More pre-season predictions of a very active Atlantic hurricane season

By: Dr. Jeff Masters , 3:02 PM GMT on July 12, 2010

Share this Blog
5
+

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

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 2264 - 2214

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57 | 58 | 59 | 60 | 61Blog Index

2263. Dakster
Stormw - You are in rare form tonight... I guess the slow tropics brings out another side of you.
Member Since: March 10, 2006 Posts: 0 Comments: 10799
bump
Member Since: May 21, 2006 Posts: 5091 Comments: 115455
Quoting Skyepony:
It's Firefox.. I can't see NOAA satellite & SSD page (forbidden) in Firefox but I can in IE...

I can't see on IE but I just switched to GoogleChrome and no problems at all
Member Since: Posts: Comments:
Problems may be related to


ALERT ADMINISTRATIVE MESSAGE
NATIONAL WEATHER SERVICE SOUTHERN REGION HEADQUARTERS
725 PM CDT TUE JUL 13 2010

TO: ALL SOUTHERN REGION OFFICES

FROM: REGIONAL OPERATIONS CENTER

SUBJECT: NETWORK PROBLEMS

SOUTHERN REGION HEADQUARTERS IS STILL WORKING TO CORRECT A PROBLEM
WITH THE NETWORK. THE ISSUE APPEARS TO BE WITH THE DNS WHICH
NOT ALLOWING EXTERNAL USERS ACCESS TO THE SOUTHERN REGION WEB SITE.
SOUTHERN REGION PERSONNEL WILL CONTINUE TO WORK TO CORRECT THIS
ISSUE AND WILL KEEP YOU UPDATED AS NEW INFORMATION BECOMES
AVAILABLE. THANKS FOR YOUR PATIENCE.

Member Since: Posts: Comments:
2257. Dakster
Quoting Patrap:
Its a NOAA server issue.

The sky aint falling.

Enjoy the nice weather .

Calamity will arrive soon nuff.

Restock the Fresca's maybe


So true... Only I like Dr. Pepper better.
Member Since: March 10, 2006 Posts: 0 Comments: 10799
2256. Grothar
Hey, MiamiHurricane09; :P

Member Since: Posts: Comments:
2255. Patrap
It aint FireFox skye.


as its fine in 3.0 and 3.6.6
Member Since: July 3, 2005 Posts: 428 Comments: 129902
StormW: The intensity of the SAL layer has decreased gradually over the last five days. The moisture from several waves eroded it somewhat.
Member Since: Posts: Comments:
2253. Skyepony (Mod)
It's Firefox.. I can't see NOAA satellite & SSD page (forbidden) in Firefox but I can in IE...
Member Since: Posts: Comments:
2252. marmark
"The 2009 forecast called for 11.5 named storms"...What is 1/2 a storm...Bon? hehe or is that a half-caster?
Member Since: Posts: Comments:
2250. Patrap
Its a NOAA server issue.

The sky aint falling.

Enjoy the nice weather .

Calamity will arrive soon nuff.

Restock the Fresca's maybe
Member Since: July 3, 2005 Posts: 428 Comments: 129902
There is quite a bit less SAL around the ITCZ than five days ago. There could be some development in a couple of days.
Member Since: Posts: Comments:
now the pic are out now I was looking at the surface analsys I reloaded it now I get

Forbidden

You don't have permission to access /tafb_latest/WATL_latest.gif on this server

This is getting on my nerves now
Member Since: Posts: Comments:
2246. Grothar
Quoting KoritheMan:


It won't let me use of any of their satellite products, actually. All I was able to view was the TWO and TWD, and even then, with struggles. Ugh.


The NOAA satellite site had trouble with their server a while ago. Some could access it and some could not. It seems to be still having a little trouble, but better than a few hours ago.
Member Since: Posts: Comments:
hey KoritheMan same here the only difference is that it happens with most of the noaa sites for me
Member Since: Posts: Comments:
2243. SLU
Quoting SunnyDaysFla:
Thanks SLU


anytime ..
Member Since: July 13, 2006 Posts: 13 Comments: 5367
2242. bakers
remember, it is not the total number of cyclones that is important, but the number of landfalling cyclones that is. only six may form, but if all hit land that is a bad year.
Member Since: Posts: Comments:
2241. Patrap
All NOAA Floater Imagery
Member Since: July 3, 2005 Posts: 428 Comments: 129902
Thanks SLU
Member Since: Posts: Comments:
Quoting KoritheMan:
Is anyone else having trouble browsing the NHC site? It won't let me activate very many of their products without saying I need permission to do so.


