NOAA predicts a near-normal Atlantic hurricane season

By: Dr. Jeff Masters , 9:17 PM GMT on May 24, 2012

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NOAA forecasts a near-normal Atlantic hurricane season in 2012, in their May 24 outlook. They give a 50% chance of a near-normal season, a 25% chance of an above-normal season, and a 25% chance of a below-normal season. They predict a 70% chance that there will be 9 - 15 named storms, 4 - 8 hurricanes, and 1 - 3 major hurricanes, with an Accumulated Cyclone Energy (ACE) 65% - 140% of the median. If we take the midpoint of these numbers, NOAA is calling for 12 named storms, 6 hurricanes, 2 major hurricanes, and an ACE index 102% of normal. This is very close to the 1981 - 2010 average of 12 named storms, 6 hurricanes, and 3 major hurricanes. Hurricane seasons during the active hurricane period 1995 - 2011 have averaged 15 named storms, 8 hurricanes, and 4 major hurricanes, with an ACE index 153% of the median. Only five seasons since 1995 have not been above normal--including four El Niño years (1997, 2002, 2006, and 2009), and the neutral 2007 season.


Figure 1. The strongest Atlantic hurricane of 2011, Ophelia, as seen at 1:40 pm EDT October 1, 2011. At the time, Ophelia was a Category 3 hurricane with 120 mph winds. At 11 pm that night, Ophelia peaked at Category 4 strength with 140 mph winds. Image credit: NASA.

The forecasters cited the following main factors that will influence the coming season:

1) Near-average sea surface temperatures (SSTs) are expected in the hurricane Main Development Region (MDR), from the Caribbean to the coast of Africa between between 10°N and 20°N. SSTs in the MDR during April were near-average, and are expected to remain so during hurricane season, based on current observations, climatology, and long-range model forecasts.

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 1995-2010, some key aspects of the tropical multi-decadal signal within the MDR have included reduced vertical wind shear and weaker easterly trade winds, below-average sea-level pressure, a configuration of the African easterly jet that is more conducive to hurricane development from tropical cloud systems (aka Easterly waves) moving off the African coast, and warmer than average SSTs."

3) An El Niño event may occur this year: "Another climate factor known to significantly impact Atlantic hurricane activity is the El Niño-Southern Oscillation (ENSO.) The three phases of ENSO are El Niño, La Niña, and ENSO-Neutral. El Niño events tend to suppress Atlantic hurricane activity, while La Niña events tend to enhance it (Gray 1984). If El Niño fails to develop, the probability of an above-normal Atlantic hurricane season will be higher and the actual seasonal activity will likely be toward the upper end of our predicted ranges." There is currently of lot of uncertainty whether or not an El Niño event will develop in time for the August - September - October peak of hurricane season--the latest NOAA El Niño discussion is giving a 41% chance of an El Niño event during hurricane season, and a 48% chance of neutral conditions.

4) NOAA is increasingly using output from ultra-long range runs of the computer forecast models we rely on to make day-to-day weather forecasts, for their seasonal hurricane forecasts: "The outlook also takes into account dynamical model predictions from the NOAA Climate Forecast System (CFS), the European Centre for Medium Range Weather Forecasting (ECMWF), the United Kingdom Meteorology (UKMET) office, and the EUROpean Seasonal to Inter-annual Prediction (EUROSIP) ensemble. These models show large spreads in the ENSO forecasts for ASO, ranging from ENSO-Neutral to a moderate-strength El Niño episode. As a result, their forecasts for the Atlantic hurricane season also show a considerable spread, ranging from slightly above normal to slightly below normal."

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. Not surprisingly, NOAA's August forecasts were much better than the May forecasts, and did significantly better than a climatology forecast.


Figure 2. 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.

I'll have an update on Hurricane Bud and Invest 94L Friday morning.

Jeff Masters

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Quoting MississippiWx:


Going to depend on how much shear is around and if it can stay offshore long enough. Water should be warmer for 94L than they were for Alberto. The air to the west is extremely dry as well and will need to moisten over the next few days for high end TS/hurricane strength to be achieved. Conditions just aren't too favorable yet. It's going to be fun to watch, though.



Do you agree with my statement that a track towards North Florida, Southern Georgia seems the most likely?
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Quoting TropicalAnalystwx13:
I could see an upper-end tropical storm out of this.

Maybe a minimal hurricane if it tries hard enough.



Going to depend on how much shear is around and if it can stay offshore long enough. Water should be warmer for 94L than they were for Alberto. The air to the west is extremely dry as well and will need to moisten over the next few days for high end TS/hurricane strength to be achieved. Conditions just aren't too favorable yet. It's going to be fun to watch, though.

