useful for businesses such as the insurance industry.
Figure 2. Comparison of the percent improvement over climatology for May and August seasonal hurricane forecasts for the Atlantic from NOAA, CSU and TSR from 1999-2009 (May) and 1998-2009 (August). using the Mean Squared Error. Image credit: Verification of 12 years of NOAA seasonal hurricane forecasts, National Hurricane Center.
Central American disturbance
The Atlantic is currently quiet, with the non-tropical storm (90L) that we were watching now no longer a concern. There is an area of disturbed weather (90E) just off the Pacific coast of Mexico that will be a major concern for southern Mexico and much of Central America over the next 3 - 4 days. The disturbance will bring heavy rains to Central America during the remainder of the week, potentially bringing serious flooding rains to portions of Mexico, Guatemala, El Salvador, Honduras, and Nicaragua. NHC is giving the disturbance a high (>60% chance) of the disturbance developing into a tropical depression by Saturday. There is the potential for disturbed weather accompanying the disturbance--or the disturbance itself--to push into the Western Caribbean early next week and pose a threat to develop into a tropical depression. While there is high wind shear over the northern Caribbean, shear may be low enough to allow development should the disturbance stay in the southern reaches of the Caribbean. None of the models are currently calling for this to happen, and I think the threat is low. Any storm that develops in the Caribbean in the coming week would get steered to the northeast and will not pose a threat to the Gulf of Mexico. Wunderbloggers Weather456 and StormW have more on the tropics.
Figure 3. Visible satellite image of the Central American disturbance 90E this morning.
Oil threat for the coast of Louisiana to decrease this weekend
Light winds from the north or west are expected to prevail across the northern Gulf of Mexico through Friday, resulting in a lessened threat of oiling to the Louisiana shoreline, according to the latest trajectory forecasts from NOAA. However, the latest runs of the GFS model indicate a return to onshore winds out of the southwest for most of next week, which will likely bring oil back towards shore. At greatest risk will be the coast of Louisiana, and there will be heightened risk to Mississippi, Alabama, and the Florida Panhandle. I'll a have a more in-depth discussion of the oil spill forecast in Friday's blog.
Oil spill resources
My post, What a hurricane would do the Deepwater Horizon oil spill
My post on the Southwest Florida "Forbidden Zone" where surface oil will rarely go
My post on what oil might do to a hurricane
NOAA trajectory forecasts
Deepwater Horizon Unified Command web site
Oil Spill Academic Task Force
University of South Florida Ocean Circulation Group oil spill forecasts
ROFFS Deepwater Horizon page
Surface current forecasts from NOAA's HYCOM model
Synthetic Aperture Radar (SAR) imagery from the University of Miami
Join the Hurricane Haven with Dr. Jeff Masters: a new Internet radio show
Beginning next week, I'll be experimenting with a live 1-hour Internet radio show called "Hurricane Haven." The show will be aired at 4pm EDT on Tuesdays, with the first show June 1. Listeners will be able to call in and ask questions. Some topics I'll cover on the first show:
1) What's going on in the tropics right now
2) Preview of the coming hurricane season
3) How a hurricane might affect the oil spill
4) How the oil spill might affect a hurricane
5) New advancements in hurricane science presented at this month's AMS Conference on Hurricanes and Tropical Meteorology
6) Haiti's vulnerability to a hurricane this season
I hope you can tune in to the broadcast, which will be at http://www.wunderground.com/wxradio/wubroadcast.h tml. If not, the show will be recorded and stored as a podcast.
Jeff Masters
Reader Comments
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...we choose to go to the moon and do the other things...not because they are easy, but because they are hard.
...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 345 PM EDT
FOR NORTHEASTERN MONTGOMERY...SOUTHEASTERN MIAMI AND NORTHWESTERN
GREENE COUNTIES...
AT 258 PM EDT...THE PUBLIC REPORTED 1.25 INCH DIAMETER HAIL AT TIPP
CITY. RADAR INDICATED THAT THIS SEVERE THUNDERSTORM REMAINS CAPABLE
OF PRODUCING QUARTER SIZE HAIL AND WINDS TO 60 MPH. THIS STORM WAS
LOCATED NEAR TIPP CITY...MOVING SOUTH AT 10 MPH.
LOCATIONS IMPACTED INCLUDE...
VANDALIA...HUBER HEIGHTS...WRIGHT-PATTERSON AFB...NORTHRIDGE...
FAIRBORN AND DAYTON.
So yeah I should probably come back in a bit instead and try to get involved for once when this is over.
Now I have another image in my head...
Every one of them have their own scenario for this system right now! :P
What is the smallest storm ever recorded?
I will take record-breaking storms for $200 Alex
lol we need to keep quiet about play dough or else BP will start calling it that and try to market it -.-
POLO!
thats not vinegar its pickle juice
Where is that from? Where might I find one of those maps for my area?
well now we are gonna have giant play doh blobs in the gulf and obama will be on the news bellering "just sweep up the dam play doh!!"
