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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Mother Nature takes a pause after Hole 3, Even par.

..She looks to be grasping for the Woods though, here on 4..
Member Since: July 3, 2005 Posts: 420 Comments: 127531
Quoting clwstmchasr:


I picked 14-8-5 and I beginning to wonder if I'm too high. I thought we would have had 2 storms by now and 3 by the end of July.


Theres a possibility of two or more Cape Verde storms before August 1. Dont quote me hurrkat...
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Quoting sirmaelstrom:


That's what I found when I googled for a solution. The problem is that I have no entries in my blog, and it also won't let me Create Blog or Add New Entry. Both just redirect back to the "show.html" page.

Mine did that too! Then for some reason it just fixed itself after I tried like a billion times. I wrote them a letter but by the time they wrote back they said that it seemed that I figured it out! I dunno. :(
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Quoting Tazmanian:



are you JFV??


If it is... then that is avatar #4 for the same person.


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506. IKE
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS, MD
300 PM EDT MON JULY 12 2010



8-14 DAY OUTLOOK FOR JUL 20 - 26 2010

THE FORECAST WEEK-2 UPPER AIR PATTERN IS VERY SIMILAR TO THE EARLIER PERIOD
ALTHOUGH THE PATTERN IS FORECAST TO BE MORE AMPLIFIED. THE ENSEMBLES ARE IN
GOOD AGREEMENT FORECASTING POSITIVE HEIGHT ANOMALIES CENTERED OVER THE MIDWEST
US. THE WEEK-2 TEMPERATURE FORECAST IS VERY SIMILAR TO THE 6-10 PERIOD BUT THE
PRECIPITATION FORECAST HAS SOME DIFFERENCES. IN THE WEEK-2 PERIOD, ENHANCED
ODDS FOR ABOVE MEDIAN PRECIPITATION ARE INDICATED IN WESTERN WASHINGTON STATE
DUE TO THE MORE AMPLIFIED FORECAST TROUGH. ENHANCED ODDS FOR ABOVE MEDIAN
PRECIPITATION ARE ALSO INDICATED FOR FLORIDA ASSOCIATED WITH A SLIGHT WEAKENING
OF THE SUBTROPICAL RIDGE OVER THE REGION. ENHANCED ODDS FOR ABOVE MEDIAN
PRECIPITATION ARE LIMITED TO THE NORTHERN PLAINS AND WESTERN GREAT LAKES
REGION. PRECIPITATION TOOLS SHOW MORE VARIABILITY ACROSS THE CORN BELT AND
MID-ATLANTIC REGION SO NEAR MEDIAN PRECIPITATION IS FAVORED FOR THOSE REGIONS.
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Quoting Tazmanian:



are you JFV??
No, that's Stormtop, he or she should be on your ignore list.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting angiest:


You need to have a blog. At that point the ignore user button will send you to a page where you can enter user names to ignore, one user per line.


That's what I found when I googled for a solution. The problem is that I have no entries in my blog, and it also won't let me Create Blog or Add New Entry. Both just redirect back to the "show.html" page.
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Quoting hurrkat05:
cyber teddy i hate to disappoint you but you will not tack a storm for the rest of july. really hostile conditions have taken over the tropics..you won't see bonnie until early to mid august...



are you JFV??
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Quoting hurrkat05:
miami you talk like theres a cat 3 out there...blog space isn't important right now nothing to track for quite a while man


ROFL
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Quoting weathermancer:
Africa looks more active than entire Atl.

Nice Ring-of-Fire convective impulse following behind wave that came off yesterday.

Hmmm....interesting! :)
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498. IKE
Quoting StormW:


There ya go IKE! For all I know, I could be high in mine, but I'm sticking to it! I mean, if I changed mine in AUG. and so on, I could always be on the money too! The thing is, to make a forecast, stick with it, and see how ya do!


Same here. I'm not changing it, but I may be way off.
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495. 7544
gem shows 2 stroms in july hold on before shooting your numbers down .
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Severe Weather is really ramping up on the East Coast and the Mid-West/South. There's 3 Severe Watches out.

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491. xcool
IKE .;)
Member Since: September 26, 2009 Posts: 2 Comments: 15620
Africa looks more active than entire Atl.

