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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Good Afternoon,

can someone post a link to Bastardi's forecast??
Member Since: July 1, 2005 Posts: 10 Comments: 1683
SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE COLUMBIA SC
311 PM EDT MON JUL 12 2010

SCC025-057-121945-
/O.CON.KCAE.TO.W.0009.000000T0000Z-100712T1945Z/
LANCASTER SC-CHESTERFIELD SC-
311 PM EDT MON JUL 12 2010

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 345 PM EDT FOR
CHESTERFIELD AND LANCASTER COUNTIES...

AT 305 PM EDT...THE PUBLIC REPORTED A POSSIBLE TORNADO. THIS
TORNADO WAS LOCATED ON SHALLOW UNITY ROAD...SOUTHEAST AT 15 MPH.

OTHER LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO
JEFFERSON AND KERSHAW

PRECAUTIONARY/PREPAREDNESS ACTIONS...

THE SAFEST PLACE TO BE DURING A TORNADO IS IN A BASEMENT. GET UNDER A
WORKBENCH OR OTHER PIECE OF STURDY FURNITURE. IF NO BASEMENT IS
AVAILABLE...SEEK SHELTER ON THE LOWEST FLOOR OF THE BUILDING IN AN
INTERIOR HALLWAY OR ROOM SUCH AS A CLOSET. USE BLANKETS OR PILLOWS TO
COVER YOUR BODY AND ALWAYS STAY AWAY FROM WINDOWS.


REPORT LARGE HAIL...DAMAGING WINDS OR FLOODING TO YOUR COUNTY
SHERIFF...OR CALL THE NATIONAL WEATHER SERVICE TOLL FREE AT 1 877 6 3
3...6 7 7 2.

&&

LAT...LON 3461 8023 3461 8042 3451 8066 3481 8071
3481 8035
TIME...MOT...LOC 1910Z 345DEG 14KT 3469 8056

$$

LM
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MJO will be returning to our basin.

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Quoting angiest:


I believe it was removed.



nop JFV is CBS4
Member Since: May 21, 2006 Posts: 5091 Comments: 114767
Quoting IKE:


I don't know where Bastardi is coming up with upward activity the last 10 days of July. Maybe he's just trying to convince himself being he forecasts 4 named storms in July.

I don't see it...yet.
He's first a salesman and second a met. He sees nothing in the weather, but he sees that he'd like to see more sales in a slow time. So, he sees "upward activity" in the weather....to induce upward activity in his sales.
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I hope a "Firecane" hits Miami...the three kings and the (JF... )Village idiot down there...

JUST KIDDING, I never wish serious problems for anyone
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AOI

AOI

AOI

AOI

TS BUSTED FORECAST ALIBI
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402. IKE
Quoting reedzone:


Yeah, I'm finding conditions to improve more in the beginning to middle of August. Heck Alex formed in July 31 of 2004, still was a rather active season, at least for me lol. 1998 started late to, but ended up with a historical storm in the end. So, a late start doesn't say much about the season, at least in my opinion. Though this is great news for the oil cleanup.


That's what I was thinking.
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how the heck did you no my real name? JFV
Member Since: May 21, 2006 Posts: 5091 Comments: 114767
Quoting IKE:


I don't know where Bastardi is coming up with upward activity the last 10 days of July. Maybe he's just trying to convince himself being he forecasts 4 named storms in July.

I don't see it...yet.


Yeah, I'm finding conditions to improve more in the beginning to middle of August. Heck Alex formed in July 31 of 2004, still was a rather active season, at least for me lol. 1998 started late to, but ended up with a historical storm in the end. So, a late start doesn't say much about the season, at least in my opinion. Though this is great news for the oil cleanup.
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Quoting btwntx08:

yep look what he said to me on post 229


I believe it was removed.
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Quoting CBS4:
Good afternoon, David Thomas.



what the heck????
Member Since: May 21, 2006 Posts: 5091 Comments: 114767
Quoting jasoniscoolman2010x:
only get two name storm unit august 1.



TD 2 nevere got in name
Member Since: May 21, 2006 Posts: 5091 Comments: 114767
i dont think the BERMUDA HIGH has any thing too do with CV season
Member Since: May 21, 2006 Posts: 5091 Comments: 114767
389. IKE
Quoting CBS4:
Dammit, Ike! But hey, did you at least notice the synopsis pattern that it shows towards the end of it's run? A MUCH WEAKENED BERMUDA HIGH, meaning, here comes the CVseason, did you observe that, Ike? Also, there endd s the TX/MX landfalls.


I see a high that's flattening some from north to south, but is stretching back out over the northern GOM...like the NOGAPS shows happening.
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CMC develops a storm in the western Caribbean. Could be another Alex like storm.
Link
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Quoting angiest:


Is that the thing we were watching in the SW Caribbean a few days ago?

