NOAA predicts a near-normal Atlantic hurricane season

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

Share this Blog
33
+

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

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 479 - 429

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16Blog Index

479. MahFL
I think I see the shear relaxing a touch over 94L, the cold ir clouds are moving west a touch.
Member Since: Posts: Comments:



Warned Severe thunderstorm from earlier before I drove into it :)
Member Since: Posts: Comments:
Quoting washingtonian115:
If Beryl forms I can only imagine the Doc's blog title when that happens..."UNPRECEDENTED 2ND STORM FORMS BEFORE JUNE".Lol.


The only ones I could find.

May 15-20,1887



May 17-21, 1887
Member Since: Posts: Comments:
Quoting sunlinepr:


Does that say 115kt/947 MB?
Member Since: Posts: Comments:
Member Since: Posts: Comments:
SPECIAL TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
840 PM EDT THU MAY 24 2012

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

1. SATELLITE IMAGES INDICATE THAT THE CLOUD PATTERN ASSOCIATED WITH THE
BROAD AREA OF LOW PRESSURE...LOCATED BETWEEN THE NORTHWESTERN
BAHAMAS AND SOUTHEASTERN FLORIDA...HAS GRADUALLY BECOME BETTER
ORGANIZED THIS AFTERNOON AND EVENING. ENVIRONMENTAL CONDITIONS ARE
EXPECTED TO BECOME MORE CONDUCIVE FOR THE FORMATION OF A
SUBTROPICAL OR TROPICAL CYCLONE BY SATURDAY OVER THE WESTERN
ATLANTIC OCEAN OFF OF THE SOUTHEASTERN UNITED STATES.
THIS SYSTEM
HAS A HIGH CHANCE...60 PERCENT...OF BECOMING A TROPICAL OR
SUBTROPICAL CYCLONE DURING THE NEXT 48 HOURS AS IT MOVES
NORTHEASTWARD AT 10 TO 15 MPH.

THIS SYSTEM IS PRODUCING SUSTAINED WINDS OF AROUND 30 MPH WITH WIND
GUSTS OF TROPICAL STORM FORCE...MAINLY TO THE EAST OF THE CENTER
OVER WATER. REGARDLESS OF ANY DEVELOPMENT...LOCALLY HEAVY
RAINFALL...FLOODING...AND GUSTY WINDS ARE STILL POSSIBLE OVER
PORTIONS OF THE NORTHWESTERN AND CENTRAL BAHAMAS...AS WELL AS
CENTRAL CUBA TONIGHT AND TOMORROW. INTERESTS ALONG SOUTHEASTERN
UNITED STATES COAST SHOULD CLOSELY MONITOR THE PROGRESS OF THIS
SYSTEM OVER THE MEMORIAL DAY WEEKEND. ANOTHER SPECIAL TROPICAL
WEATHER OUTLOOK FOR THIS SYSTEM WILL BE ISSUED ON FRIDAY. FOR
ADDITIONAL INFORMATION ON THIS SYSTEM...PLEASE SEE HIGH SEAS
FORECASTS ISSUED BY THE NATIONAL WEATHER SERVICE...AND PRODUCTS
FROM YOUR LOCAL WEATHER OFFICE.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

3. &&

4. HIGH SEAS FORECASTS ISSUED BY THE NATIONAL WEATHER SERVICE CAN BE
FOUND UNDER AWIPS HEADER NFDHSFAT1 AND WMO HEADER FZNT01 KWBC.

$$
FORECASTER KIMBERLAIN/STEWART
Member Since: July 6, 2010 Posts: 113 Comments: 32285
A lot of updates to models going on. You can add the RAP into the mix of updated models to go along with the new GFS/HWRF. The RAP (rapid updating model) replaces the RUC model for short term weather predictions. The RAP is now in use on the NCEP model page.
Member Since: Posts: Comments:
Member Since: July 6, 2010 Posts: 113 Comments: 32285
Quoting MississippiWx:


True, but you can hardly ever count on the NAM initializing tropical low pressure areas with the correct pressure.


So what does the new run show?
Member Since: March 22, 2012 Posts: 0 Comments: 723
Quoting wpb:
gfs and hmrf are getting there upgrade anybody know when???

