CSU predicts highly active hurricane season; Cyclone Phet approaching Oman

By: Dr. Jeff Masters , 14:00 GMT le 03 juin 2010

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A very active Atlantic hurricane season is on tap for 2010, according to the seasonal hurricane forecast issued June 2 by Dr. Phil Klotzbach and Dr. Bill Gray of Colorado State University (CSU). The CSU team is calling for 18 named storms, 10 hurricanes, and 5 intense hurricanes, and an Accumulated Cyclone Energy (ACE) 185% of average. Between 1950 - 2000, the average season had 10 named storms, 6 hurricanes, and 2 intense hurricanes. But since 1995, the beginning of an active hurricane period in the Atlantic, we've averaged 14 named storms, 8 hurricanes, and 4 intense hurricanes per year. The new forecast is a step up from their April forecast, which called for 15 named storms, 8 hurricanes, and 4 intense hurricanes. The new forecast calls for a much above-average chance of a major hurricane hitting the U.S., both along the East Coast (51% chance, 31% chance is average) and the Gulf Coast (50% chance, 30% chance is average). The risk of a major hurricane in the Caribbean is also high, at 65% (42% is average.) This is the most aggressive early June forecast ever issued by the CSU group; the previous most aggressive such forecasts were for the 2006 and 2007 seasons, when the CSU team predicted 17 named storms, 9 hurricanes, and 5 intense hurricanes. Both of these forecasts did poorly, particularly the 2006 forecast, as only 10 named storms, 5 hurricanes, and 2 intense hurricanes were observed.

The forecasters cited four main reasons for an active season:

1) Weak La Niña conditions should develop by the most active portion of this year's hurricane season (August-October). The expected trend towards weak La Niña conditions should lead to reduced levels of vertical wind shear compared with what was witnessed in 2009.

2) Current SST anomalies are running at near-record warm levels. These very warm waters are associated with dynamic and thermodynamic factors that are very conducive for an active Atlantic hurricane season.

3) A weaker-than-normal Azores High prevailed during April-May. Weaker high pressure typically results in weaker trade winds that are commonly associated with more active hurricane seasons.

4) We are in the midst of a multi-decadal era of major hurricane activity, which began in 1995. Major hurricanes cause 80-85 percent of normalized hurricane damage.

Analogue years
The CSU team picked four previous years when atmospheric and oceanic conditions were similar to what we are seeing this year: weak El Niño to neutral conditions, well above-average tropical Atlantic SSTs, and above-average far North Atlantic SSTs during April - May. Those four years were 2005, the worst hurricane season of all time; 1969, the 3rd worst hurricane season of all time, featuring Category 5 Hurricane Camille which hit Mississippi; 1966, a relatively average year that featured Category 4 Inez that killed 1,000 people in Haiti; and 1958, a severe season with 5 major hurricanes. The mean activity for these five years was 17 named storms, 10 hurricanes, and 5 intense hurricanes, almost the same as the 2009 CSU forecast.

How accurate are the June forecasts?
The June forecasts by the CSU team over the past 12 years have had a skill 19% - 30% higher than a "no-skill" climatology forecast for number of named storms, number of hurricanes, and the ACE index (Figure 1). This is a decent amount of skill for a seasonal forecast, and these June forecasts can be useful to businesses such as the insurance industry and oil and gas industry that need to make bets on how active the coming hurricane season will be. Unfortunately, the CSU June 1 forecasts do poorly at forecasting the number of major hurricanes (only 3% skill), and major hurricanes are what do 80 - 85% of all hurricane damage (normalized to current population and wealth levels.) This year's June forecast uses the same formula as the past two years, which did quite well predicting the 2008 hurricane season (prediction: 15 named storms, 8 hurricanes, 4 intense hurricanes; observed: 16 named storms, 8 hurricanes, 5 intense hurricanes) and 2009 hurricane season (prediction: 11 named storms, 5 hurricanes, 2 intense hurricanes; observed: 9 named storms, 3 hurricanes, 2 intense hurricanes.) An Excel spreadsheet of their forecast skill (expressed as a mathematical correlation coefficient) show values from 0.44 to 0.58 for their June forecasts, which is respectable.


