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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2664. Motttt
not any thing that I have read
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I DID IT I DID IT



YAY YAY YAY


I DID IT I DID IT


YAY YAY YAY


4211 comments and 33 entries posted by all members in the last 24 hours.

You have posted 5076 entries in your own blog.

You have posted 50000 comments in all blogs.
Member Since: May 21, 2006 Posts: 5091 Comments: 115454
2662. xcool
quiet won't last much longer
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2661. centex
Quoting Motttt:
Looks like that oil is still coming out to me..Link
Have they reported on test yet?
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2660. xcool
40w im keep eye on
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2659. Motttt
Looks like that oil is still coming out to me..Link
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2658. JLPR2
Quoting CyclonicVoyage:


All due respect but, 2010 kicked off on June, 25th and finished off Hurricane style. Surely not a late start.


Yes of course, we already had Alex and Td2, I guess the starting late idea is just a figure of speech, as in, when we start tracking and dont stop. XD

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that wave is going to become our first CV TC this year IMO,been watching it for 48hrs now....
Member Since: October 5, 2007 Posts: 20 Comments: 4970
Quoting xcool:
that so crazy 1998 and 2010 same list of names


While we're talking about 2004, that also had the same naming list (obviously, this is different now. Colin, Fiona, Igor, and Julia replaced Charley, Frances, Ivan, and Jeanne)
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2655. xcool
that so crazy 1998 and 2010 same list of names
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Quoting JLPR2:


2004 was an El Niño year so it doesn't work as an analog, I'm thinking more of 1998, which started late too


All due respect but, 2010 kicked off on June, 25th and finished off Hurricane style. Surely not a late start.
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2653. centex
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Quoting earthlydragonfly:
Quoting Jeff9641:
Latest GFS carries almost every wave to FL over the next 16 days. This pattern is not looking good. Could be a 2004 type set up in the cards if this pattern holds. If you don't think so then just look at the models on FSU's site.

Jeff,
Do you have a link to the FSU site?


I think this is what he's referring to.
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Quoting JLPR2:


2004 was an El Niño year so it doesn't work as an analog, I'm thinking more of 1998, which started late too


I'm thinking 1998 as well.
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2650. xcool
ha
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2649. xcool
wave by af cost :0
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2648. JLPR2
Quoting xcool:
JLPR2 that good analog year!!!!!


yep, funny thing is it had the same list of names this year has XD
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2647. JLPR2
Well, this is kinda interesting, the new TW is developing convection, the spin is lost to the SAL, but convection is forming over water.

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2646. xcool


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2645. xcool
JLPR2 that good analog year!!!!!
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2644. centex
40W only area of interest.

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2643. JLPR2
Quoting xcool:
i think best 1969 2004analog year!!!!! imo


2004 was an El Niño year so it doesn't work as an analog, I'm thinking more of 1998, which started late too
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Quoting xcool:
i think best 1969 2004analog year!!!!! imo


With the quick onset of La Nina, I am thinking 15/8/4. It used to be 7 but, Alex was a surprise.
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i this got a e mail from keep and he said he been lock up
Member Since: May 21, 2006 Posts: 5091 Comments: 115454
2640. xcool
i think best 1969 2004analog year!!!!! imo
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2639. xcool
tkeith oh cool
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2638. tkeith
Quoting xcool:
tkeith .yeah slidell la.not yet
I'm in Kenner now. I helped build that bridge. We started building it in May 2005...Got Delayed in late August.
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Quoting xcool:
2010 Not like 2005...

Watching TWC this morning and their new tropical guy(Dr. Rick Knabb) mentioned that back in the Katrina summer of 2005, we already had 5 named storms with 3 of them reaching hurricane force. So far in 2010 we have had one Hurricane. Does that tell us anything? Not really, unless this current quiet trend lasts well into August. Even then, the heart of the season for us is August & September...plenty of time for 12-15 storms to form. Still, I'm encouraged by this current quiet trend, but we all know it won't last.