BP's "Biota Doh", made with real pieces of GOM biota...get it while it lasts
Hey how do you get those sfwmd charts to post? I've tried time and again on my blog. Everytime I put it in the image box, and hit enter, instead of asking for width and height it just goes away. Do you gotta do something different with those?
Link
Click on your area on the US map. In the left column, go to mesoanalysis, scroll to the bottom under all the maps and click convective available potential energy.
I am not sure if the NWS does this for all areas though.
Which brings me to this, in reference to the quote below...
The hurricane season DOES NOT DEPEND ON THE LA NINA. The La Nina, and the hurricane season, just like last year's El Nino and the hurricane season, are both being caused by the same global phenomena. The Earth has warmed for the past 20-30 years. The natural tendency for the Earth to fight back and try to cool is underway. The swing back of the PDO to colder in the longer term means El Ninos can't last. They are there because of the reactive process of the cooling, (the El Nino this past year was a reaction to the strong La Nina, which started the new cold PDO and the low solar activity, which encourages Ninos anyway). However, because of the turnaround in the global temperature that is occurring, the place where it is going to stay warmest longest is the place where the turnaround is lagging, and that is the Atlantic basin, which has to react to the Pacific. So what happens is the Atlantic stays warm. Somehow, the Earth has to balance out the imbalance, and it does so by creating more tropical activity. But the overall driver here is NOT THE LA NINA. It is a by-product, the same as the hurricane season is, of a larger signal that is taking place.
The NOAA argument that there will be more because of La Nina does not hold water! Why? Because we already have an example of a the 2005 season with no La Nina and 28 storms! We have examples of El Ninos and above average years (1969, 2004, and to some extent, 2002). The other problem is that the La Nina is coming on, and it's a slam dunk now. In fact, remember the forecast I made about a week ago for the SOI, how it was going to go up this week? Well, last night we had a single day of plus 32, the second highest positive daily of the year.
But this is how I am figuring this stuff out so early. It has to do with my ideas on the AGW debate, and the research done there, that as a by-product, is helping me to figure out the "rhythm" of the overall pattern. The Enso is a global phenom, but my argument with NOAA is that they are broad-brushing this without acknowledging the real power behind the throne, and that is the basic knowledge that the Earth in cooling cycles cools Pacific first, leaving the Atlantic warm and ripe for such events as we have been seeing.
One may ask, well what about the '30s-'50s? There weren't as many storms. Well, first of all, the 14 majors that hit from Fla. up the East Coast in 20 years has not occurred, yet, but we are in the time of the cycle that would promote that. Second, my suspicion is that we may have been warmer in the northern areas then, than we are now. I can't prove that, I don't have the satellite data, but the way to create a lot of storms is to BUNDLE heat in the tropical breeding grounds, not spread out heat all over the place. If it's too warm in the northern areas, then the need to transfer heat is not there. It's why this season could be less... if the water does NOT STAY COLD between the warmth in the north and cool in the central Atlantic, that is seen in the tripole. One has to have an area of sustained cooler water to incubate the areas to the south to breed the storms. We showed that before the season last year, the idea of more warm water farther north, cooler south. In addition, the stronger La Nina argument does not hold water without the Atlantic being in the right mode. Afterall, the La Nina came on gangbusters in '07, and the season did not turn out that bad. In fact, it shifts tracks south.
This is another reason why I am so into the AGW debate, because in knowing the drivers, or at least examining things, you can come up with ideas beforehand. And this doesn't happen overnight. I am 54 years old... when I was 44, I did not think this way, but constant research to find and answer, with the risk that it would lead me nowhere, was needed. So one stands on what one believes, based on what they prepared for. That others don't look, or think about these things, can't be a concern for me, though I believe over the coming years they will.
In any case, if it is a big season this year, it's not the La Nina. The La Nina this year, the El Nino last year, were not the cause of the season, but both results of larger overall changes that are driving them. Over the years, I feel the weather will prove my point.
By the way, the final line of the NOAA press release is fine by me. "NOAA's mission is to understand and predict changes in the Earth's environment, from the depths of the ocean to the surface of the sun, and to conserve and manage our coastal and marine resources."
Sounds much less Big Brotherish...
by joe
It is not
a spill
It is an
uncontrollable
leak
Yeah, compared to south fl, the NWS of Peachtree City and Atlanta have nothing on the left column. Oh well.
Current:
144 hours:
At the beginning of the link it reads HTTPS. Before you click ok remove the S from the link address so you have HTTP.
Craftsman 1-5/16 box end saves the Gulf
Now I could be totally off on this, but is that spin I see near El Salvador what the models are taking into the Atlantic? I know the main system's farther west and consolidating nicely, but I want to make sure I'm seeing things right.
elaborate??
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