Figure 1. 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. The British firm Tropical Storm Risk (TSR) will issue their outlook for the 2010 Atlantic hurricane season on June 4. Image credit: Verification of 12 years of NOAA seasonal hurricane forecasts, National Hurricane Center.

NOAA's 2010 hurricane season forecast
NOAA issued their forecast for the upcoming Atlantic hurricane season last week. As I discussed in my post on their forecast, NOAA is calling for 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."


Figure 2. Visible satellite image of Tropical Cyclone Phet on Thursday, June 3, 2010.

Tropical Cyclone Phet the 2nd strongest Arabian Sea storm on record
Record heat over southern Asia in May has helped heat up the Arabian Sea to 2°C above normal, and the exceptionally warm SSTs helped fuel Tropical Cyclone Phet into the second strongest tropical cyclone ever recorded in the Arabian Sea. Phet peaked at Category 4 strength with 145 mph winds yesterday, and has weakened slightly to 135 mph winds this morning. Only Category 5 Cyclone Gonu of 2007, which devastated Oman, was a stronger Arabian Sea cyclone.

Phet is over very warm waters of 30 - 31°C, and is under moderate wind shear of 10 - 20 knots. However, the storm is wrapping in dry air from the Arabian Peninsula, which has caused weakening. Visible satellite imagery from this morning (Figure 2) shows that the heavy thunderstorms on the north side of Phet have been eroded away by dry air. Phet is a small storm, and could fall apart fairly quickly if dry air can penetrate into its core. This should happen later today, since wind shear is on the increase, and the shearing winds should be able to disrupt the circulation enough that dry air can force its way into Phet's eyewall. Phet is fairly small, will miss the most heavily populated areas of Oman, and will likely undergo significant weakening before landfall, so the storm is unlikely to cause the kind of catastrophic flooding that Category 5 Cyclone Gonu of 2007 brought to Oman. Gonu killed 50 people and did $4.2 billion in damage. Phet's heaviest rains will be confined to a relatively sparsely populated region of Oman's coast. Rainfall amounts in excess of 6 inches in 18 hours (Figure 3) can be expected along Oman's coast today, which will likely cause extreme flooding.

After Phet's encounter with Oman, the storm will probably be at tropical storm strength when it makes its second landfall in Pakistan. Heavy rains from Phet will be the major danger for Pakistan, and serious flooding can be expected over southern Pakistan.


Figure 3. Forecast rain amounts for the 18-hour period ending at 2am EDT June 3, 2010. Image credit: NOAA/NESDIS.

Oil spill update
Onshore winds out of the south, southwest, or west are expected to blow over the northern Gulf of Mexico over most of the next week, resulting increased threats of oil to Alabama, Mississippi, and the Florida Panhandle, according to the latest trajectory forecasts from the State of Louisiana. The latest ocean current forecasts from the NOAA HYCOM model show that these winds will generate a 0.5 - 1 mph current flowing from west to east along the Florida Panhandle coast Sunday and Monday. If this current develops as predicted, it will be capable of bringing light amounts of oil as far east as Fort Walton Beach, Florida, by Monday. If you spot oil, send in your report to http://www.gulfcoastspill.com/, whose mission is to help the Gulf Coast recovery by creating a daily record of the oil spill.

Oil spill resources
My post, What a hurricane would do the Deepwater Horizon oil spill
My post Wednesday with answers to some of the common questions I get about the 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
Gulf Oil Blog from the UGA Department of Marine Sciences
Oil Spill Academic Task Force
University of South Florida Ocean Circulation Group oil spill forecasts
ROFFS Deepwater Horizon page
Synthetic Aperture Radar (SAR) imagery from the University of Miami

I'll be back Friday with an analysis of the new TSR hurricane forecast and a new forecast by a promising Florida State University model.

