CSU predicts highly active hurricane season; Cyclone Phet approaching Oman

By: Dr. Jeff Masters , 2:00 PM GMT on June 03, 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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Quoting CycloneOz:


Are you not reading what I'm saying.

The other attempts, apparently, were forced on them by the government! They were forced to make those specific attempts! They were not "allowed" to cut the pipe until yesterday!

We dont KNOW that yet...
Member Since: October 24, 2005 Posts: 0 Comments: 24001
Quoting hydrus:
Hello Oz. I make a mean lasagna myself. But yours sounds damn good. Now I am hungry. I wish you and your colleagues a safe season of chasing.


!Gracias! mi amigo! :)
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Quoting sarahjola:
does anyone know if mandeville louisiana will actually see a thunderstorm today


Would someone please direct this poor, misguided soul to a weather blog? (Just messin' with you, Sarah.)

Gosh, I've missed this place.
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I was just about to mention that flare up above haiti...
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Quoting CycloneOz:


LOL...yeah...I'm an Italian cook! :)

(We just catered our daughter's high school graduation party featuring lasagna and meat sauce. I witnessed an 18-year old boy's knees buckle when he took his first bite of the entree. He wound up eating half a pan.)
Hello Oz. I make a mean lasagna myself. But yours sounds damn good. Now I am hungry. I wish you and your colleagues a safe season of chasing.
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Quoting CrozetDutch:


One dollar gas? Please, just to appeal to more irresponsible use of Earth's limited resources? And, it really does not help the victims of this disaster. The best way to ensure the funds for the massive clean up and restitution: seize BP or put it in a receivership, get rid of all the execs, and use the billions of proceeds of BP's sale.
You're forgetting one small detail: BP has not be charged or convicted of anything. All of you "somebody get a rope" types need to settle down...your mud slinging is getting all over my copy of the constitution. How 'bout we just line up all BP exec's and shoot them?...sheesh
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The blog has gone completely nuts today. We really need something tropical to watch, and soon.
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Quoting Levi32:


It's rather hard to say. There is no clear path out into the gulf, yet the trough may try to dig southward and get over the water, which the GFS shows happening for at least a short while. The thing has already slowed down considerably, but it's really not that far away from the coast. It could easily slip over the water sometime in the next 3 days.


Well I can at least enjoy the lower temps. :)

FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAKE CHARLES LA
1033 AM CDT THU JUN 3 2010

.UPDATE...
LARGE MCC OVER TX OVERNIGHT GENERATED A LARGE LINE OF SHRA/TSRA TO MOVE
THRU THE REGION EARLIER THIS MORNING...NOW FROM ALEXANDRIA THRU JUST
E OF LAFAYETTE TO MORGAN CITY. FURTHER WEST...THE UPPER TROF THAT
HAS BEEN AFFECTING THE REGION HAS CUT OFF INTO AN LOW...SPINNING
ACROSS SE TX. SCT SHRA/TSRA CONTINUES ACROSS THIS REGION AS WELL.
WITH THIS LOW NOT EXPECTED TO MOVE MUCH...INCREASED INSTABILITY
ALOFT WILL CONTINUE A BETTER THAN AVERAGE (50-60%) CHANCE OF
SHRA/TSRA OVER ALL OF THE REGION. WITH ALMOST TOTAL CLOUD COVER
EXPECTED TO CONTINUE TODAY...TEMPS WILL NOT LIKELY RISE PAST THE
LOWER 80S. UPDATED FORECAST ALREADY OUT.
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Quoting rainingnimbus:

I've got junky in this one, though. He's the perfect height for my reaching left hook to the jaw!

I've read this blog a long time and never seen anyone threaten another like that. Completely wrong.


Oh puhlease. We're friends and he knows I was making a tall joke.
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Quoting DestinJeff:


do you suspect it to remain on-shore low pressure over the coming days?


It's rather hard to say. There is no clear path out into the gulf, yet the trough may try to dig southward and get over the water, which the GFS shows happening for at least a short while. The thing has already slowed down considerably, but it's really not that far away from the coast. It could easily slip over the water sometime in the next 3 days.
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does anyone know if mandeville louisiana will actually see a thunderstorm today
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Quoting Levi32:


Isn't that a cool pic! You'd swear it looks like a TS moving ashore!
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Quoting DestinJeff:


Naturally it is the left side of the pipe that is causing the problems!

SARCASM FLAG: ON.

Well, thats a Brilliant observation.
But it just goes to show that really, it ALL depends on camera angle....
heheheheheh I love this blog.
Member Since: October 24, 2005 Posts: 0 Comments: 24001
In
Quoting AussieStorm:

Try these links.
Link

Link

Link




In that first link, the ROV just dropped the saw! Im sure its attached to something but it was cutting something and then it just flew out of the robot hand thing while it was still turned on.
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can anyone tell me if the system in the gulf is going to effect the spill?
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Quoting theman13:


That is an amazing idea! All BP oil is reduced by 1 dollar per gallon or more for the gulf states. Helps BP (because people would buy their gas again) and helps us too.

Although this would never happen because its probably more complicated than I wish it was.


One dollar gas? Please, just to appeal to more irresponsible use of Earth's limited resources? And, it really does not help the victims of this disaster. The best way to ensure the funds for the massive clean up and restitution: seize BP or put it in a receivership, get rid of all the execs, and use the billions of proceeds of BP's sale.
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Shear that flap! Shear that flap!
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Quoting srada:


Im sorry but it has 43days since the oil spill and all this could have been avoided if BP wasnt CHEAP and fixed the oil rigging problems..this has everything to do with REGULATION and BP was trying every little thing to avoid adhering to Regulation laws..now if this latest escapade dosent work, who will you blame? still the government?