Nice Ring-of-Fire convective impulse following behind wave that came off yesterday.
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488. IKE
Quoting TropicalAnalystwx13:


Dont you think thats a little low?


I picked 13-7-4 about 4 months ago. Probably too low, I admit, but I'm sticking with it.
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Quoting Tazmanian:
i wish i was the Admin
Instead of discussing and interacting with the problem why don't you just go ahead report and ignore the problem. I just don't understand why the continuous discussion has to go on and on wasting blog space.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting CBS4:


That's quite fast, StormW! Will it be jumping over any of the others basins, before arriving at ours, beforehand?


Cant you check yourself? I really dont think its that hard...
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Quoting sirmaelstrom:
Hmmmm.....Is anybody else having problems with the Ignore User button? I've tested it a few times in the past week or so and it only redirects to my blog home page. I googled this and found that it has been suggested that you have to create a blog first before you can use the Ignore feature; however, when I try to Create Blog or Add Entry in my blog it also just redirects to my blog home page. I don't currently have any blog entries. If no one knows a solution, can anyone direct me to someone who might be able to answer this for me? The Support link at the bottom of the page is of no use here.
--Thanks in advance


You need to have a blog. At that point the ignore user button will send you to a page where you can enter user names to ignore, one user per line.
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Quoting HurricaneSwirl:


Well, ok. I dunno about you, but instead of padding myself on the pad, I pat myself on the back :)


I wasn't really sure where to go with that one. None of them needed to go on the blog, though.
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Quoting HurricaneSwirl:


It's pretty scary trust me LOL

I wonder where that "FLdewey" person went to, he has tons of scary JFV pics for some reason..

LOL
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478. 7544
our bahamma blob looks good on visable sat at this hour nhc did note it so i keep on it

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477. xcool
TropicalAnalystwx13 ;)
Member Since: September 26, 2009 Posts: 2 Comments: 15620
Quoting CBS4:


Yes, sir. For finally comprehending something, you know? It's a sensational feeling, my friend. I'm sure that you've felt it before, you know? LOL, ^_^.


Well, ok. I dunno about you, but instead of padding myself on the pad, I pat myself on the back :)
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Quoting StormGoddess:

Oh, ok....well at least it wasn't something scary. :)

That's funny, I'm not afraid of tornadoes or hurricanes, but I was worried about the shower curtain. LMAO
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Hmmmm.....Is anybody else having problems with the Ignore User button? I've tested it a few times in the past week or so and it only redirects to my blog home page. I googled this and found that it has been suggested that you have to create a blog first before you can use the Ignore feature; however, when I try to Create Blog or Add Entry in my blog it also just redirects to my blog home page. I don't currently have any blog entries. If no one knows a solution, can anyone direct me to someone who might be able to answer this for me? The Support link at the bottom of the page is of no use here.
--Thanks in advance
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Quoting xcool:
i;m flollow IKE FORECAST 13 NAMED STORMS . ;) LOL


Dont you think thats a little low?
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Quoting StormGoddess:

Oh, ok....well at least it wasn't something scary. :)


It's pretty scary trust me LOL

I wonder where that "FLdewey" person went to, he has tons of scary JFV pics for some reason..
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We really need a storm to track..
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FYI, a lot of pple are getting [-] for OT discusssion.
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468. xcool
i;m flollow IKE FORECAST 13 NAMED STORMS . ;) LOL
Member Since: September 26, 2009 Posts: 2 Comments: 15620
Quoting HurricaneSwirl:


Yeah, kinda a dumb blog fad. But you should've seen the first pic. IIRC it was JFV in sunglasses trying to look bad with smiley fish in the background XD

Oh, ok....well at least it wasn't something scary. :)
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Quoting Ameister12:
CMC develops a storm in the western Caribbean. Could be another Alex like storm.
Link


Yeah it shows it farther north in the 00z run. But you're probably right in more of a southern track. The 12z EURO shows a not very developed system going Alex's track at the same time. Looks like something may be happening just don't know what.

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Quoting reedzone:


I was being sarcastic, I am predicting 15-18 named storms.


Oh NO! I had my sarcasm detector switched to the 'off' position... :-)
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About

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