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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Wave coming off Africa entering into a favorable enviroment:

Member Since: July 6, 2010 Posts: 113 Comments: 32717
2062. xcool
tropical deads stuff just not add up right
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2060. DDR
Quoting stormpetrol:
11N/55W, also 10N/37W starting to look a bit interesting this evening especially 11/55, definitely a "spin" there.

Hi storm
you can bet im keeping an eye on those 2.
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Quoting RitaEvac:
Should of had another named storm by now,


If we allready had Bonnie you would be saying the same thing
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Quoting largeeyes:
I'm planning to head to Jamaica, trying to decide between early Sept. and late November/Christmas. I'm thinking I'm tempting fate to go in Sept.....


No, No! Not September!
Member Since: July 6, 2010 Posts: 113 Comments: 32717
11N/55W, also 10N/37W starting to look a bit interesting this evening especially 11/55, definitely a "spin" there.
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2055. xcool
13-5-3 lol
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Patrick, is that the Maritime Oilman's Baker's seal you're sport'n as your new avitar?
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2052. hydrus
Quoting TropicalAnalystwx13:
My numbers:

17-24 named storms

9-12 hurricanes

4-6 major hurricanes

1-3 Cat 5's
Catastrophe-Caster!!!...Or...Numerous-Stormcaster!!
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I'm planning to head to Jamaica, trying to decide between early Sept. and late November/Christmas. I'm thinking I'm tempting fate to go in Sept.....
Member Since: August 22, 2006 Posts: 0 Comments: 1462
2049. hydrus
Quoting TropicalAnalystwx13:


I would hate that! The blog would go crazy! All the downcasters would come and say: told ya it was going to be a bust.
Yes I know...Then they would start there own sect, and infiltrate the blog with there down-casting dominance. I,m scared Poncho....
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Quoting NCHurricane2009:


Darn, was about to look at the sat imagery:

http://www.nhc.noaa.gov/satellite.shtml

That website is kicking me out. "Most likely causes:
•This website requires you to log in."

Don't know what happened. Anyone else getting this on this website?

I had a hard time too, just close all your current tabs and go www.nhc.noaa.gov in the address bar.I notice this site with loops been messing up alot lately!
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Quoting NCHurricane2009:


Darn, was about to look at the sat imagery:

http://www.nhc.noaa.gov/satellite.shtml

That website is kicking me out. "Most likely causes:
•This website requires you to log in."

Don't know what happened. Anyone else getting this on this website?


Not me...worked perfectly for me.
Member Since: July 6, 2010 Posts: 113 Comments: 32717
2045. IKE
Post #2026 is from Accuweather.
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Quoting stormpetrol:
Keep an on 13N/81W if it doesn't run into Nicaragua/Honduras like the last 2 AOI. Wave about to emerge Africa could be the next thing to watch.


Darn, was about to look at the sat imagery:

http://www.nhc.noaa.gov/satellite.shtml

That website is kicking me out. "Most likely causes:
•This website requires you to log in."

Don't know what happened. Anyone else getting this on this website?
Member Since: Posts: Comments:
My numbers:

17-24 named storms

9-12 hurricanes

4-6 major hurricanes

1-3 Cat 5's
Member Since: July 6, 2010 Posts: 113 Comments: 32717
2042. hydrus
Quoting IKE:


Bust-casters!
You are on a roll IKE..I am digging it.
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2041. DDR
Good evening all
Heavy showers all day today here in Trinidad,rainfall is above average where i'm at.
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2040. xcool
ilove Bustcasters .hahaha let me stop
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Quoting hydrus:
Yeah, next thing you know they will say no more hurricanes in the Atlantic Basin for the rest of the year.....:)


I would hate that! The blog would go crazy! All the downcasters would come and say: told ya it was going to be a bust.
Member Since: July 6, 2010 Posts: 113 Comments: 32717
I'm still thinking we could get 2-3 named storms before end of July.I'm still going with 19/10/6
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2037. hydrus
Quoting btwntx08:
truly 2010 aint no bust and second i expect development early next week
And now that you posted that, we will have 10 cat-5,s....Why BTWNTX08.......Why?
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Quoting btwntx08:
truly 2010 aint no bust and second i expect development early next week


Agreed. I don't think we should call bust until mid-August at the earliest.

