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

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

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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 MiamiHurricanes09:
Who remembers when hurrkat05 (stormtop) came on here yesterday afternoon and constantly stated that invests were having a tough time forming 'shear'? She then preceded to tell StormW and me to watch and learn. Ahhhh, good times. He's a "shearcaster".
That sounds funny.That reminds me of debbykat.......
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Quoting earthlydragonfly:
I just re-read the email and it is this image..


Wow thats a nice Shot there DragonFly :o)
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2461. JRRP
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Quoting Baltimorebirds:
Another jfv attack is going on the blog?


Nah, just a case of the sillies.... StormW starteded it....
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2458. gator23
Quoting AussieStorm:

I would call them a wishcaster... wishing they were as good as a forecaster as you and StormW

dilusionalcaster
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Quoting FLdewey:
Wait a minute. HOLY CRAP I had no idea... just found the REAL map:



LOL!
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Quoting MiamiHurricanes09:
Who remembers when hurrkat05 (stormtop) came on here yesterday afternoon and constantly stated that invests were having a tough time forming 'shear'? She then preceded to tell StormW and me to watch and learn. Ahhhh, good times. He's a "shearcaster".

I would call them a wishcaster... wishing they were as good as a forecaster as you and StormW
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I just re-read the email and it is this image..

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2454. gator23
Quoting fire831rescue:


Yes, it does.. But they are combined. They're called "Texaco" and are represented by a big red star with a T in the middle of it,


LOL!!!!! Is Bob Hope their spokesman/governor (I may have dated myself here)
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Another jfv attack is going on the blog?
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Quoting TropicalAnalystwx13:


Central Africa:


Hello, Central Africa looks like it's being attacked by one NASTY/MEAN looking wave of convection.
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Quoting StormW:


We won't go into detail as to what kind of caster on this one.
Interesting Storm...

LOL!
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting AussieStorm:

Does it have Mexico and Texas on it???


Yes, it does.. But they are combined. They're called "Texaco" and are represented by a big red star with a T in the middle of it,
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2449. gator23
Quoting Patrap:
.."Lego my Ego".. caster?

ego or eggo? both work I just want to clarify.
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Quoting StormW:


Ok...someone wanna tell the fake Gulf of Mexico to knock it off, and quit being an impostor!


lol
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Quoting StormW:


I must have, LOL! Just figured, rather have humor on Doc's blog while it's dead, instead of all the bickering that's been ongoing.


The voice of Wisdom!!! Hear, hear!

Storm, I doff my cap...eh...my...er... OK paws up and tailwags all around!
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For More information please click here
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Ill be honest... I didnt think everyone would get so into the Iwannabeacaster game.. Im glad most are having fun with it..

Oh by the way, Marketing from Wunderground sent me an email today asking me for permission to use one of my pictures in some of their media.. I haven't responded yet but thought it was pretty cool!! And I dont know what shot they want yet.
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2443. Patrap
.."Lego my Ego".. caster?
Member Since: July 3, 2005 Posts: 426 Comments: 129089
Quoting TropicalAnalystwx13:


Central Africa:

All I see is a mess of clouds over africa.
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Who remembers when hurrkat05 (stormtop) came on here yesterday afternoon and constantly stated that invests were having a tough time forming 'shear'? She then preceded to tell StormW and me to watch and learn. Ahhhh, good times. He's a "shearcaster".
Member Since: September 2, 2009 Posts: 130 Comments: 21194
2439. xcool


Member Since: September 26, 2009 Posts: 2 Comments: 15684
2438. gator23
Quoting fldude99:


I'm talkin about the real GOM..LA to FL

I would say that Fla is more of a "fake GOM state" since half of our coast is in the Atlantic. The other states coats are ALL GOM
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Quoting FLdewey:
Wait a minute. HOLY CRAP I had no idea... just found the REAL map:



Argh, matey!! Whar's ye treasure be? Be there an X on yer map, matey?
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Quoting FLdewey:
Wait a minute. HOLY CRAP I had no idea... just found the REAL map:


Does it have Mexico and Texas on it???
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Quoting helove2trac:
if we dont hurry n get something brewing we will all be nut-casters

And the blog will become full of bust-casters
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Quoting StormW:
Ya know gang, I hope that Admin is laughing at all of this!

They probably are StormW :o)
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During active periods of hurricane season, these rules will be strictly enforced. Violations will be met with a minimum 24 hour ban.

At least they didn't say INACTIVE periods. LOL.
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2431. FLdewey
Wait a minute. HOLY CRAP I had no idea... just found the REAL map:

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Quoting earthlydragonfly:
Ok Now everyone must pick their favorite ???caster handle and make a new identity. That way when JFV, Stormtop or who ever come in they will not know who to tick off.

Wouldnt that just be awesome..
I pick this one:

"Senior-chief-is-this-one-a-Florida-thretter?-caster."
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting StormW:
Ya know gang, I hope that Admin is laughing at all of this!


I think most folks, including admin, are glad we can laugh a bit now. That may not be true in a few weeks....
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2427. gator23
Quoting earthlydragonfly:
Ok Now everyone must pick their favorite ???caster handle and make a new identity. That way when JFV, Stormtop or who ever come in they will not know who to tick off.

Wouldnt that just be awesome..

calmcaster
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Ok Now everyone must pick their favorite ???caster handle and make a new identity. That way when JFV, Stormtop or who ever come in they will not know who to tick off.

Wouldnt that just be awesome..
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if we dont hurry n get something brewing we will all be nut-casters
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We've always messed around during inactive periods of hurricane season like now. Admin's cut us slack, but when it ramps up.. Admin's are quick to give out bans.
Member Since: July 8, 2005 Posts: 259 Comments: 24457
StormW, did you take some silly pillies? LOL. You're on a roll tonight...
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2422. Patrap
.."their's"
Member Since: July 3, 2005 Posts: 426 Comments: 129089
Quoting StormW:


Tidal wave caster! LOL! (No offense fly!)
LOL!
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2420. JLPR2
Quoting StSimonsIslandGAGuy:


I guess Texas and Mexico are on the fake GOM?

That's just ridiculous.


NO, that's hilarious! XD
Specially since its named the Gulf Of Mexico LOL!
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Quoting FLdewey:


Maybe for Christmas we'll all pitch in and buy you a globe.

also a pair of glasses and the rest of there brain. geez some people. as i said befor, they only care about there state, only 1 state that boarders the GOM to them,,, their's
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2418. Patrap

Current Conditions

Manila, PH (Airport)
Updated: 9 min 59 sec ago
Mostly Cloudy
82 °F
Mostly Cloudy
Humidity: 89%
Dew Point: 79 °F
Wind: 10 mph from the ESE
Pressure: 29.74 in (Steady)
Heat Index: 92 °F
Visibility: 5.0 miles
UV: 8 out of 16
Clouds:
Few 2200 ft
Scattered Clouds 2300 ft
Mostly Cloudy 10000 ft
(Above Ground Level)
Elevation: 69 ft
Member Since: July 3, 2005 Posts: 426 Comments: 129089
2417. xcool
HEY JFV
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting StormW:
Ya know gang, I hope that Admin is laughing at all of this!
Hopefully...

Member Since: September 2, 2009 Posts: 130 Comments: 21194

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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.

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