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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Yep. unless there is obstruction we dont know about.
Trinidad 11n 61w
...when JFV says sir :P
are you originally from the states?
Yeah, you wish you could reach my jaw with that sorry left hook of yours. Are you gonna lighten up there Yin, or is it Yang? :)
D'oh!!!!!
:)
LOL
12z NOGAPS 180 hours:
No. Been here since 1817.
(in one genetic form or the other!)
GFS Ensembles 500mb height anomalies Day 9:
That's what I was saying earlier.
Move the saw (or maybe just the camera) to the other side.
The Left is more progressive, dont you know...
heheheheh
I have the HPC Link..
LOL
If this were to come out over the gulf and develop it might be interesting to view the satellite loop in reverse and see if it looks like a landfalling TS lol.
It wouldn't be quite right...but would still look interesting.
SHHHHH...stop saying his name...
It implies more convective activity in the western Caribbean as tropical waves start piling into the area.
...or a right wing ideologue...
It could dissipate prior to its arrival.
If this does not work, we will all probably witness the biggest "live" confirmation experiment thus far on the Earth on the question or oil spiil v. hurricane and the resultant effects........We are all hoping for the best today however.....
By Allen Powell II, The Times Picayune
June 03, 2010, 11:58AM
Citing a law typically used against fishers and hunters who exceed legal limits, Plaquemines Parish District Attorney Charles Ballay has sued British Petroleum and its subsidiaries in state court for damages caused by the Deepwater Horizion oil spill to the parish's wildlife.
Ballay's suit, which was filed in 25th Judicial Court on Tuesday, joins a growing number of lawsuits filed against the oil company for damages the leak has caused to local businesses and parishes. In a press release distributed Thursday, Ballay said that Louisiana hunters and fishers are punished whenever they illegally kill or damage the state's wetlands, and BP should be held to the same standard.
"It is only fair that this statute and penalty be used against BP and other responsible parties for this catastrophic loss since it is used on individuals on a regular basis for doing damage to our wildlife, such as when someone catches over the limit of redfish or trout," Ballay said in the news release. "A major corporation that does the damage that we have incurred should certainly be held accountable."
Louisiana law allows BP to be cited for all wildlife killed and the company would then have to pay a civil penalty for each animal, Ballay said. The lawsuit says that dead fish, birds and other wildlife have been washing ashore in Plaquemines Parish.
Now, now, Amy.
You see your prejudice and personal preference is showing.
Flies and maggots and stuff think I smell just fine.
Who is to decide what is foul and what is sweet?
A heckuva lot better than it does contaminating our precious Gulf!! We're gonna have some wicked burning ocean chase video this season! LOL! (cries while laughing)
fxus64 khgx 031727 aaa
afdhgx
Area forecast discussion...updated for aviation
National Weather Service Houston/Galveston Texas
1230 PM CDT Thursday Jun 3 2010
Update...
increased probability of precipitation for today/this evening based on ongoing trends. It
would appear that not a whole lot of heating is required (nor re-
covery time) due to the proximity of the upper low itself. Whilst
this latest band of precipitation is occurring over locations that did not
receive a lot overnight...will go ahead and mention locally heavy
rainfall possible as there is a good chance coverage will fill in
as the day wears on. 41
&&
Aviation...
a low confidence forecast. Upper low over Houston will drift slowly
east southeast. Models typically handle these systems very poorly.
Both NAM/GFS have trended wetter on the 12z run. Given large expanse
of precipitation...even if low moves toward Texas/la border as advertised
think swath of precipitation and scattered convection will still affect
Houston terminals through the day Friday. Have tempoed rain showers/thunderstorms and rain
through 22z...then generally kept vcsh/thunderstorms in the vicinity for the remainder of the
period. Confidence is highest that northwest areas around kcll will
dry out this evening so kept this area dry after 02z. Periods of
MVFR ceilings are likely through Friday morning as low clouds wrap
around the upper low. West to northwest winds of 8-12 kts are
expected.
35
Don't see how an overland low could transition to a warm cored tropical storm....Unless I'm missing something here......
This actually quite frequent can spark tropical development
No, it is not warm-core, and it is unlikely to make such a transition over land. One of the reasons is because any rainfall at the center will perpetually cool the core of the system in the low-levels. You can see this by looking at surface temps, which are much hotter away from the low because of sunshine, but cool underneath the rain shield. The upper levels are cold-core because of the low aloft, and that won't be going away because over land, the system won't be able to generate enough convection to warm the upper levels of the air column.
Viewing: 451 - 501
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