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 twhcracker:
i feel like i must be having a mild stroke or something cause i dont understand anything anybody is saying anymore. Like my god oil rigs are "known for cinnamon rolls." who on earth knows such things. and why would they pass out on them. and why would the cinnamon roll person be assigned to ... to what? To make sure the blow out preventer works? then we got your duckie and pony shower curtains, then someone might be stormtop or jfv then someone says nothing is gonna hit florida at all but maybe the panhandle, like we aint even fla like we are just the nations armpit or something, the fla stepchile. i am just confused


LOL...too many gherkins, I'm afraid
Member Since: August 2, 2006 Posts: 10 Comments: 9922


Looks like the circulation near 12N 96W is starting to win out. You can tell that from the precipitable water loop as well.
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Please, for the love of Pete, skip the politics right now. I'm no fan of Obama, but Bush had his particularly stupid moments. Clinton wasn't any better, but he could sell ice water to Eskimos. Congress makes the laws, Congress deregulated financial and energy industries, Congress is filled with lawyers who are bribed with millions of dollars of industry kickbacks and grift. All any President can do is rubber-stamp things which cross his desk and hope nothing serious blows up on his (or her, perhaps someday) watch.

I want to know whats happening in the Pacific and the Tropics (i.e. the Caribbean and GOM). I can go anywhere for politics as Obama has been busy making himself a good target. LOL
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It is a weather blog, but there's no real weather going on right now. Just a couple of pathetic swirls that some folks like to wishcast into Cat 5's hitting [insert closest metro area].
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Quoting Weather456:
If we take a look at the visible imagery of the WATL we see that 90E is being tugged NEward


I've been watching the same trend throughout the past couple hours. I found it very interesting that the latest GFDL and HWRF model runs take the system across the Yucatan and into the Southern Gulf of Mexico by mid next week. Definitely a change from the previous thinking, but I'm not totally buying it since I want to wait for some consistency and for better consolidation from the system itself.
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Whoa, I went to high school with Eric Blake. And the world just got even smaller...
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909. BVI
Quoting Weather456:
I'm gonna be getting some decent rains soon



you are, been pouring in Tortola for quite a few hours, just easing up now
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I thought this was a weather blog?

Any thoughts on what's going to happen in the Caribbean with the trough?
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Quoting Twinkster:


that comment about the current administration being socialist is totally uncalled for
The truth hurts, I know. Sorry.
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906. xcool
omg bp ,let talk about tropical weather,
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting RitaRefugee:
Reedzone...another conservative Christian here. And PROUD of it. With the doom and gloom of the growing death of a culture here in Louisiana, and the foreboding of a potentially record-setting hurriseason, and a socialist administration in the White House, all I can say is that I know what the future holds.


that comment about the current administration being socialist is totally uncalled for
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Absolutely, Reedzone. As Hannibal so famously said, "I love it when a plan comes together."
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I'm gonna be getting some decent rains soon

Member Since: July 24, 2005 Posts: 407 Comments: 19076
13.4N 94.2W

pretty clear where the center is setting up, nice spin there, good consolidation of clouds and it is moving north with the overall cloud pattern moving NE
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Quoting TampaSpin:
I wonder how much MUD they have on top to put down.......
they are bringing out 15000 more barrels
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Quoting amd:
children,

It is not Bush's fault, nor Obama fault, nor the toothfairy's fault, or anyone else that you want to sign blame on for the Oil Spill, except for one entity.

And, that entity is BP for being cheap with the materials needed to make sure that the oil well will work as planned at 5000 feet.


AMEN
Member Since: August 2, 2006 Posts: 10 Comments: 9922
Quoting weather42009:
The American people is to blame. All of you are guilty of buying oil from BP. Now there is a disaster, everybody's finding someone to blame except themselves.


Wait, so I buy gas at a BP outlet, and it is my fault that they displace to seawater with only one plug in place? I'm afraid I'm not prepared to accept responsibility for this disaster. Look elsewhere.
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i feel like i must be having a mild stroke or something cause i dont understand anything anybody is saying anymore. Like my god oil rigs are "known for cinnamon rolls." who on earth knows such things. and why would they pass out on them. and why would the cinnamon roll person be assigned to ... to what? To make sure the blow out preventer works? then we got your duckie and pony shower curtains, then someone might be stormtop or jfv then someone says nothing is gonna hit florida at all but maybe the panhandle, like we aint even fla like we are just the nations armpit or something, the fla stepchile. i am just confused
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456 do you have any updated thoughts on 90E?
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Quoting RitaRefugee:
Reedzone...another conservative Christian here. And PROUD of it. With the doom and gloom of the growing death of a culture here in Louisiana, and the foreboding of a potentially record-setting hurriseason, and a socialist administration in the White House, all I can say is that I know what the future holds.


As the joker would say "All part of the plan"
God Bless you brother :)
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Quoting Weather456:
If we take a look at the visible imagery of the WATL we see that 90E is being tugged NEward


Awfully elongated. It still looks like it is struggling to consolidate one main center.
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894. xcool
But I'm keeping an eye on it 90e
Member Since: September 26, 2009 Posts: 2 Comments: 15684
If we take a look at the visible imagery of the WATL we see that 90E is being tugged NEward
Member Since: July 24, 2005 Posts: 407 Comments: 19076
I know what the future holds for me


DINNER!!
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Quoting reedzone:
Sorry, I'm one of the few conservative Christians in here, I'm done talking politics lol.. How are things with 90E?