GFS had its update two days ago, and HWRF had its today.
Member Since: July 6, 2010 Posts: 113 Comments: 32285
Not sure i see a Named Storm coming in the Atlantic from 94L...there are a lot of things working against it....DRY AIR and HIGH SHEAR with the models that i have looked at only showing the Shear relaxing to around 30kts....gonna be tough to develop in that Shear. We shall see tho.
Member Since: Posts: Comments:
468. wpb
gfs and hmrf are getting there upgrade anybody know when???
Member Since: Posts: Comments:
467. Skyepony (Mod)
Some of the Radiation readings are up a little in the NE this evening.

Member Since: August 10, 2005 Posts: 175 Comments: 38210
18Z Nogaps

Member Since: Posts: Comments:
Quoting TropicalAnalystwx13:

Initialized in the correct spot, but too weak.


True, but you can hardly ever count on the NAM initializing tropical low pressure areas with the correct pressure.
Member Since: Posts: Comments:
Quoting MississippiWx:
I know everyone has been itching for the arrival of the 0z NAM, but it has started its run if you cared to know. Seems like it initialized in the correct location. Here is 6hrs out:


Initialized in the correct spot, but too weak.
Member Since: July 6, 2010 Posts: 113 Comments: 32285
Quoting Patrap:


Note latest Stats on 94L:
45 Mph winds
1004 MB
Member Since: October 3, 2010 Posts: 40 Comments: 4129
Quoting MississippiWx:
I know everyone has been itching for the arrival of the 0z NAM, but it has started its run if you cared to know. Seems like it initialized in the correct location. Here is 6hrs out:



Thanks for the update
Member Since: March 22, 2012 Posts: 0 Comments: 723
Quoting TropicalAnalystwx13:

If Bud becomes a major hurricane tonight, it will be the earliest forming Eastern Pacific major hurricane on record.

To top it all off, we ended last year with Kenneth...it was the latest forming Eastern Pacific major hurricane on record.
this year really want to break records in two basins.
Member Since: October 15, 2011 Posts: 0 Comments: 4401
It all depends of the weather patterns in the area to where any contamination will spread, if any......




Local TV: Nuclear sub fire very difficult to fight Special operation team arriving on scene Heat creating significant amount of steam Burning for over 7 hours

Published: May 24th, 2012 at 1:16 am ET

See first report here: Nuclear sub burning 50 miles from Boston -- "It doesn t smell like a regular fire" -- Black smoke continues billowing (PHOTOS)
Update: 4-alarm fire less than 300 feet away from nuclear reactor -- Steam continues to be emitted from burning sub -- New aerial footage (VIDEOS)
Update: Fire extinguished, Commander reveals nuclear fuel on board burned sub -- Local News: He 'could not say how much'

Fire on nuke-powered sub at Portsmouth Naval Shipyard hurts 6 WMUR 12:59 AM EDT May 24, 2012


Fire crews responded Wednesday to the USS Miami SSN 755 at the Portsmouth Naval Shipyard around 5:41 p.m.

[...]

Around 11:45 p.m. on Wednesday, Fuller said the fire was not out, but conditions were improving. He said heat from the fire was still creating a significant amount of steam.
Member Since: Posts: Comments:
Quoting tampahurricane:
St. Petersburg got slammed, went out chasing water in business on US19 got between 3-5 inches within less than an hour. There was a 100% chance of hail, i witnessed a little hail on the road but i mostly missed the hail core. Starting to slowdown now.




Looks like you drove through the same thunderstorm I did on the way back from school, as I was heading into it, I knew it would be strong, but it ended up being much worse than I was anticipating hahaha. My gosh, it brought back some memories. Believe it or not I've actually drove through even worse than that lol, but that had my heart pumping with excitement though!
Member Since: Posts: Comments:
I know everyone has been itching for the arrival of the 0z NAM, but it has started its run if you cared to know. Seems like it initialized in the correct location. Here is 6hrs out:

Member Since: Posts: Comments:
457. Skyepony (Mod)
Quoting 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.


Ladybug swarms bring good luck. They are usually followed by fair weather.
Member Since: August 10, 2005 Posts: 175 Comments: 38210
Member Since: Posts: Comments:
Just remember not to get so fixated on the center of 94 or where the center makes landfall, if that happens. The moisture is going to be well displaced from the center and areas north and east of the storm will see the bulk of any wind and rain. While I do believe it will eventually become fully warm core, it's still going to be a "lopsided" storm as dry air remains be an inhibiting factor on the west side.
Member Since: Posts: Comments:
Good night Bud.

Member Since: July 6, 2010 Posts: 113 Comments: 32285
Member Since: Posts: Comments:
For some reason, I am reminded of 90L of 2009. Does anyone else remember that?
Member Since: December 21, 2007 Posts: 13 Comments: 3046
Quoting cg2916:


Impressive! Does the yellow denote TS force winds?