I have never said that BP is not at fault (or some percentage thereof) for the initial disaster.
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Less politics, more Tropical Weather please.

This entire year until Nov. 4th will be filled with politics; Left blaming the Right & vice-versa, finger pointing, etc... . There are plenty of blog sites you can go to for that.

Can we agree that this may become a really active Atlantic Tropical Storm Season and that we have a historically large oil spill in the Gulf just South of several state's coastlines? We should focus our discussions on that and keep politics off the W.U. Tropical Discussion board.
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Quoting Levi32:


Well I don't want to give the GFS that much credit lol. No model detected this surface low before the MCV formed, because it was a mesoscale feature.


And we have seen several times in the past, systems form this way
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253. srada
Quoting CycloneOz:


Dude! If this pipe cut #1 method of BP's works...what will you say then? That it is BP's fault that they didn't do what the government told them to do.

Get real!


Im sorry but it has 43days since the oil spill and all this could have been avoided if BP wasnt CHEAP and fixed the oil rigging problems..this has everything to do with REGULATION and BP was trying every little thing to avoid adhering to Regulation laws..now if this latest escapade dosent work, who will you blame? still the government?
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Impressive 850mb vorticity with the old MCV's circulation:

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Quoting Hurricanes101:
Levi, I think that may have been the scenario the long-range GFS had

Remember about a week ago for a few runs it had a system in the NW Gulf?


Well I don't want to give the GFS that much credit lol. No model detected this surface low before the MCV formed, because it was a mesoscale feature.
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hey tampaspin thanks for putting all the feeds in one spot. my work only allows me an hour "quota" time on cnn but your site doesnt :)
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Levi, I think that may have been the scenario the long-range GFS had, MVS interacting with moisture from the EPAC could spark a weak system.



Remember about a week ago for a few runs it had a system in the NW Gulf?
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Quoting hurricanejunky:


The risk assessment probably looked terrible from the outset which is why it hasn't been tried to now. YOU get real...


Ooooo...a risk assessment.

You've got bureaucrats telling an oil company how to stop an oil gusher.

I love your videos! :)
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Quoting theman13:


That is an amazing idea! All BP oil is reduced by 1 dollar per gallon or more for the gulf states. Helps BP (because people would buy their gas again) and helps us too.

Although this would never happen because its probably more complicated than I wish it was.

That makes no fiscal sense at all. So let's drive the demand for their gas up, drive competition out of business, and reward them with in store purchases.
Do some people think?
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thanks tampa!
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Quoting CyclonicVoyage:
Where's a dremmel tool when you need one? Works wonders around my house.


We need one of those Fein Multimasters they sell on TV. They can remodel your bathroom with no other tools... the should be able to work for this!
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Quoting hurricanejunky:


Yes and how many times has BP tried and failed?


Are you not reading what I'm saying.

The other attempts, apparently, were forced on them by the government! They were forced to make those specific attempts! They were not "allowed" to cut the pipe until yesterday!
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Quoting frostynugs:
why is bp censoring the video stream? it was color bars last night, now just a blank screen with "no video". they don't want us to see exactly how much more oil is gushing out now that they cut the pipe...


Go to my site......have all the live feeds up
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Quoting frostynugs:
why is bp censoring the video stream? it was color bars last night, now just a blank screen with "no video". they don't want us to see exactly how much more oil is gushing out now that they cut the pipe...

Try these links.
Link

Link

Link
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Quoting CycloneOz:


Ocean current, ROV, spinning blade...and you're looking for accuracy here? :D


Hey, man, I can split the line on my table saw... ;-)
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Quoting CycloneOz:


Dude! If this pipe cut #1 method of BP's works...what will you say then? That it is BP's fault that they didn't do what the government told them to do.

Get real!


The risk assessment probably looked terrible from the outset which is why it hasn't been tried to now. YOU get real...
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Where's a dremmel tool when you need one? Works wonders around my house.
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I was referring to the live feed that every news site and such has been using... the pbs feed.
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Quoting TampaTom:


OF course, it seems as if the guy working the saw can't cut a straight line if his life depended on it...


Ocean current, ROV, spinning blade...and you're looking for accuracy here? :D
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Quoting CycloneOz:


Whatever happens...it's happening today. We'll know soon enough.


Yes and how many times has BP tried and failed? And how many times has everyone been jazzed up only to be let down? BP, who caused the mess and should have the technology on hand to immediately stop it, can't stop it! How does that reflect on the "private sector" competency level? Not very well I'm afraid...
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Quoting CycloneOz:


My feed is working perfectly. It's saw blade against pipe right now.


OF course, it seems as if the guy working the saw can't cut a straight line if his life depended on it...
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Quoting frostynugs:
why is bp censoring the video stream? it was color bars last night, now just a blank screen with "no video". they don't want us to see exactly how much more oil is gushing out now that they cut the pipe...


My feed is working perfectly. It's saw blade against pipe right now.
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Quoting Ossqss:
Here is a test for ya. Stare at the center + and make the pink dots go away! It may surprise you and Yes you can!

Just a slight mid day distraction showing how we can impact our own view of things :)



yep did that, less than a few seconds
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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.