CSU predicts highly active hurricane season; Cyclone Phet approaching Oman
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
Reader Comments
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Agreed.
I think it's going up the tube and exiting into the Gulf twenty feet from where it did 45 minutes ago. No more or less oil. Differant place and pressure
Then they should be forced into a CH 7 liquidation!!
Tropical Cyclone Advisory Number TWENTY-SEVEN
VERY SEVERE CYCLONIC STORM PHET (ARB02-2010)
2:30 AM IST June 4 2010
=======================================
At 21:00 PM UTC, Very Severe Cyclonic Storm Phet over west central Arabian Sea moved northwestward and lays centered near 21.0N 59.0E, or 1050 kms west southwest of Naliya, Gujarat, 960 kms southwest of Karachi, Pakistan, 170 kms south southwest of Sur, Oman, and 70 kms north of Masirah Island, Oman.
3 minute sustained winds near the center is 65 knots with a central pressure of 978 hPa. The state of the sea is phenomenal around the system's center.
The Dvorak intensity of the system is T4.0. Associated broken/solid intense to very intense convection observed over area between 17.5N to 24.5N and west of 62.5E. The lowest cloud top temperature due to convection is about -75C in association with the system.
Vertical wind shear of horizontal wind over the region is low to moderate. The system lies to the south of tropospheric ridge, which roughly runs along 22.0N over the region.
The system is interacting with land surface. Ocean heat potential over the northwest Arabian Sea is relatively less, which is not favorable for intensification.
Considering all the above, the system would move slowly in a northerly direction and cross Oman coast near 21.5N by 06:00-12:00 PM IST, today. It would then weaken gradually, recurve northeastward and then emerge into northwest Arabian Sea by night and move northeastwards towards Pakistan.
Gale winds of 60-70 knots with gusts of 75 knots would occur along and off of Oman coast at the time of landfall.
Storm Surge Guidance For Oman Coast
====================================
Storm surge of about 2 meters above the astronomical tide would occur around the time of landfall.
So what you are saying is this: you would rather have 1 person die, than 150 fish. You are a sick, sick, mind.
Man is what caused what's going on in the GOM. It's man's fault. Greed included. I'm not so sure man is the smartest. In some ways were the dumbest.
Uhhhhh....?
BP: Bong Passers.
yeah...I've been watching almost nightly.
Current Babuska..
I second that emotion.
No, it is a real monkey's head. Used for good luck by BP. Just didn't work out so good for them (or us)
Two things are infinite: the Universe and human stupidity. And I'm not even sure about the Universe. --Albert Einstein
Are you kidding with those comments?
It seems to me that no President since Harry Truman has had so much on his plate.
Yep, we are pretty dumb. Animals get a long fine, we create messes time and time again.
The Atlantic Current can take him back to England the Long way..via the Loop.
He had best be or an angry WU mob is in his future, for sure.
Amen to those comments.
Please post a satellite loop of Phet :O)!!
Nah the loop is breaking off . he can just circulate in the eddy along with all of his oil for a while.
how to answer this. i know that we have fault lines everywhere. i know that an earthquake occurred in the gulf in 2006, which is a rare event and a fault line was found. there is no place on this earth that needs any extra push in order to have serious consequences, especially in the ocean with tons of pressure put on it.
You mean the idiot that said..."I want my life back"?
Well.. another Plane , another President,another Visit,...
I dont even Look Up at the Damn Thing anymore since Sept 2 ,2005.
It's giving us all a headache but it's the only pressing matter right now. What are we to discuss with the tropics? There's nothing happening there.
Well you know what Joe, that ain't good enough.
Dat be da one my Good Neighbor to my East
No reason to be banned from what he was posting unless I missed something.
Congrats for displaying a complete lack of understanding of the situation...
I don't have an answer to that.
I understand why people are focused on the oil spill as it involves all of us. That said I dont entirely disagree with his sentiment. It seems the same folks who complain when we talk about politics or GW because it is "off topic" are also off topic themselves about the Oil Gusher.
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