NOAA's forecast: a very active, possibly hyperactive Atlantic hurricane season

By: Dr. Jeff Masters , 3:29 PM GMT on May 27, 2010

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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

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Quoting Levi32:


The gulf is beginning to get troublingly warm.

La Nina showing up too.

Kinda scary how fast the GOMEX is warming. You can really see how much the Niña 1+2 region has warmed.
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1365. pottery
Quoting pottery:

How the Devil do you Know that.
This is the problem with etc etc etc...

I was just staying with the Mood here, Gro!
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Quoting Patrap:
I sense a group hug coming on..
Come on,group Hug..everyone in tight

Dats it..((((((((((((wuba clan)))))))))))))


LOL Pat
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1363. Patrap
I sense a group hug coming on..
Come on,group Hug..everyone in tight

Dats it..((((((((((((wuba clan)))))))))))))
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1362. pottery
Quoting FIU2010:
ignore the haters, Weather456. You are porb. the only blogger on here that actually has a B.A Degree in meteorology. Be proud of your exceptional intellegence regarding the field of tropical meteorology, my Carribean friend. You poses a skill that many on here wish they actually had, with perhaps the exception of a handful of bloggers, and obviously speaking here, they know who they are, :).

I agree with that, completely.
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Quoting Levi32:


The gulf is beginning to get troublingly warm.

La Nina showing up too.



Warmer than the models were forecasting.
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Quoting Grothar:


Hey, Chicklit, I don't want to be disagreeab le, but only about 50% of the moon is illuminated. I believe the other side is totally dark.


And 50% is always illuminated. :)
Member Since: August 22, 2008 Posts: 12 Comments: 6010
Quoting Weather456:
DDR,

no its not raining here as yet, but the radar shows plenty of the wet stuff to come'

Pretty bad here in Miami too.

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1358. FIU2010
ignore the haters, Weather456. You are porb. the only blogger on here that actually has a B.A Degree in meteorology. Be proud of your exceptional intellegence regarding the field of tropical meteorology, my Carribean friend. You poses a skill that many on here wish they actually had, with perhaps the exception of a handful of bloggers, and obviously speaking here, they know who they are, :).
1357. pottery
Quoting Grothar:


Hey, Chicklit, I don't want to be disagreeab le, but only about 50% of the moon is illuminated. I believe the other side is totally dark.

How the Devil do you Know that.
This is the problem with etc etc etc...
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Forecast For The 2010 Hurricane Season

The National Hurricane Center has released its forecast for the upcoming tropical season this morning and they say it could be a busy year.

If the forecast holds true, it could be one of the busiest years on record.

Forecasts released earlier this spring showed a potential for a very active 2010 hurricane season.

Speaking with experts today, they say all the ingredients are there for a very busy few months ahead.

The past few hurricane seasons in Florida have come and gone with little activity.

But this year could be much different.

"The main thing about the outlook if that there are several factors that are indicators of a very active season." Paul Duval, Tallahassee NWS Meteorologist.

And active could be an understatement.
The forecast from NOAA and the Hurricane Center call for 14 to 23 named storms, 8 to 14 hurricanes, and 3 to 7 major hurricanes, a well above average year.

Forecasters say sea surface temperatures are running well above average so far this year, and the main player in tropical forecasting, El Nino, has been replaced by a neutral pattern.

Experts say with these pieces in place, this outlook isn't a shock.

"There's absolutely no surprise that whenever it is neutral or La Nina that we'll definitely have a lot more hurricanes." says Professor Of Meteorology James O'Brien.

The numbers are large, but the intensity of the hurricanes is still up in the air.

Forecasters say it's hard to determine how strong a storm will be, but one factor in the Gulf of Mexico, that has been in the news lately, is receiving a lot of attention.

"I don't think we're really saying the loop current has an impact on how active the year will be, but rather any potential strengthening or weakening in the eddy's absence and the storms final days as it approaches land in the Gulf of Mexico." says COAPS Research Scientist, Steven Morey.

Officials at the National Weather Service office in Tallahassee say this forecast should serve as a reminder for people around the area to prepare.

"Regardless of what the seasonal outlook is, don't change your preparation any. You should be as prepared for this season as you would for previous season, because it only takes one."
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DDR,

no its not raining here as yet, but the radar shows plenty of the wet stuff to come'

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1354. Grothar
Quoting Chicklit:


Full Moon, 100% of the Moon is Illuminated



Hey, Chicklit, I don't want to be disagreeab le, but only about 50% of the moon is illuminated. I believe the other side is totally dark.
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1353. Levi32
Quoting Patrap:


The gulf is beginning to get troublingly warm.

La Nina showing up too.

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1352. Dakster
Quoting Drakoen:


Me too.


Pass the salt... ohh and a napkin...

What is this place going to be like when a real storm forms and threatens land...

To be fair, it isn't like the NHC forecasters are always 100% correct either. I don't think any of the featured bloggers were way off base either.
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Grothar, I'll have you know that I'm not...okay, well maybe I'm a little feisty
Member Since: August 2, 2006 Posts: 10 Comments: 9922
1350. gator23
Quoting Floodman:


Now I will say this...our newly amnestied friend shows all gray...LOL


lol saw that
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1349. Patrap
Dr Masters is my pick.

Im a observer,..no met training,but a lotta heart.



