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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hahahahah
:)
whoops, I thought you were making a joke that the Oil Spill had its own Facebook page. My bad. Kinda' funny though(?) Think I need an early beer...good, it IS after noon...okey dokey then...
Not an invest yet, and will never be if it doesn't make it over the water. It's forecasted to hug the coast so it will be a close call on whether it moves over the gulf. Even then, MCVs do not always spark tropical mischief, and can easily just die out. We'll see if it regenerates itself tonight. It has strong upper support.
Follow your instincts.........
:)
nah...it's just that missing photo of Marilyn Monroe and JFK...little did OZ know, they busted into his envelope and exposed the truth. Dang it big brotha!
You mean just west of Africa? That one isn't really a problem in my opinion.
If it is anything like this morning will be interesting. Just not too interesting. :)
wonder if that could spark some development
Testing admin again are we? You do remember the fans don't you.
They have medecine for that now, oz...
hahaahahahah
Both
Hey Storm, what do you think about the situation Levi is monitoring with the system over Texas?
lol
Religion doesn't belong on a Tropical Weather forum. We are here to discuss storms, atmospheric conditions and weather anomalies from a physical sciences perspective. Tropical storms don't have souls, so I'm not concerned about the moral implications and spiritual aspects of a tropical storm.
Tropical storms also do not have party affiliations. They are decidedly Independent... not aligned with either the Dem or Rep parties. Tropical Storms have both left and right leaning aspects and are known for making their own path. As such, we should not be discussing politics in regard to Tropical Storms.
Sheeesh! Can we stick to discussions about the weather, earthquakes, Gulf oil spill, humanitarian aid and everyone's health?
CATL Visible Loop
Previous discussion... /issued 653 am CDT Thursday Jun 3 2010/
561
fxus64 klix 031407
afdlix
Area forecast discussion
National Weather Service New Orleans la
907 am CDT Thursday Jun 3 2010
Aviation...
mesoscale convective system continues to make eastward progression at nearly 40 knots and
nearing a kjas-klch-to 96 miles SW of khum as of 1130z. Mcb has
fallen to LIFR but should be short lived. Otherwise is VFR across
the region with cirrus blow off quickly overspreading the region.
The mesoscale convective system should reach the btr/hum vicinity close to 14-15z and msy/new
15-17z. Scattered rain showers and isolated thunderstorms and rain could develop ahead of the mesoscale convective system
and traverse the taf sites prior to the arrival of the mesoscale convective system and winds
briefly swinging to the west. Am expecting rain showers and thunderstorms and rain to taper
off 18z thanks to the mesoscale convective system stabilizing the airmass over most of the
south. Mcb could easily have thunderstorms and rain ongoing late in the afternoon.
Skies remain broken thanks to cirrus well into the evening then should
clear somewhat. Latest NAM indicating a surface low very slowly
trekking east from the Sabine River Friday morning so may need to
add mention of rain showers to btr after 10z. Lingering rain showers possible east
of msy to near mob with ll convergent flow after 10z as well.
Keep
yea this feature should move mostly E to ENE
Reminds me of the one a few years back
There was a rogue line that ripped through parts of southern Texas and came off the coast
about 14 hours later this same line hit the west coast of Florida
Its a MCS..nothing tropical will come from it.
EXTENDED-RANGE FORECAST OF ATLANTIC SEASONAL HURRICANE ACTIVITY AND LANDFALL STRIKE PROBABILITY FOR 2010
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