Member Since: July 15, 2006 Posts: 17 Comments: 10284
Quoting BrickellBreeze:


What about the dynamic?

Member Since: July 6, 2010 Posts: 113 Comments: 32348
426. Skyepony (Mod)
Member Since: August 10, 2005 Posts: 179 Comments: 38327
Quoting ncstorm:
00z Statistical Models



What about the dynamic?
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Member Since: July 6, 2010 Posts: 113 Comments: 32348
Quoting GTcooliebai:
Hey look the # 7




The rain season is starting up man, we might end up getting serious rainfall in the long term, especially if that low does sink southwest back towards Tampa eventually, southwest flow around low pressure off the gulf with deep moisture over warm waters is a classic setup for bands of torrential rain and strong thunderstorms. This is still days out so a lot can happen and change but overall it looks good for us rainfall wise through the long term. I'm quite certain drought relief is coming, well the local area already had some, some of us got several inches tonight locally :)




BTW the high was 97 at my house today!
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Icing down a six pack o FRESCA

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Quoting Thrawst:


really? You are obvs too conservative. :P


Fine I will increase my predictions....

6-31 storms
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00z Statistical Models

Member Since: August 19, 2006 Posts: 13 Comments: 15746
Quoting Thundercloud01221991:


I am thinking 5-30 storms


really? You are obvs too conservative. :P
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I could see an upper-end tropical storm out of this.

Maybe a minimal hurricane if it tries hard enough.

Member Since: July 6, 2010 Posts: 113 Comments: 32348
Trends in Nassau's weather over the past few days. Including Pressure which shows a decrease in pressure.

Link
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We should get a tropical storm out of 94L, assuming it forms. Looks like it will have enough warm-core characteristics to not be sub-tropical.

Member Since: July 15, 2006 Posts: 17 Comments: 10284
Quoting GTcooliebai:
Hey look the # 7



Models have been saying North Florida/ Southern Georgia every run.
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Quoting MississippiWx:


Of course! That's what we live for, right??
Absolutely! ;)
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting GTcooliebai:
I think our friend Jedkins is getting hammered I think he lives close to the St. Pete/Clearwater Airport.



Unfortunately that storm parted in 2 different directions, missing my house, however, I was at school and I was able to drive back in the thunderstorm on U.S. 19. Incredibly powerful storm, everyone was literally driving on idle speed and I could barely see the bumper of the driver in front of me, I was driving in that intensity for at least 10 to 20 minutes!

Wind gusts were easily 50 to 60 mph ad my car was rocking, I saw a few power flashes as well, small hail and a lots of intense white and purple lightning hits.

Crazy stuff! While I'm upset to find the strong thunderstorm parted before reaching my house, I'm glad I got to see some action while driving back. Classic afternoon sea breeze thunderstorms, I'm glad to see they are back :)


I did get a bit of heavy rain later on, a little over a quarter inch of rain, while its not much its better than being completely dry.

Man, that was a serious thunderstorm I drove through...
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411. LBAR
Anyone ever heard of a correlation between lady bug swarms and hurricanes? I was in Myrtle Beach earlier this month and the lady bugs were more than I've ever seen.
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Quoting Thrawst:


Quite the aggressive projection, Taz. :o


I am thinking 5-30 storms
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Hey look the # 7

Member Since: August 31, 2009 Posts: 0 Comments: 5628
Quoting MiamiHurricanes09:
Phil Ferro just posted on Facebook that 94L got bumped to 60%, so you know what that means, time to get back to blogging.

The satellite signature and cloud pattern associated with 94L has become increasingly organized throughout the past few hours and as a result it isn't surprising that the NHC has bumped its chances to develop into a cyclone. Surface observations across the Bahamas also indicate that pressures have been on a steady decrement and winds in the 30-35 knot range over the past 3-6 hours or so. The circulation is still a bit elongated from southwest to northeast and it'll take some time to consolidate into a well-defined vertically stacked LLC.

Something to note is that 94L has very good divergence/convergence. A sign that not only is it steadily organizing, but also still lowering atmospheric pressure.

Upper-level outflow is impressive in association with 94L towards the northern quadrant.


Looks like a significant event for North Florida/ Georgia.
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Quoting MiamiHurricanes09:
Possibly; I have my doubts though. ;)

Good to see you MissWX as well. Eager for them late nights until 7a.m tracking wimpy fish storms hahaa.


