More pre-season predictions of a very active Atlantic hurricane season

By: Dr. Jeff Masters , 3:02 PM GMT on July 12, 2010

Hello again, it's Jeff Masters back again after a week away. Well, the past week was a wicked hot time to be in New England, where I was vacationing, and I certainly didn't expect to see 98° temperatures in Maine like I experienced! Fortunately, it's not hard to find cold water to plunge into in New England. Thankfully, the tropics were relatively quiet during my week away, and remain so today. There are no threat areas in the Atlantic to discuss at present, and none of the reliable computer models is forecasting tropical cyclone development over the next seven days. The NOGAPS model does show a strong tropical disturbance developing near the waters offshore of Nicaragua and Honduras this weekend, though. With not much to discuss in the present-day tropics, let's take a look at more pre-season predictions of the coming Atlantic hurricane season.

2010 Atlantic hurricane season forecast from Penn State
Dr. Michael Mann and graduate student Michael Kozar of Penn State University (PSU) issued their 2010 Atlantic hurricane season forecast on May 28. Their forecast utilizes a statistical model to predict storm counts, based on historical activity. Their model is predicting 19 to 28 named storms in the Atlantic, with a best estimate of 23 storms. The forecast assumes that record warm SSTs will continue in the Atlantic Main Development Region for hurricanes. Dr. Mann has issued two previous forecasts, in 2007 and 2009. The 2007 forecast was perfect--15 storms were predicted, and 15 storms occurred. The 2009 forecast called for 11.5 named storms, and 9 occurred (the 2009 forecast also contained the caveat that if a strong El Niño event occurred, only 9.5 named storms were expected; a strong El Niño did indeed occur.) So, the 2009 forecast also did well.

2010 Atlantic hurricane season forecast from the UK GloSea model
A major new player in the seasonal Atlantic hurricane season forecast game is here--the UK Met Office, which issued its first Atlantic hurricane season forecast in 2007. The UK Met Office is the United Kingdom's version of our National Weather Service. Their 2010 Atlantic hurricane season forecast calls for 20 named storms, with a 70% chance the number will range between 13 and 27. They predict an ACE index of 204, which is about double the average ACE index.

I have high hopes for the UK Met Office forecast, since it is based on a promising new method--running a dynamical computer model of the global atmosphere-ocean system. The CSU forecast from Phil Klotzbach is based on statistical patterns of hurricane activity observed from past years. These statistical techniques do not work very well when the atmosphere behaves in ways it has not behaved in the past. The UK Met Office forecast avoids this problem by using a global computer forecast model--the GloSea model (short for GLObal SEAsonal model). GloSea is based on the HadGEM3 model--one of the leading climate models used to formulate the influential UN Intergovernmental Panel on Climate Change (IPCC) report. GloSea subdivides the atmosphere into a 3-dimensional grid 0.86° in longitude, 0.56° in latitude (about 62 km), and up to 85 levels in the vertical. This atmospheric model is coupled to an ocean model of even higher resolution. The initial state of the atmosphere and ocean as of June 1, 2010 were fed into the model, and the mathematical equations governing the motions of the atmosphere and ocean were solved at each grid point every few minutes, progressing out in time until the end of November (yes, this takes a colossal amount of computer power!) It's well-known that slight errors in specifying the initial state of the atmosphere can cause large errors in the forecast. This "sensitivity to initial conditions" is taken into account by making many model runs, each with a slight variation in the starting conditions which reflect the uncertainty in the initial state. This generates an "ensemble" of forecasts and the final forecast is created by analyzing all the member forecasts of this ensemble. Forty-two ensemble members were generated for this year's UK Met Office forecast. The researchers counted how many tropical storms formed during the six months the model ran to arrive at their forecast of twenty named storms for the remainder of this hurricane season. Of course, the exact timing and location of these twenty storms are bound to differ from what the model predicts, since one cannot make accurate forecasts of this nature so far in advance.

The grid used by GloSea is fine enough to see hurricanes form, but is too coarse to properly handle important features of these storms. This lack of resolution results in the model not generating the right number of storms. This discrepancy is corrected by looking back at time for the years 1989-2002, and coming up with correction factors (i.e., "fudge" factors) that give a reasonable forecast.