35 knots in the Hatched areas I do believe
Member Since: Posts: Comments:
Quoting WxGeekVA:
Best looking hurricane in months goes to Bud:


If Bud becomes a major hurricane tonight, it will be the earliest forming Eastern Pacific major hurricane on record.

To top it all off, we ended last year with Kenneth...it was the latest forming Eastern Pacific major hurricane on record.
Member Since: July 6, 2010 Posts: 113 Comments: 32285
Quoting washingtonian115:
If Beryl forms I can only imagine the Doc's blog title when that happens..."UNPRECEDENTED 2ND STORM FORMS BEFORE JUNE".Lol.


+ 100000

This made me chuckle
Member Since: March 22, 2012 Posts: 0 Comments: 723
Member Since: Posts: Comments:
Quoting WxGeekVA:


He's got green on da Funktop too...


That eyewall!
Member Since: December 21, 2007 Posts: 13 Comments: 3046
Quoting Patrap:



wow that has 40kt and 1003mb for 94L
Member Since: May 21, 2006 Posts: 5091 Comments: 115244
Quoting 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.


Animals can tell a lot , they have an uncanny sense about the weather plus other things, sounds much like the crabs on Cayman Brac, ie: when the Tsunami hit Indonesia in 12/2004, the Elephants headed for higher grounds and some people went running towards the sea, maybe us humans just don't have that extra sense that the animals are blessed with.
Member Since: Posts: Comments:
Quoting Patrap:


Impressive! Does the yellow denote TS force winds?
Member Since: December 21, 2007 Posts: 13 Comments: 3046


He's got green on da Funktop too...
Member Since: Posts: Comments:
wind shear will be droping
Member Since: May 21, 2006 Posts: 5091 Comments: 115244
Quoting MississippiWx:


That seems like the most favored track at this point. The ridge that is supposed to build to the north should be strong enough to steer it away from SC/NC and back towards FL/GA. I'm selfishly hoping it can take the NAM track and come to me in MS via the Northern Gulf Coast. We need the rain...trying to fill up a new lake!! :-)


On the Bright side, It looks like after it will make a landfall there, it will head NE over South Carolina, North Carolina, and parts of virgina
Member Since: March 22, 2012 Posts: 0 Comments: 723
Member Since: Posts: Comments:
Quoting Thundercloud01221991:


Fine I will increase my predictions....

6-31 storms


Good!! that's more like it.
Member Since: Posts: Comments:
With 50-60 knots of shear, dry air, barely warm enough waters, and DMIN, we still get a pretty strong 94L. Wow. Can't wait to wake up.

Good to see you, MiamiHurricanes09!
Member Since: December 21, 2007 Posts: 13 Comments: 3046
If Beryl forms I can only imagine the Doc's blog title when that happens..."UNPRECEDENTED 2ND STORM FORMS BEFORE JUNE".Lol.
Member Since: Posts: Comments:
Best looking hurricane in months goes to Bud:

Member Since: Posts: Comments:
00z Early Cycle NHC model tracks
Invest94
Statistical/Simple Models (CLIPER,BAMs,LBAR,other Statistical Models)





Dynamic Models (More sophisticated models)



Early Model Wind Forecasts

Member Since: Posts: Comments:
Quoting BrickellBreeze:


Do you agree with my statement that a track towards North Florida, Southern Georgia seems the most likely?


That seems like the most favored track at this point. The ridge that is supposed to build to the north should be strong enough to steer it away from SC/NC and back towards FL/GA. I'm selfishly hoping it can take the NAM track and come to me in MS via the Northern Gulf Coast. We need the rain...trying to fill up a new lake!! :-)
Member Since: Posts: Comments:
Quoting Thundercloud01221991:


Fine I will increase my predictions....

6-31 storms



LOL
Member Since: May 21, 2006 Posts: 5091 Comments: 115244
432. Skyepony (Mod)
AEMI & AVNI initialized a little better but none really have a handle on 94L yet.
Member Since: August 10, 2005 Posts: 175 Comments: 38210
Member Since: Posts: Comments:
Quoting Skyepony:


Someone smashed a spider on the guidance page again. Darn...That always ruins our projections...
Member Since: Posts: Comments:
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?
Member Since: March 22, 2012 Posts: 0 Comments: 723

Viewing: 479 - 429

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16Blog Index

Top of Page

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.