It probably was.
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Jase, just call me a blobcaster... lol
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Quoting jasoniscoolman2010x:
wind high wind shear is everywhere right now..to much dry air..no storms this week.


Pretty much, quiet for another week or so, maybe 2 weeks. This is good news :)
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Quoting stillwaiting:
this guys(mr shower curtain)problems run deeeep!!!!,I wish he'd just leave us alone:(




i no i dont think JFV under stans what the word bannd means


here i help him under stan


B-A-N-N-D
Member Since: May 21, 2006 Posts: 5091 Comments: 114767
383. IKE
Quoting reedzone:


It seems July will be mostly quiet, August, could be different. Though this is good news for those who want to still prepare for the upcoming storms in the later months.


I don't know where Bastardi is coming up with upward activity the last 10 days of July. Maybe he's just trying to convince himself being he forecasts 4 named storms in July.

I don't see it...yet.
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Quoting reedzone:


One forecast saw it coming, that is the UK MET forecast which called for about 13 storms for 2006. Now it's calling for 18-20 storms, I think they called for 10 storms last year, not sure though.


UKMET called for 6 named storms last year. Weren't too far off.
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Quoting Ameister12:

1. SHOWERS AND THUNDERSTORMS ASSOCIATED WITH A BROAD AREA OF LOW
PRESSURE ARE GRADUALLY BECOMING BETTER ORGANIZED A COUPLE HUNDRED
MILES SOUTH-SOUTHWEST OF THE GULF OF TEHUANTEPEC. ENVIRONMENTAL
CONDITIONS ARE CONDUCIVE FOR ADDITIONAL DEVELOPMENT OF THIS SYSTEM
OVER THE NEXT COUPLE OF DAYS AS IT MOVES WEST-NORTHWESTWARD AT
ABOUT 10 MPH. THERE IS A MEDIUM CHANCE...30 PERCENT...OF THIS
SYSTEM BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.



Is that the thing we were watching in the SW Caribbean a few days ago?
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this guys(mr shower curtain)problems run deeeep!!!!,I wish he'd just leave us alone:(
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OK, according to graphs on ossqss's blog, WunderBloggers are forcasting an average of 18 named storms and 10-11 hurricanes, with 6 major canes expected. Will be interesting to see how close to this average we actually get....
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Quoting IKE:



Here's the eastern Atlantic view through July 22nd...nothing.


It seems July will be mostly quiet, August, could be different. Though this is good news for those who want to still prepare for the upcoming storms in the later months.
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JFV is CBS4 he nevere no when too stop comeing on with new names i wounder if he even nos what the word banned means
Member Since: May 21, 2006 Posts: 5091 Comments: 114767
The pattern on the Eastern Atlantic satellite is rather ominous. The circulation patterns are much more organized and less chaotic than previous seasons. It looks like we are going to have an early season. Is that area around the Bahamas going to develop?
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372. IKE
Quoting CBS4:
Afternoon there, Ike! Is it showing much, sir?


Nope.

Hmmm.
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340

Baby wipes, lots of booze (self medication) and a whole house backup generator. In lieu of a whole house generator, you might consider a tri-fuel adapter kit for a portable standby unit. It allows you to run on gasoline, natural gas or propane. As long as your natureal gas line is not damaged or you have one of the honking big residental propane tanks, you can run indefiniteley.

That is a lot easier than trying to find gasoline three days after a storm if you are at ground zero.
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369. IKE
Quoting IKE:
12Z ECMWF



Here's the eastern Atlantic view through July 22nd...nothing.
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Quoting nrtiwlnvragn:


Graphs are on ossgss' blog.
Thanks, nrti.
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Quoting BahaHurican:
You know, speaking of forecast numbers for the season, didn't we do a blog forecast on ossqss' blog? Wonder what our WunderBloggers' 2010 forecast average is for NS and hurricanes?


Graphs are on ossgss' blog.
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1. SHOWERS AND THUNDERSTORMS ASSOCIATED WITH A BROAD AREA OF LOW
PRESSURE ARE GRADUALLY BECOMING BETTER ORGANIZED A COUPLE HUNDRED
MILES SOUTH-SOUTHWEST OF THE GULF OF TEHUANTEPEC. ENVIRONMENTAL
CONDITIONS ARE CONDUCIVE FOR ADDITIONAL DEVELOPMENT OF THIS SYSTEM
OVER THE NEXT COUPLE OF DAYS AS IT MOVES WEST-NORTHWESTWARD AT
ABOUT 10 MPH. THERE IS A MEDIUM CHANCE...30 PERCENT...OF THIS
SYSTEM BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

Member Since: Posts: Comments:

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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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