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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Calling Bonnie out of Central Africa is actually very conservative.
The general concensus is and was, we are sitting on a tinderbox.
I believe God has spared the Gulf of Mexico long enough to see if BP can possibly redeem themselves, with some help.
We've got about another week, maybe 2 if we're lucky, imo.
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2362. xcool
StormW WHY LMAO ??
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Chicklit: It makes sense for the Central African wave if not the current one just seen on sat24. The other weaker waves have eroded some of the dry air and there is even more moisture coming from Central Africa. In addition, the Bermuda High is relocating so the WalMart Supercenter can supplant the SAL.
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Quoting StormW:


Ok,
Little tidbit.
Yes little tidbit...lol.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
well right about now i am a bonniecaster
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A huge severe weather outbreak should be expected tomorrow
Member Since: July 6, 2010 Posts: 108 Comments: 30251
If I book a trip to Jamaica and forecast a storm there, is that vacationcaster? vacaycaster?
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Quoting StormW:


Want a little tidbit?
Sure!
Member Since: September 2, 2009 Posts: 130 Comments: 21032
Quoting TropicalAnalystwx13:
I believe Tropical Storm Bonnie will form from the Central African wave if something else doesn't. I still highly believe we will see Colin by August 1st.

Central African?
You're really going out on a limb there.
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Quoting StormW:
MiamiHurricanes09,
You still on?
Yup.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
2350. beell
Quoting gulfcoastdweller:


Hey Babe,

thks for the link, good to see ya!!


Hiya, gcd.

It's an epic battle 5,000' beneath the sea.
Anybody that has ever owned anything that spins around fast...and some string...has been there.
'cept for the 5,000' part1
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Quoting Dakster:


I noticed you didn't say could never happen...
The first time I said "likely never" this time I said "could happen". Meant the same thing, just different wording.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
Thanks, Dr. Masters!

Glad to hear you had a nice time in New England.
We wouldn't want you to miss the tropics,
so we had all that heat brought in just for you. LOL!
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I believe Tropical Storm Bonnie will form from the Central African wave if something else doesn't. I still highly believe we will see Colin by August 1st.
Member Since: July 6, 2010 Posts: 108 Comments: 30251
2344. xcool



by wxman57 Pro Met .LAST TIME POSTING ITTTT
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SAL appears not to be an inhibiting factor.
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2341. Dakster
Quoting MiamiHurricanes09:
LOL, It could happen. We just need a very particularly set-up that is rarely seen in the Atlantic.


I noticed you didn't say could never happen...
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SEVERE THUNDERSTORM WARNING
GAC021-140215-
/O.NEW.KFFC.SV.W.0229.100714T0138Z-100714T0215Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
938 PM EDT TUE JUL 13 2010

THE NATIONAL WEATHER SERVICE IN PEACHTREE CITY HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
BIBB COUNTY IN CENTRAL GEORGIA

* UNTIL 1015 PM EDT

* AT 935 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
LINE OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING DESTRUCTIVE WINDS
UP TO 70 MPH. THESE STORMS WERE LOCATED ALONG A LINE EXTENDING
FROM PAYNE CITY TO 11 MILES WEST OF PAYNE CITY...OR ROUGHLY ALONG
THE BIBB...MONROE COUNTY LINE...MOVING SOUTH AT 10 MPH.

* OTHER LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO
MACON...LIZELLA...WESLEYAN...AND LAKE TOBESOFKEE.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

IN ADDITION TO DAMAGING WINDS...CONTINUOUS CLOUD TO GROUND LIGHTNING
IS OCCURRING WITH THIS STORM. MOVE INDOORS IMMEDIATELY! LIGHTNING IS
ONE OF NATURES NUMBER ONE KILLERS. REMEMBER...IF YOU CAN HEAR
THUNDER...YOU ARE CLOSE ENOUGH TO BE STRUCK BY LIGHTNING.

IF YOU SEE WIND DAMAGE...LARGE HAIL OR SIGNIFICANT FLOODING...WAIT
UNTIL THE STORM HAS PASSED...AND THEN CALL THE NATIONAL WEATHER
SERVICE TOLL FREE AT 1 8 6 6 7 6 3 4 4 6 6.