Jeff Masters

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1531. Patrap
Okay Houston,..were hard docked..
Member Since: 3 juillet 2005 Posts: 426 Comments: 129089
Ok i got an interesting but trivial question...Hurricane Audrey was first detected in the BOC as a tropical storm....could Audrey have been a Cross-over storm from the Eastern pacific?
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can someone post the live feed link?

TIA

good evening!
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1527. IKE
There it goes!
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June 17-21 will be the birth of Alex. This is based on looking at conditions 2 weeks from now.
Member Since: 18 mai 2009 Posts: 0 Comments: 474
1525. IKE
How is that top-hat/top-cap...whatever it's called...not going to get knocked all around when it's attempted to be put over the oil flowing out?
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1524. Ossqss
OK, here we go on the cap!

This will work or I will personally drop 21 1/2" lead balls from the surface down there from Tampaspins boat tomorrow!

GTRDN!!!!!
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Here it goes
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1522. Grothar
Quoting louisianaboy444:
Ok i got a trivia question for yall! Can hurricane form in Freshwater lakes...and if so where has one occurred?


Yes, thee Huroncane in 1996.
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is it tangled up in those lines???
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Quoting louisianaboy444:


You are correct sir! Hurricane Huron, 1996
Oh, I searched it up. I thought you were asking a general question, not trivia.
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1519. Patrap


We need Neil,Mike and Buzz on it...
Member Since: 3 juillet 2005 Posts: 426 Comments: 129089
Quoting louisianaboy444:
Ok i got a trivia question for yall! Can a hurricane form in Freshwater lakes...and if so where has one occurred?


The only example I can think of is the Great Lakes tropical entity of 1996.
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Its spewing like an underwater volcano
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Quoting Hurricanes101:


I believe one formed in Lake Huron, not sure of the year


You are correct sir! Hurricane Huron, 1996
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either way
the damage
is done

doesn't really
matter
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Quoting louisianaboy444:
Ok i got a trivia question for yall! Can hurricane form in Freshwater lakes...and if so where has one occurred?
The 1996 Lake Huron cyclone (commonly known as Hurricane Huron, or the Hurroncane) was a strong cyclonic storm system that developed over Lake Huron in September 1996. It had some characteristics of a tropical cyclone.

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1513. aquak9
hello sj and other adults.

adult swim at its toughest.

I wanna swim down there and fix it m'self. Gladly would die doing it if i could.
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Is it stuck against the side.......?
Member Since: 2 septembre 2007 Posts: 179 Comments: 20448
Quoting louisianaboy444:
Ok i got a trivia question for yall! Can a hurricane form in Freshwater lakes...and if so where has one occurred?


I believe one formed in Lake Huron, not sure of the year
Member Since: 10 Mars 2010 Posts: 1 Comments: 7866
It was a cat 5 storm in october a hit florida.I think the year was 1920??
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I think that there is something wrong with this
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Quoting MiamiHurricanes09:
I knew this by heart.

1924 Cuba hurricane. I even know it had winds of 165 MPH. I memorized it a couple months back for some reason.


You win a um hurricane tracking map
Member Since: 10 Mars 2010 Posts: 1 Comments: 7866
Quoting ShenValleyFlyFish:
I want to compliment all on the blog for their disregard of a distraction. At least two manifestations are here tonight and we are doing well sticking to the topic at hand.

I still say those RoV operators rock whatever the outcome.


Everyone does better when there is a distraction. We've got a good group here tonight.
Member Since: 26 avril 2009 Posts: 3 Comments: 3667
1506. pottery
Well, Another Moment of Truth has arrived, in The Deep.
Will it, wont it, stay stressed....
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Ok i got a trivia question for yall! Can a hurricane form in Freshwater lakes...and if so where has one occurred?
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Quoting Hurricanes101:
I got a quiz question

The Earliest recognized CAT 5 hurricane hit what mostly impacted what Landmass (State or Country)?
I knew this by heart.