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1347. gator23
Quoting FIU2010:
No, I am not from hialeah, brickell boy.


sure ya are.
Member Since: August 26, 2008 Posts: 0 Comments: 2182
Quoting gator23:


where did u place?


Now I will say this...our newly amnestied friend shows all gray...LOL
Member Since: August 2, 2006 Posts: 10 Comments: 9922
1345. EricSFL
Quoting FIU2010:
No, I am not from hialeah, brickell boy.


I just assumed you were from the words you use to offend people in Spanish. Like what you said to Acemett a couple days ago.
Member Since: May 26, 2010 Posts: 0 Comments: 804
1344. xcool
i'm from space...
Member Since: September 26, 2009 Posts: 2 Comments: 15684
90E stays same in strength:

EP, 90, 2010052800, , BEST, 0, 130N, 945W, 25, 1006, LO, 34, NEQ, 0, 0, 0, 0, 1010, 200, 60, 0, 0, E, 0, , 0, 0, INVEST, D,
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Quoting Weather456:


A word of advice, humility is a man's best friend.


Ahh that's true..
Member Since: July 1, 2008 Posts: 13 Comments: 7423
1341. pottery
OK, here is my Poll.

Who is the best forecaster on the blog?"

and yes, you can vote for yourself.
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my god, what is wrong with almost everyone today? is it a full moon?
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Quoting Grothar:


Oh, Yes we DO!!!!

(Hey, Dan!) Feisty little group tonight.


LOL Feisty - being nice tonight are you? :) I am noticing a trend on which ones have the biggest chips on their shoulders. One or two in particular. Ike is popping so much popcorn I can smell it from here. LOL
Member Since: August 22, 2008 Posts: 12 Comments: 6010
1338. Grothar
Quoting reedzone:
Darn guys, I'll say i again, it's an ARGUABLE matter on if 90L was Subtropical or Non-Tropical..There is evidence that 90L was Subtropical, and same evidence that it never transitoned.


Let it go, Reed. In a week, no one will even remember we had a 90L. Save your energy for 91L.
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1337. gator23
Quoting Floodman:


Wow, I was in a race? No, logged out of my account I have no controls here, so I can't filter for "best"


I just realized I could check for you. You are a "show good"
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1336. Patrap
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Quoting CaicosRetiredSailor:





Full Moon, 100% of the Moon is Illuminated

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1334. FIU2010
No, I am not from hialeah, brickell boy.
JVF with pimples my God whats he going to have to worry about now.
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1331. gator23
Quoting FIU2010:


heaven forbid, what's wrong with you, viejo!


oye take that stuff to Westland Mall
Member Since: August 26, 2008 Posts: 0 Comments: 2182
Quoting reedzone:
Darn guys, I'll say i again, it's an ARGUABLE matter on if 90L was Subtropical or Non-Tropical..There is evidence that 90L was Subtropical, and same evidence that it never transitoned.


A word of advice, humility is a man's best friend.
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1329. FIU2010
its pouring over here right now
Quoting gator23:


where did u place?


Wow, I was in a race? No, logged out of my account I have no controls here, so I can't filter for "best"
Member Since: August 2, 2006 Posts: 10 Comments: 9922
Quoting weather42009:


So what? Maybe W456 does not care for what you have to say. You are not all that ya know.


Your just causing trouble arent you?

You'll be gone soon enough.

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Quoting Hurricanes101:
Wow now we have arguing about whether people were arguing

*gets more popcorn*


With my comment, we will be having a meta-meta-meta-meta discussion of hurricanes. That's a lot.
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Darn guys, I'll say i again, it's an ARGUABLE matter on if 90L was Subtropical or Non-Tropical..There is evidence that 90L was Subtropical, and same evidence that it never transitoned.
Member Since: July 1, 2008 Posts: 13 Comments: 7423
1324. FIU2010
Quoting Patrap:
If a Cat 5.5 Hypercane sucks up a Bunch of BP poo crude,,and throws it over Miami,,I guess the Oil could cause a massive Teen Acne Crisis.

Add some Clearasil to the Prep kit just in case.


heaven forbid, what's wrong with you, viejo!
Quoting Floodman:


No, he meant "acne"...LOL


LOL!
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1322. Grothar
Quoting PcolaDan:


We do NOT. :)


Oh, Yes we DO!!!!

(Hey, Dan!) Feisty little group tonight.
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Thanks for those models Pat. Looks like they are more in agreement on a Neasterly course than earlier today.

"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." JM PhD
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1320. pottery
Quoting kmanislander:


No thread my friend, just chest thumping

Ah!
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Quoting pottery:
Reading back a few pages, I realise that you all are WAY ahead of me.
By a least 6 drinks... cant follow the thread at all....



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1318. gator23
Quoting Patrap:
If a Cat 5.5 Hypercane sucks up a Bunch of BP poo crude,,and throws it over Miami,,I guess the Oil could cause a massive Teen Acne Crisis.

Add some Clearasil to the Prep kit just in case.


or just spray some dispersant on em
Member Since: August 26, 2008 Posts: 0 Comments: 2182
1317. IKE
A lot of jabs being thrown around here this evening.

***breaks floss pick....reaches for another one***

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Quoting NttyGrtty:
As an old guy, I'd like to point out that you young guys are starting to bicker like old guys...


Okay, now I don't care who you are, THAT'S funny!
Member Since: August 2, 2006 Posts: 10 Comments: 9922

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About

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