&&

LAT...LON 3268 8368 3268 8372 3273 8381 3282 8389
3285 8388 3295 8371 3288 8365 3287 8356
3281 8348 3272 8359 3267 8360 3266 8359
3266 8363
TIME...MOT...LOC 0137Z 340DEG 10KT 3291 8369 3281 8387

$$


SHEESH 70 mph winds heading towards my house. We were just under a severe t storm warning yesterday, again today! Will it ever stop?
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Quoting leo305:
Did someone say nothing in the GOM in 2010?

Um then what was Hurricane Alex?

maybe they thought the BOC is not part of the GOM. Or there is only 1 state that borders the GOM.... there's.
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2337. beell
Piece of sting/wire in the ROV tool

Link
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Quoting StormW:


Yes,
The NAM model tries to spin up something from the weather that's near the Bahamas



Awesome. Thank you sir!
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I swear this list dislikes the month of July. Ever since they first used it in 1980, only one minor tropical storm formed, Alex in July 1998. And that was only for a few days at the end of the month. It looks like 2010 may follow the pattern. Oh well, there's still 2016.
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Hi Circum...yeah, monster waves coming off Cape Verde. One of ems got to stick one of these times.
This might be The One.
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Quoting largeeyes:


slow casters....

slow....cast....ers.....cast a little slower. Ah hell, you missed it. OH well... I thought it was funny!

I think we all missed it.
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2329. Patrap
Quoting NttyGrtty:
G'Nite all...cigar calling and she says "enough" with my blogitude. Patrick, still love the Department of the Navy symbol avatar, miss Ironman II, asume he's rusty and needed a shine...


Thats the USMC Emblem..


Not the Navy.

Eagle,Globe and Anchor.

The Eagle represents the Nation,..the Anchor for Naval Service..and Globe for Worldwide Reach and service.


But thanks too.
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Quoting cirrocumulus:
Link

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2327. leo305
Did someone say nothing in the GOM in 2010?

Um then what was Hurricane Alex?
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Quoting StormW:


I take it, that's a general statement?
Yes.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
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Quoting StormW:


??????????


slow casters....

slow....cast....ers.....cast a little slower. Ah hell, you missed it. OH well... I thought it was funny!
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Community Participation:

3319 comments and 33 entries posted by all members in the last 24 hours.

You have posted 5075 entries in your own blog.

You have posted 49000 comments in all blogs
Member Since: May 21, 2006 Posts: 5089 Comments: 114051
Quoting Dakster:


Thanks for cursing us...

If we get a Typhoon Tip in the Atlantic this year...
LOL, It could happen. We just need a very particularly set-up that is rarely seen in the Atlantic.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
Quoting fldude99:
My prediction is nothing in the GOM in 2010...all these so called experts are off the mark

oh give it a rest, where did you pull that prediction from,,,, your butt, geez some people. go away and behave yourself.
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Quoting stormhank:
I just did some research on climate prediction page..and from what I read la Nina tends to produce dry n mild winters.. I know this past winter down this way was wet n cold when El Nino was present,,we even had snow here in panhandle!!!
Yes. Here's a post I wrote from last night:

"Normally the NAO phases have a more direct affect in Europe, but they also affect the climate in eastern North America. This is how it works, when the NAO is in a positive phase the Icelandic low draws to the stronger south-westerly circulation over the eastern half of the North American continent which prevents Arctic air from plunging southward. If you match this up with an La Niña you are bound to have a significantly warmer winter."

Member Since: September 2, 2009 Posts: 130 Comments: 21032
2318. xcool
gulfcoastdweller go see video
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Chicklit, Have you seen Sat24 post by StormW? It's rather impressive for a July satellite. I posted a link below.
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Quoting MiamiHurricanes09:
Typhoon Tip, if it were making landfall along the eastern U.S coastline affects will be felt from Miami to New York. Something like this will likely never be seen in the Atlantic unless we have the monsoonal type development by the Cape Verde's, similar to Alex in the Caribbean.

bro I read tips circulation would cover an area from missouri to Virginia..I cant imagine a storm of that magnatude takin a path like Katrina did..there would be watches n warnings from brownsville to miami
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2314. Dakster
Quoting MiamiHurricanes09:
Typhoon Tip, if it were making landfall along the eastern U.S coastline affects will be felt from Miami to New York. Something like this will likely never be seen in the Atlantic unless we have the monsoonal type development by the Cape Verde's, similar to Alex in the Caribbean.



Thanks for cursing us...

If we get a Typhoon Tip in the Atlantic this year...
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About JeffMasters

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.