Almost everyone, I think someone said you had to exit all tabs...
Member Since: Posts: Comments:
2238. beell
Quoting KoritheMan:
Is anyone else having trouble browsing the NHC site? It won't let me activate very many of their products without saying I need permission to do so.


Intermittant trouble with the SSD loops.
They have been pretty glitchy this season.
Member Since: Posts: Comments:
2237. Patrap
Conson rainbow Image

Member Since: July 3, 2005 Posts: 428 Comments: 129902
2236. SLU


There you go

It's the classical appearance of tropical waves in the Atlantic. At the apex of the inverted V lies the axis of the wave.
Member Since: July 13, 2006 Posts: 13 Comments: 5367
I’m having no problems accessing any part of the NHC site.
Member Since: Posts: Comments:
Quoting MiamiHurricanes09:
Same here. I can use any of the satellite images.


It won't let me use of any of their satellite products, actually. All I was able to view was the TWO and TWD, and even then, with struggles. Ugh.
Member Since: Posts: Comments:
2233. Patrap
..."Caught in a Bad Invest"..
Member Since: July 3, 2005 Posts: 428 Comments: 129902
2232. tkeith
Quoting beell:
"It's dead. Jim"-caster.

There ya go talkin about tropical weather again Beell...
Member Since: November 1, 2004 Posts: 25 Comments: 8937
Thanks StormW

Taz---that devil really should be your avatar
Member Since: Posts: Comments:
2230. Dakster
Quoting TropicalAnalystwx13:
I know one that hasn't been used before!

Forecaster!!!!


ROFLMAO!!
Member Since: March 10, 2006 Posts: 0 Comments: 10799
Blog Update!

July 13, 2010 - 7:20 PM EDT - Tropical Update - 7 Day Forecast


Be back later.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting KoritheMan:
Is anyone else having trouble browsing the NHC site? It won't let me activate very many of their products without saying I need permission to do so.
Same here. I can't use any of the satellite images.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
2225. KEEPEROFTHEGATE (Mod)
Quoting Tazmanian:


now oh would be a commet caster



heh heh heh



dont look at me am a good little boy

Member Since: Posts: Comments:
Is anyone else having trouble browsing the NHC site? It won't let me activate very many of their products without saying I need permission to do so.
Member Since: Posts: Comments:
2223. tkeith
Quoting TropicalAnalystwx13:
I know one that hasn't been used before!

Forecaster!!!!
this is not a golf blog...
:)
Member Since: November 1, 2004 Posts: 25 Comments: 8937
And an inverted"V" means what? Sorry but that's a new one for me!
Member Since: Posts: Comments:
I know one that hasn't been used before!

Forecaster!!!!
Member Since: Posts: Comments:
2218. xcool
LOL
Member Since: Posts: Comments:
2217. tkeith
Quoting FLdewey:


NO NEW TAXES!
taxcaster...
Member Since: November 1, 2004 Posts: 25 Comments: 8937
2216. xcool
FLdewey .2201.
Member Since: Posts: Comments:
If we couldn't laugh,
we would all go insane


BP North America
Moderator: Daren Beaudo
07-13-10/2:30 p.m. CT
Confirmation # 87627158
Page 3


"Now, as I said this test is not straight - we have got all of our scientists and we've got all the government scientists working together, paying attention to the way this is and they will collectively help make these decisions as we move along and of course, Admiral Allen is the national (innocent) commander of this."


http://www.bp.com/liveassets/bp_internet/globalbp/globalbp_uk_english/incident_response/STAGING/loc al_assets/downloads_pdfs/BPtranscript_tech_briefing07132010_330PMCST.pdf
Member Since: Posts: Comments:

Viewing: 2264 - 2214

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57 | 58 | 59 | 60 | 61Blog Index

Top of Page

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.

Local Weather

Overcast
37 °F
Overcast

JeffMasters's Recent Photos

Lake Effort Snow Shower Over Windsor, Ontario
Sunset on Dunham Lake
Pictured Rocks Sunset
Sunset on Lake Huron