Hey reed, looks like the convection in 90E is consolidating more toward the center.
Member Since: May 26, 2010 Posts: 0 Comments: 804
Can we get back to weather please. and RIP 90L it was a good ride.
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I wonder how much MUD they have on top to put down.......
Member Since: September 2, 2007 Posts: 179 Comments: 20448
90E is now moving North
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If we take a look at the visible imagery of the WATL we see that 90E is being tugged NEward

Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting CycloneOz:


Oh...we had an oil rig disaster under the last president. Oh...I forgot about that one.

Please refresh my memory...I cannot remember that oil disaster that TOOK OUT AN ENTIRE BODY OF WATER!!! :p


I won't argue the criminalty of the Cheney adminstration in this forum. Suffice it to say that the realxation of regulations didn't start with this administration, nor did it start with the last. Blaming this administration for the de-regulation wave that started twenty years ago is like blaming your cancer on this morning's breakfast...it may comfort you, but that doesn't make it any more true
Member Since: August 2, 2006 Posts: 10 Comments: 9922
884. xcool
Convection starting 90e
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting amd:
children,

It is not Bush's fault, nor Obama fault, nor the toothfairy's fault, or anyone else that you want to sign blame on for the Oil Spill, except for one entity.

And, that entity is BP for being cheap with the materials needed to make sure that the oil well will work as planned at 5000 feet.


A voice of reason
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Yeesh. I think I'll go hang out the climate change blog where clear heads prevail and politics never intrude...
(lol)
Member Since: August 16, 2007 Posts: 6 Comments: 12463
Take the politics to another blog or the yahoo news comment sections.. not here.
Member Since: July 8, 2005 Posts: 259 Comments: 24574
880. amd
children,

It is not Bush's fault, nor Obama fault, nor the toothfairy's fault, or anyone else that you want to sign blame on for the Oil Spill, except for one entity.

And, that entity is BP for being cheap with the materials needed to make sure that the oil well will work as planned at 5000 feet.
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Just read Jeff Masters' blog, quite alarming.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
I took a peek at some of the past records from periods when the Pacific Decadal Oscillation was in its "cool phase" and the Sun was at or near a Solar Minimum. I was looking for trends.

I didn't see much in the data that would help with forecasting; 1976, 77, and 78 were the last three years of the last cool PDO phase. If anyone has more info on those years perhaps it will help. Seemed like they were relatively inactive though...

I live in the southeastern California desert, and can definitely say that the cool PDO phase has made a HUGE difference in our weather in the last 6 months. It seems to be steering more "Alaskan lows" down into southern California which disrupts the seasonal high pressure which builds over the "Four Courners" area (where CA, NV, UT, and AZ all meet). When this high can't build for weeks at a time, it appears to keep our daytime highs supressed, and reinforces the nighttime low tems. We saw mid-40s this past weekend when the last low swept over. I was driving to LA mid-morning on Saturday and drove through sizeable soft hail in Banning, CA. There's still snow on the mountain top over Palm Springs, CA; it's worth noting.

I'm just saying whatever's happening in the Pacific is STRONG. It's like nothing I've seen in 15 years of desert living!
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Quoting Skyepony:
Pretty long lived for an invest...loved the 3 swirls dancing round each other..never hurt noone..wish the whole season could be like 90L..


yea Skye 90L was a pretty interesting Invest to track
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I'm gonna go find me an actual weatherblog myself. If I wanted to read this kind of anti-obama hysteria I could visit red state.

Later.
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875. xcool
come on now noomore about oil.toomuch.
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting Floodman:


I will repeat, where were these safegaurds under the last president? Ask anyone on a rig right now that worked them then: they weren't there...plenty of blame to go around and it extends into the past...


LMAO....WHERE WAS THE CHANGE SOME VOTED FOR! He had an opportuinty to change anything he wanted but, choose to issue a Permitt for something that was crossing into another league. Why didn't he "OBAMA" make a change that you voted for........BS
Member Since: September 2, 2007 Posts: 179 Comments: 20448
873. Skyepony (Mod)
Pretty long lived for an invest...loved the 3 swirls dancing round each other..never hurt noone..wish the whole season could be like 90L..
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Worst storm season ever! 7.4 earthquake! Oil still flowing in the GOM!!! All today!! Yet nothing but politics???
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871. xcool
wunder now politics blog..
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Sorry, I'm one of the few conservative Christians in here, I'm done talking politics lol.. How are things with 90E?
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re: 861

I think you should read back a bit further in the blog - especially the junk being spouted while I was still at work.
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Quoting TampaSpin:


There you GO! OBAMA APPROVED THE PERMITT TO DRILL THIS DISASTER and pushed through all kinds of red tape to get it approved without going through all the proper channels.....THESE ARE THE FACTS! CONTINUE PLEASE!

U.S. Said to Allow Drilling Without Needed Permits
By IAN URBINA
Published: May 13, 2010





If this happened during bush's presidency it would be only BP's fault correct?

When the permit was issued for this rig in 2009 the regulations were exactly the same as those in the bush era. When obama came in too office he had plenty more to worry about such as a horrible recession caused by lack of regulation in the financial sector(thank you reagan) be realistic this was much more important than oil corporation regulation that seemed to work during the bush administration.

The goal of the president is to not fix everything just fix the problems. When obama came in to office the regulation of oil industries seemed to work so why concentrate on fixing something that didn't seem broken.

You have to be realistic. I didn't want to make this a political argument I just wanted you guys to give respect to the President that he rightly deserves
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Quoting Tropicsweatherpr:
Its over for 90L.

NHC_ATCF
invest_DEACTIVATE_al902010.ren
FSTDA
R
U
040
010
0000
201005272046
NONE
NOTIFY=ATRP
END


RIP 90L
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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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