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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GFS shows a huge stacked closed 600 Decimeter HP sitting off the African coast in about 7 days. The SAL is going to get a little stronger. In about 10 days it shows the HP weaken and the E Atlantic being dominated by more of a LP in the upper atmosphere. The winds coming off Africa won't be as strong then. If that pans out then some of the waves might have a better chance of developing. I wouldn't expect a named storm for quite a while with all the dry stable air in the Atlantic. the only area for development will have to be a homegrown system or possibly in the Caribbean.
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1862. IKE
Quoting scott39:
Are we not suppossed to see anything Ike?


You mean developing or your link doesn't work?
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1861. IKE
Quoting sky1989:I am not very good at reading these models, but from my understanding it looks like the ECMWF develops nothing over the next 10 days?</em>


I see a weak area of low pressure east of the islands at 144 hours. Maybe it's 1010 mb's or 1008mb's. Then it heads WNW...weakens and dies within 2 days.

Yeah...to answer your question...yes....little to nothing on that run...both of them.
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1860. scott39
Quoting IKE:
12Z ECMWF through July 23rd.

Eastern ATL view....
Are we not suppossed to see anything Ike?
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1859. sky1989
Quoting IKE:
12Z ECMWF through July 23rd.

Eastern ATL view....


I am not very good at reading these models, but from my understanding it looks like the ECMWF develops nothing over the next 10 days?
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Quoting AllStar17:
Another active Severe Weather day. Now 4 watch boxes in effect, including 1 tornado watch:



What KMZ file is this?
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Jase, suggestion: press [enter] after putting in ur link but before u start typing so ur text goes under instead of being attached 2 the side like that....
Member Since: October 25, 2005 Posts: 19 Comments: 21899
1854. IKE
12Z ECMWF through July 23rd.

Eastern ATL view....
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Hi, y'all

reading back...

reading back...

reading back...

Quoting LightningCharmer:
Good Afternoon.

I know, I'm probably will disrupt, offend or irritate some. The reason that I don't post as much as I used to is all this babble about global climate without relating it to tropical weather. I actually don't mind some repeating observations, collected data, etc. but resent those here drawing conclusions from in my opinion insufficient data. Then on the other hand, I guess it's not any better than the guess-casting that is frequently thrown about on this blog with reference to tropical weather. Being educated in the sciences has made me less interested in some of the dialog here other for mere entertainment purposes.

'Not trying to sound elitest, on the contrary, drawing conclusions from insufficient data, and claiming it as fact, and then calling those who don't share their claims "deniers" or other derogatory names is elitest and unscientific.

I view this blog and occassionally post with questions and comments mainly to obtain advance warning on possible tropical development because I live and work in south Florida. I admit, I also read this blog for entertainment because some here have an excellent sense of humor.

I guess, I may consider this my first rant here but just am genuinely concerned science of late has become much too politicized, and I fear the consequences in some cases grave.

Bravo!
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AOI

AOI

AOI

AOI

TS BUSTED FORECAST ALIBI
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may be this some day time heating but some in too keep a eye on





wind shear is this about 0

Member Since: May 21, 2006 Posts: 5091 Comments: 114956
Another active Severe Weather day. Now 4 watch boxes in effect, including 1 tornado watch:

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Absolutely no rainfall associated w/ the Nrn end of this behemoth....
Member Since: October 25, 2005 Posts: 19 Comments: 21899
Quoting CaribbeanIslandStorm:

Maybe, i think it's still too soon, we will see how it does a few hundred miles from now!!

I kind of hope your right though, we would have something too watch
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I dig the new avatar Patrap
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Quoting jasoniscoolman2010x:
maybe invest 97L SOON.

Maybe, i think it's still too soon, we will see how it does a few hundred miles from now!!
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1833 IslandsWeatherInc "No hurricanes at all, when are we going to see Bonnie?"

When Bonnie comes over the ocean, when Bonnie comes over the sea,
When Bonnie spins over the ocean, then we'll know if hurricane she'll be.
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1840. Ossqss
Quoting StSimonsIslandGAGuy:
Ossqss, Roy Spencer is a crank who believes the world is 6,000 years old, and gets hundreds of thousands of dollars from Exxon. He's not credible.


LoL, Considering his write up mirrored to some degree the NASA article, they must be cranks too. Gheeze!

Global warming: Interview with John Christy--Models, sensitivity, the PNAS paper and more
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1839. HadesGodWyvern (Mod)
Japan Meteorological Agency
Tropical Cyclone Advisory #15
SEVERE TROPICAL STORM CONSON (T1002)
3:00 AM JST July 14 2010
============================

SUBJECT: Category Two Typhoon Overland the Philippines

At 18:00 PM UTC, Severe Tropical Storm Conson (990 hPa) located at 14.8N 121.3E has 10 minute sustained winds of 50 knots with gusts of 70 knots. The cyclone is reported as moving west at 10 knots.