1924 Cuba hurricane. I even know it had winds of 165 MPH. I memorized it a couple months back for some reason.
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dang that thing is blowing....come on and work....
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1502. IKE
Got it right next to it.
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Evening Aqua, good to see ya! And I second that...Seal that thing up.
Member Since: 17 août 2005 Posts: 26 Comments: 16874
Correct Miamihurricanes.You win a ummmmm free micky mouse plush.Is that good?
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1499. Levi32
Quoting Hurricanes101:
yea you cant really post pics and ask that question

the answer is in the link lol


Oh I forgot about that. But I answered too fast to have looked lol :P
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I got a quiz question

The Earliest recognized CAT 5 hurricane mostly impacted what Landmass (State or Country)?
Member Since: 10 Mars 2010 Posts: 1 Comments: 7866
I want to compliment all on the blog for their disregard of a distraction. At least two manifestations are here tonight and we are doing well sticking to the topic at hand.

I still say those RoV operators rock whatever the outcome.
Member Since: 9 septembre 2007 Posts: 36 Comments: 4687
Quoting Grothar:


It has to be David, that is what is says in the link. LOL
LMAO, I knew someone was going to do that. LOL.
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yea you cant really post pics and ask that question

the answer is in the link lol
Member Since: 10 Mars 2010 Posts: 1 Comments: 7866
Quoting Levi32:


David?
Wow, good job!

Congratulations!

You just won this bottle of Fiji water.

A $5 dollar value!

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1493. Grothar
Quoting Baltimorebirds:
That I yhink is David in 1979


It has to be David, that is what is says in the link. LOL
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1492. aquak9
c'mon c'mon c'mon

tupperware seal that b*%@#
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1491. KEEPEROFTHEGATE (Mod)
Quoting MrstormX:


No more JFV, as a blog I think we decided a couple nights ago... no more
if you speak of it no more it will disappear for sure
Member Since: 15 juillet 2006 Posts: 175 Comments: 54827
Quoting MiamiHurricanes09:
Identify this category 5 hurricane in the Atlantic:



That I yhink is David in 1979
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1489. pottery
Quoting atmoaggie:

A lot of junk out there, BUT, we have an area ridden with refineries in LA called cancer alley. Documented cancer rates and a couple of years off of life expectancy...so there is *some* threat. (But with more monitoring and study, who knows, could be some chemical emission not released anymore, or it is something currently deemed harmless).

Also, though, yeah, the news is perfectly glad to tell the ready-to-believe-anything moronic masses whatever works the fear into a froth.
(Hehe, like a wall of water/oil/flames full of alligators making the MS river change course! lol...see my blog if you don't know what I refer to here.)

Great Blog, Atmo LOLOL
Of course petroleum is toxic. But with good sense, you dont have to get sick being around it. If that was the case, well, there would be a lot less people........
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Quoting MiamiHurricanes09:
Identify this category 5 hurricane in the Atlantic:





David
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they are
trying to
place the
cap
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Quoting MiamiHurricanes09:
Identify this category 5 hurricane in the Atlantic:





Hurricane David
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This is pretty neat. I would love to go up in one. Thought about stowing away on Kermit but they'd probably have caught me. Lol.
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Quoting MiamiHurricanes09:
Identify this category 5 hurricane in the Atlantic:





David
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Quoting Baltimorebirds:
You guys are killing on the blog right now.

Quick trivia

In 2005 hurricane katrina cuased 81.3 bollion dollors on damage.What is the cost now.
$90.1 billion. I used a currency converter :).
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1482. Levi32
Quoting MiamiHurricanes09:
Identify this category 5 hurricane in the Atlantic:





David?
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1481. JamesSA
Drumroll...........................................
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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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