Of course! That's what we live for, right??
Member Since: July 15, 2006 Posts: 17 Comments: 10284
Quoting Tazmanian:
am thinking 15 too 24 name storms


Quite the aggressive projection, Taz. :o
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Oh? 94L up to 60% didn't see that coming...
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Quoting HurricaneDean07:

Here you are...
Alpha, Beta, Gamma, Delta, Epsilon, Zeta, Eta, Theta, Iota, Kappa, Lambda, Mu, Nu, Xi, Omicron, Pi, Rho, Sigma, Tau, Upsilon, Phi, Chi, Psi, Omega

It's impossible to run out of names for a storm season.
Seasonal Names - 21 storms
Greek Names - 24 storms
You would have to have a 45+ storm season to run out of names... THATS CRAZY
Member Since: October 3, 2010 Posts: 40 Comments: 4129
Quoting MississippiWx:


50-60kts of shear could have something to do with it. :-) Good to see you on, MH09.

Possibly; I have my doubts though. ;)

Good to see you MissWX as well. Eager for them late nights until 7a.m tracking wimpy fish storms hahaa.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
401. Stormchaser2007
1:23 AM GMT on May 25, 2012
This is Bud's nest, but the HWRF has not been run since yesterday for 94L.

We should have one tonight with the new upgrade implemented.

Member Since: June 9, 2007 Posts: 4 Comments: 15923
400. Gorty
1:23 AM GMT on May 25, 2012
Hmmm, I remember I had an early season heavy flurry in October then the winter was a non winter. Last October I got that crushing snow storm (it was really nasty here)and the winter was a non winter.

Not saying early start to the hurricane season will mean a non season, but we could see what an early start can mean.
Member Since: November 8, 2008 Posts: 12 Comments: 1058
399. MississippiWx
1:22 AM GMT on May 25, 2012
Quoting Gorty:


Such high shear yet it looks good.


The shape of the jet stream is actually helping to ventilate 94L somewhat. Shear is a good bit less closer to the center itself (only 20-30kts), so that is helping to sustain/slightly strengthen the system.
Member Since: July 15, 2006 Posts: 17 Comments: 10284
398. HurricaneDean07
1:22 AM GMT on May 25, 2012
Quoting GTcooliebai:
Well then you can always go into the Greek Alphabet :-P

Here you are...
Alpha, Beta, Gamma, Delta, Epsilon, Zeta, Eta, Theta, Iota, Kappa, Lambda, Mu, Nu, Xi, Omicron, Pi, Rho, Sigma, Tau, Upsilon, Phi, Chi, Psi, Omega
Member Since: October 3, 2010 Posts: 40 Comments: 4129
397. AllStar17
1:22 AM GMT on May 25, 2012
**THE LATEST**
(click to enlarge; all graphics can be further enlarged in Link window)


Member Since: June 29, 2009 Posts: 13 Comments: 5313
396. TropicalAnalystwx13
1:21 AM GMT on May 25, 2012
Quoting KoritheMan:
Cody, why aren't you doing more blogs? Don't let me outpace you.

This is all you're getting tonight. :P

Link
Member Since: July 6, 2010 Posts: 113 Comments: 32348
395. melwerle
1:20 AM GMT on May 25, 2012
Thanks, K. Still watch what is going on but since I'm not in the path ever, I just keep my mouth shut. Always thinking of everyone though that are in the areas.

In Sandy Eggo...we have the quakes but nothing else. We're heading to Cabo in a few days and not likely to hit any hurricanes there either. Always keeping and eye and sending out prayers.

Member Since: June 28, 2006 Posts: 12 Comments: 1837
394. Stormchaser2007
1:18 AM GMT on May 25, 2012
I could definitely see this season having 12-15 storms when everything is all said and done.

I doubt we'll see anything less than 11 due to these home-brews.
Member Since: June 9, 2007 Posts: 4 Comments: 15923
393. Gorty
1:18 AM GMT on May 25, 2012
Quoting MississippiWx:


50-60kts of shear could have something to do with it. :-) Good to see you on, MH09.



Such high shear yet it looks good.
Member Since: November 8, 2008 Posts: 12 Comments: 1058
392. trHUrrIXC5MMX
1:17 AM GMT on May 25, 2012
Quoting MAweatherboy1:

ATCF has said major hurricane all day, but recon said different, so as far as we know Bud is just shy of major hurricane strength.


you're wrong
Member Since: April 23, 2011 Posts: 104 Comments: 14873
391. MississippiWx
1:16 AM GMT on May 25, 2012
Quoting MiamiHurricanes09:
Phil Ferro just posted on Facebook that 94L got bumped to 60%, so you know what that means, time to get back to blogging.

The satellite signature and cloud pattern associated with 94L has become increasingly organized throughout the past few hours and as a result it isn't surprising that the NHC has bumped its chances to develop into a cyclone. Surface observations across the Bahamas also indicate that pressures have been on a steady decrement and winds in the 30-35 knot range over the past 3-6 hours or so. The circulation is still a bit elongated from southwest to northeast and it'll take some time to consolidate into a well-defined vertically stacked LLC.