Storm Force Winds
=================
70 NM from the center

Gale Force Winds
=================
150 NM from the center

Forecast and Intensity
========================
24 HRS: 17.2N 117.0E - 60 knots (CAT 2/Severe Tropical Storm)
48 HRS: 19.4N 114.1E - 70 knots (CAT 3/Strong Typhoon)
72 HRS: 21.1N 111.4E - 75 knots (CAT 3/Strong Typhoon)
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Welcome back Senior Chief...
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ITCZ AXIS IS CENTERED ALONG 12N15W 10N25W 11N35W 8N42W 10N53W
8N60W.

Only one point on ITCZ axis is below 10N now... and the wave currently exiting the African coast had a low analysed near the Senegal - Mauritania border...
Member Since: October 25, 2005 Posts: 19 Comments: 21899
1836. angiest
Quoting Tazmanian:




well see it when we see it


Truer words were never spoken.
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Good afternoon.
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Quoting IslandsWeatherInc:
No hurricanes at all, when are we going to see Bonnie?




well see it when we see it
Member Since: May 21, 2006 Posts: 5091 Comments: 114956
Patrap I think what saved us was Dennis moved through fast, hit in the afternoon and was gone by 6 pm. Ivan on the other hand was moving slow and howled all night long! Just glad we were a little further away from the landfall of that bad boy!
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1830. JRRP
SAL forecast
Link
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1828. Skyepony (Mod)
Quoting FLdewey:
Since it was posted erroneously last week that the tar balls found on Cocoa Beach were from the Deepwater Horizon clusterf... uhh disaster I thought I would post the article confirming they were not from that spill.

FL Today Article



I was kinda hoping it was from the shrimper that went down off the coast. Not good it was found to be the same that hit the Keys as it came through the gulf current, chances of the gulf mess ending in the current at some point are pretty good. Outside chance it was off a boat leaking along the way for a straw of hope.
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The tropical wave at 50 is what the CMC is spinning up this weekend. I am not sure that is gonna happen as it needs to gain some latitude before running in to south america first. However, I do see some turning in that wave.
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1810 WatchingThisOne "Why aren't they waiting to get pressure readings at depth from relief well before they do the pressure test above?"

Coverup, cuz waiting would also mean collecting more crude at the surface... which would incidentally tell the public how much crude the DeepwaterHorizon has actually dumped into the Gulf, instead of the large-range of estimates that we've been receiving.
And BP prefers to risk creating an unsealable sub-seabed rupture (rendering the wellhead useless) in hopes that a total cloture will succeed, before making and being forced to publicly release such precise measurements
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Quoting TropicalAnalystwx13:


The problem is though, new outbreaks of SAL will keep coming off like seen in this 5-day java movie. When the high weakens, SAL should really decrease, and I highly believe we will get to Colin by August 1st.


What happened to Bonnie?
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Quoting TropicalAnalystwx13:


The area of thunderstorms about to emerge off Africa is a tropical wave.
Ayuh... so trying to figure out what happened 2 the WX analysis map... lol
Member Since: October 25, 2005 Posts: 19 Comments: 21899
Quoting ElConando:
Remember the power of Hurricane's and go to safety of a shelter or leave the area well before the storm approaches.







He wasnt in an evac zone.

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Quoting BahaHurican:


Now look at this ....



So is that feature just supposed to be daytime heating? There was a wave and a low analysed for it earlier today....


The area of thunderstorms about to emerge off Africa is a tropical wave.
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Now look at this ....



So is that feature just supposed to be daytime heating? There was a wave and a low analysed for it earlier today....
Member Since: October 25, 2005 Posts: 19 Comments: 21899
1814. Patrap
Quoting 69Viking:
1799. Patrap

Good day everyone, mighty quiet out there and that is a good thing! I remember Dennis all too well as the Eastern side of the storm hit my newly built less than two month old home less than 150 yards from the water! Thankfully it was built after Ivan and built up to the new code and raised off the ground 5 feet, the only damage was a few missing shingles and about 20 inches of water in the garage. The garage water wasn't a problem since the garage walls are cinder block for the first 5 feet, just had to pressure wash all the muck out of it when the water receded. Rode out the storm on higher ground at a friend's house and it was kind of scary wading to the house after Dennis passed in waste deep water to check on it but a huge relief when I saw the water line on step 3 out of 8! So far no 2005 rate of storms this year and quiet at least for the next week by the looks of it, yes that's a good thing in my books!


Watched Dennis Tops from NOLA as she went n.

Was a Bad un for sure.

That surge stopped just in time for ya seems.

A "Phew" moment Im sure
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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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