The future of seasonal hurricane forecasts using global dynamical computer models is bright. Their first three forecasts have been good. Last year the Met Office forecast was for 6 named storms and an ACE index of 60. The actual number of storms was 9, and the ACE index was 53. Their 2008 forecast called for 15 named storms, and 15 were observed. Their 2007 forecast called for 10 named storms in July - November, and 13 formed. A group using the European Center for Medium Range Weather Forecasting (ECWMF) model is also experimenting with some promising techniques using that model. Models like the GloSea and ECMWF will only get better as increased computer power and better understanding of the atmosphere are incorporated, necessitating less use of "fudge" factors based on historical hurricane patterns. If human-caused climate change amplifies in coming decades, statistical seasonal hurricane forecasts like the CSU's may be limited in how much they can be improved, since the atmosphere may move into new patterns very unlike what we've seen in the past 100 years. It is my expectation that ten years from now, seasonal hurricane forecasts based on global computer models such as the UK Met Office's GloSea will regularly out-perform the statistical forecasts issued by CSU.

2010 Atlantic hurricane season forecast from Florida State University
Last year, another group using dynamical computer forecast models entered the seasonal hurricane prediction fray. A group at Florida State University led by Dr. Tim LaRow introduced a new model called COAPS, which is funded by a 5-year, $6.2 million grant from NOAA. This year, the COAPS model is calling for 17 named storms and 10 hurricanes. Last year's prediction by the COAPS model was for 8 named storms and 4 hurricanes, which was very close to the observed 9 named storms and 3 hurricanes.

Summary of 2010 Atlantic hurricane season forecasts
Here are the number of named storms, hurricanes, and intense hurricanes predicted by the various forecasters:

23 named storms: PSU statistical model
20 named storms: UKMET GloSea dynamical model
18.5 named storms, 11 hurricanes, 5 major hurricanes: NOAA hybrid statistical/dynamical model technique
18 named storms, 10 hurricanes, 5 intense hurricanes: CSU statistical model (Phil Klotzbach/Bill Gray)
17.7 named storms, 9.5 hurricanes, 4.4 intense hurricanes: Tropical Storm Risk (TSR), hybrid statistical/dynamical model technique
17 named storms, 10 hurricanes: FSU dynamical model
10 named storms, 6 hurricanes, 2 intense hurricanes: climatology

Only four hurricane seasons since 1851 have had as many as nineteen named storms, so 5 out of 6 of these pre-season forecasts are calling for a top-five busiest season in history. One thing is for sure, though--this year won't be able to compete with the Hurricane Season of 2005 for early season activity--that year already had five named storm by this point in the season, including two major hurricanes (Dennis and Emily.)

Tropical Storm Conson threatens the Philippines
Weather456 has an interesting post on why the Western Pacific typhoon season has been exceptionally inactive this year. It looks like we'll have out first typhoon of the Western Pacific season later today, since Tropical Storm Conson appears poised to undergo rapid intensification, and should strike the main Philippine island of Luzon as a Category 1 or 2 typhoon.

Next post
I'll have an update Wednesday.

Jeff Masters

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Quoting btwntx08:
also the carribean waters are much warmer now than last yr but the gom is a tad cooler than last yr which is wierd

Because of Alex...Alex cooled the whole GOMEX, just not as much as the area it tracked directly over.
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Quoting CBS4:
Where's Levi, gang?

I dont know, wherever Levi's go.
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Levi is probably doing his studies. I think he's got a heavy schedule over the summer.
I haven't seen Pottery around for a few days, either.
Goofed around long enough.
Back to the endless details called work.
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StormW posted something yesterday about bigger waves being less affected by SAL. Am sure it's been said before, but what is interesting about the African wave is there is another one right behind it in case the first one dissipates.
Meteosat - East Atlantic - Rainbow Loop
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Quoting IKE:
Yep, looks like an Atlantic Desert as Patrap noted, but consider all of the heating taking place during this lull.
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Thanks Dr. Masters and welcome back…

Just arrived back from our vacation as well yesterday, Mexico Beach, Florida. Good time had by all, especially our grandson. Pretty good weather with the exception of being rained on during a couple motorcycle rides
through Apalachicola National Forrest.

Ike…saw the storm that dumped on you…I received
a new flash memory HD camcorder for Father’s Day…It has a time lapse feature, so I recorded pop-up storms…you get quite a different perspective of convective build-up with this technique.