Something to note is that 94L has very good divergence/convergence. A sign that not only is it steadily organizing, but also still lowering atmospheric pressure.

Upper-level outflow is impressive in association with 94L towards the northern quadrant.


50-60kts of shear could have something to do with it. :-) Good to see you on, MH09.

Member Since: July 15, 2006 Posts: 17 Comments: 10284
390. KoritheMan
1:15 AM GMT on May 25, 2012

Quoting melwerle:
Wow - early season this year.

Laughing at the computer models though - everyone is all over the place.

And to whomever was asking about "eating crow," give it a bit - you'll see many crow recipes throughout the season. (Kind of like eating your words.) There's Crow Cassoulet, Crow stew, Fried crow on waffles with gravy etc etc (depending on what part of the country you live).

Nice to see the activity - something to talk about but hoping that everyone stays safe.

Living in S. Cal now so we don't really talk about hurricanes here. When I was on the east coast, that was another story. Still follow and still lurk.

Have an awesome evening everyone.

Melissa
Good to see you again.
Member Since: March 7, 2007 Posts: 587 Comments: 20880
389. Tazmanian
1:14 AM GMT on May 25, 2012
Quoting MiamiHurricanes09:
I don't see 2012 receiving less than 12-14 cyclones.



or me i think we see a lot more then 12 too 14 name storms
Member Since: May 21, 2006 Posts: 5091 Comments: 115255
388. Walshy
1:13 AM GMT on May 25, 2012
That is a fairly large cloud canopy when compared to Alberto.
Member Since: May 17, 2009 Posts: 2 Comments: 904
387. melwerle
1:13 AM GMT on May 25, 2012
Wow - early season this year.

Laughing at the computer models though - everyone is all over the place.

And to whomever was asking about "eating crow," give it a bit - you'll see many crow recipes throughout the season. (Kind of like eating your words.) There's Crow Cassoulet, Crow stew, Fried crow on waffles with gravy etc etc (depending on what part of the country you live).

Nice to see the activity - something to talk about but hoping that everyone stays safe.

Living in S. Cal now so we don't really talk about hurricanes here. When I was on the east coast, that was another story. Still follow and still lurk.

Have an awesome evening everyone.

Melissa
Member Since: June 28, 2006 Posts: 12 Comments: 1837
386. Skyepony (Mod)
1:13 AM GMT on May 25, 2012
BUD
Member Since: August 10, 2005 Posts: 179 Comments: 38327
385. yqt1001
1:13 AM GMT on May 25, 2012
My turn then I guess; assuming that 94L develops into Beryl, which I don't have a strong opinion on as I find Bud & Eurovision taking my time this week.

May: Alberto, Beryl
June: Chris
July: Debby
August: Ernesto, Florence
September: Gordon, Helene, Isaac
October: Joyce, Kirk


Member Since: November 19, 2010 Posts: 1 Comments: 1286
384. MiamiHurricanes09
1:13 AM GMT on May 25, 2012
I don't see 2012 receiving less than 12-14 cyclones.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
383. allancalderini
1:13 AM GMT on May 25, 2012
Neutral years are really interesting Btw if Beryl develops of 94L we will be ahead of the 2005 hurricane season for like a month for this time of year.
Member Since: October 15, 2011 Posts: 0 Comments: 4410
382. JrWeathermanFL
1:12 AM GMT on May 25, 2012
May: Alberto, Beryl
June: Chris
July: Debby, Ernesto
August: Florence, Gordon, Helene
September: Isaac, Joyce, Kirk
October: Leslie, Michael
November: Nadine
Member Since: July 19, 2011 Posts: 12 Comments: 2459
381. HurricaneDean07
1:12 AM GMT on May 25, 2012
Quoting Hurricanes101:
One thing that may allow this season to squeeze out a few more storms than predicted is the higher chance of homegrown storms

Which means, As tropical waves chug along into the Caribbean, and Bahamas, they can boot up into storms, along with late-season cuasing trough splits.
Member Since: October 3, 2010 Posts: 40 Comments: 4129
380. Tazmanian
1:11 AM GMT on May 25, 2012
am thinking 15 too 24 name storms
Member Since: May 21, 2006 Posts: 5091 Comments: 115255
379. GTcooliebai
1:11 AM GMT on May 25, 2012
Quoting Tazmanian:

my turn


May Alberto,Beryl

june Chris Debby,Erenesto

july Florence,Gordon,Helene,Isaac,Joyce


Aug Kirk,Leslie,Michael,Nadine,Oscar

SEP Patty,Rafael,Sandy,Tony,Valerie

OCT William



out of names
Well then you can always go into the Greek Alphabet :-P
Member Since: August 31, 2009 Posts: 0 Comments: 5628

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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.

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