Currently we have an upper high building across the northern Gulf which should limit our shower chances for the next 2-3 days. A tropical wave will increase moisture and shower chances by Friday thru the weekend.
Posted by Bob Breck


Actually, one of the analog years from CSU, 1969, didn't start until July, 25th and finished out with 18 named storms.
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2636. centex
Our 40W wave seems to be our best AOI.
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2635. xcool
tkeith .yeah slidell la.not yet
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2634. tkeith
xcool...you in Slidell?

I lived there for about 2-1/2 years. You ever been to the Rigolets Pass Bridge?
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Quoting FLdewey:
Nothing you can do... Besides 2012 is next year get your doom forecast right. :P


Unless your going against the masses, 14 to 27 storms are forecast to come around the way, no doom, just riding the bandwagon. My wife is a Psychology major in case your in denial?
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2632. xcool
2010 Not like 2005...

Watching TWC this morning and their new tropical guy(Dr. Rick Knabb) mentioned that back in the Katrina summer of 2005, we already had 5 named storms with 3 of them reaching hurricane force. So far in 2010 we have had one Hurricane. Does that tell us anything? Not really, unless this current quiet trend lasts well into August. Even then, the heart of the season for us is August & September...plenty of time for 12-15 storms to form. Still, I'm encouraged by this current quiet trend, but we all know it won't last.

Currently we have an upper high building across the northern Gulf which should limit our shower chances for the next 2-3 days. A tropical wave will increase moisture and shower chances by Friday thru the weekend.
Posted by Bob Breck
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Quoting JRRP:



(Shrugs Shoulders) What are ya gonna do? That freaking high is going to tell ya, it's gonna be nasty this year.
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Quoting FLdewey:


LMAO... "at least" one cat 5 eh?

What say you Kirk?

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Kirk says FAIL.


yes,my forecast is 19-12-7-3(cat5) and with this pattern...
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2627. SLU
Here comes tropical wave #26 for 2010. The NHC has added it to the surface chart.
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2626. xcool



MMM


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Hi all,
Just checking in. I see the Doc never posted an update. I assume that's due to nothing interesting going on and not something wrong?
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2624. will45
Quoting earthlydragonfly:
Quoting Jeff9641:
Latest GFS carries almost every wave to FL over the next 16 days. This pattern is not looking good. Could be a 2004 type set up in the cards if this pattern holds. If you don't think so then just look at the models on FSU's site.

Jeff,
Do you have a link to the FSU site?



Link

it doesnt develope anything just waves.
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2623. DirtDan
Quoting Drakoen:


Elaborate



There's alot more there than just the normal V Sig.... Lots of vorticity with that wave. It looks quite promising. Sheer is the only thing that could kill it.
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2622. Ossqss
Quoting Drakoen:


No, but when we see waves coming off with spins consecutively then we should be concerned with the potential for something further down the road; the MIMIC-TPW we are seeing classic for EATL development, perhaps signs of an early Cape Verde season.


Good point, but are we actually seeing more energy involved as compensation for the delta in temps we have had last winter and the same currently in the Southern hemisphere? Balancing if you will... on a larger scale.

The activity over the African continent has certainly picked up recently. I still wonder about the Gulf of Guinea factor on SAL ,,, ......

L8R

WPAC wow ! Clickable pic --



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2621. xcool
GO TO PAGE 52
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2620. JLPR2
The spin with the last one exited too far north, a little more to the south and it would be in better conditions.

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2619. JRRP

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Quoting Jeff9641:
Latest GFS carries almost every wave to FL over the next 16 days. This pattern is not looking good. Could be a 2004 type set up in the cards if this pattern holds. If you don't think so then just look at the models on FSU's site.

Jeff,
Do you have a link to the FSU site?
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Just got on... what's happening?

Last I left here, a bunch of nothing, except some very nice waves coming off Africa....
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2616. xcool
HMM
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Quoting Jeff9641:
Latest GFS carries almost every wave to FL over the next 16 days. This pattern is not looking good. Could be a 2004 type set up in the cards if this pattern holds. If you don't think so then just look at the models on FSU's site.


Not good.FL will see at least one cat5 hurricane.I give a 85% chance for this
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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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