Everyone take care and be safe…

Very Respectfully,

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you are right TropicalAnalystwx13 let me change it up a little

Wow there is some nice vort at 850 with our wave that as been on stand still for the past 24-36 hours just west of Africa west coast :)
Member Since: June 13, 2009 Posts: 2 Comments: 15656
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GOM and Tropics Low Cloud Product GOES-12
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5-Day Atlantic SAL Movie
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Dry Air is not really affecting the African wave like people think...
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False, see Post 85. Thanks
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187. IKE
Quoting Patrap:
The Atlantic Desert ?

Looks that a way to me too.
Member Since: June 9, 2005 Posts: 23 Comments: 37995
The Atlantic Desert ?
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that blob if it does anything it will be a fish system should move off to the NE
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Quoting melwerle:

My stupid question of the day - I realize that we're supposed to have earthquake kits like folks have hurricane kits. But where exactly are you supposed to KEEP them. If your house falls in, it would be kind of hard to get it out of the house and I'm not sure keeping bottled water outside in the sunshine is such a great idea either. Any tips?

If your house falls in, you will have bigger problems. I store most of the water in a walk-in space underneath an interior stairwell. Food in a large pantry. First aid kit with the water. And a few bottles of water scattered about the house. I have nothing stored outside. Wouldn't hurt, but rotate any water out there often and protect it from sunlight with a light-colored tarp. High quality filtered water will last longer than tap water.

I do keep some water and food, and a smaller first aid kit, in my vehicle. That is probably the best choice for "outside" if you have room ... you may not be at home when the "big one" hits and getting home may be a challenge.
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182. IKE
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Quoting BFG308:

I mean this with no malice intended but having someone quote you so someone who ignored will read what you say defeats the purpose of the ignore function. Factual statement. I mean no harm

Really. Until you quoted him, I wasn't aware there WAS a post #74.
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Quoting wunderkidcayman:
Wow there is some nice vort at 850 wi5th our wave that just came off of Africa

today now

24 hours ago

It didn't just come off, its been off for days...
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177. IKE
200 PM EDT MON JUL 12 2010




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Quoting stillwaiting:
I'm begining to think this next wave thats going to exit africa is going to be trouble,this will be the wave that should form into this years first CV TC!!!

I believe they both have the potential to develop, although I do think that the second one has a slightly better chance.
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Wow there is some nice vort at 850 wi5th our wave that just came off of Africa

today now

24 hours ago

Member Since: June 13, 2009 Posts: 2 Comments: 15656
The gulf spill would cover CONUS with 67 gallons per square mile. That sounds really high. Or it could cover the entire CONUS with roughly a nanometer of oil. That sounds a lot smaller (still outrageous, for sure). Numbers are very deceiving for people, especially when they come from someone with an opinion
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I'm begining to think this next wave thats going to exit africa is going to be trouble,this will be the wave that should form into this years first CV TC!!!
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Quoting truecajun:

someone told me that the amount of oil released into the GOM wouldn't fill the superdome. i find this hard to believe. has anyone else heard this?


1. Superdome Interior Volume = 125,000,000 Cubic Feet

2. US Petroleum Barrel = 5.6 Cubic Feet

3. Superdome US Petroleum Volume = 22,321,428 Barrels

4. High Side Estimate Total of BP GOM Spill Volumes = 5,040,000 Barrels

5. After 1st 84 days, the N.O. Superdome would be only 22.6% Full !!!!!

6. Gulf of Mexico = 15.3 Quadrillion Barrels of Water

7. Thus, GOM Could Hold = 685,901,200 Superdomes!

8. OR, At the Current 60,000 bbls\day Spill Rate, it would take almost 686 MILLION YEARS to Displace the GOM!

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Where's BahaHurricane? Or KmanIslander. They're usually pretty good at the stuff that develops close by. Looks like an AOI at 2 p.m.
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168. MahFL
Quoting btwntx08:

yea i doublechecked as well it is 25 kts still a tad to high

One part only has 20 Kts though.....
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165. 7544
THANKS ALL BUT AFTER SEEING WHERE katrina started the bahammas blob got my attention today

and yes jeff i agree the gfs shows the 3 systems aiming right at so fla . seson starting this month we will have lots to watch the sterring does not look good for people in so fla or the se states wait watch and see .
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Quoting BFG308:
Tampa Tom- I got similar numbers. It doesn't take a chemical engineer to use wikipedia and a calculator to make some great approximations

I call it 'Kentucky Windage' :-)

Wiki sez 32,000,000 gallons for The Valdez... Ruffly 3.5% of the volume of the Superdome...
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Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather

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