I'd say development sometime next week seems feasible.
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I think the buildup and anticipation for an active season over the past few months has many perplexed as to why storms aren’t popping up on a regular basis. As many have stated, August and September could be what would be considered hyper-active months.
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2034. IKE
Quoting hydrus:
Yeah, next thing you know they will say no more hurricanes in the Atlantic Basin for the rest of the year.....:)


Bust-casters!
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2032. hydrus
Quoting IKE:


Downcasters!
Yeah, next thing you know they will say no more hurricanes in the Atlantic Basin for the rest of the year.....:)
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Quoting nyhurricaneboy:
Afternoon all!

Quiet day today on the blog. That will not be the case in a few week's time. I am predicting Cape Verde development within this period, based on current trends.

Anyway, a little poll:
What will Conson's intensity be for the next advisory?
A) less than 45 mph
B) 45 mph
C) 50 mph
D) 60 mph
E) greater than 60 mph

I'm voting C.
Member Since: July 6, 2010 Posts: 113 Comments: 32717
Quoting nyhurricaneboy:
Afternoon all!

Quiet day today on the blog. That will not be the case in a few week's time. I am predicting Cape Verde development within this period, based on current trends.

Anyway, a little poll:
What will Conson's intensity be for the next advisory?
A) less than 45 mph
B) 45 mph
C) 50 mph
D) 60 mph
E) greater than 60 mph

I'm voting C.


Right now, Conson is 55 knots (65 mph). I think C-50 mph is what I am going with now too. Looks less organized after landfall and due to northeasterly shear.
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Keep an on 13N/81W if it doesn't run into Nicaragua/Honduras like the last 2 AOI. Wave about to emerge Africa could be the next thing to watch.
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2028. IKE
Quoting IKE:
No Development Expected for Several Days

Jul 13, 2010 6:04 PM

A large area of Saharan dry dusty air continues to flow across the southern North Atlantic mostly north of 13 north and as far west as the central Caribbean. We are also observing strong shear that extends from the Bahamas southeast across Hispaniola across Puerto Rico and into the southern North Atlantic. This shear is projected to remain over the northern Caribbean through at least Friday. The combination of the dry Saharan air and shear will inhibit tropical development for the next several days. The more reliable long range computer model output shows no support for tropical development through the rest of this week , through the upcoming weekend and into early next week. Based on this information we see no signs of tropical development in the Atlantic tropical basin through the rest of this week.


Downcasters!
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2026. IKE
No Development Expected for Several Days

Jul 13, 2010 6:04 PM

A large area of Saharan dry dusty air continues to flow across the southern North Atlantic mostly north of 13 north and as far west as the central Caribbean. We are also observing strong shear that extends from the Bahamas southeast across Hispaniola across Puerto Rico and into the southern North Atlantic. This shear is projected to remain over the northern Caribbean through at least Friday. The combination of the dry Saharan air and shear will inhibit tropical development for the next several days. The more reliable long range computer model output shows no support for tropical development through the rest of this week , through the upcoming weekend and into early next week. Based on this information we see no signs of tropical development in the Atlantic tropical basin through the rest of this week.
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2025. xcool
2010 bust lol
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Afternoon all!

Quiet day today on the blog. That will not be the case in a few week's time. I am predicting Cape Verde development within this period, based on current trends.

Anyway, a little poll:
What will Conson's intensity be for the next advisory?
A) less than 45 mph
B) 45 mph
C) 50 mph
D) 60 mph
E) greater than 60 mph

I'm voting C.
Member Since: Posts: Comments:
Quoting hydrus:
S.S.I.G wishing for tropical waves again huh? And I thought the 2012 doomsdayers were bad....sheesh!


A tropical wave is not bad, its the tropical cyclone that's bad. I wonder if SSIG is experiencing a developing drought, we need some rain here too in NC after a dry and hot June and early July. Anything that brings rain without severe weather is good.
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2022. hydrus
Quoting StSimonsIslandGAGuy:
I wish a tropical wave would move this way and bring me some rain.
S.S.I.G wishing for tropical waves again huh? And I thought the 2012 doomsdayers were bad....sheesh!
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Quoting RitaEvac:
Should of had another named storm by now,


If you mean this because of the predictions of the 2010 season, you have to wait and see. Some seaons produce activities in big clusters, like in 2004 when we had 0 storms till August, when 8 storms developed in that month alone. You just never know what the storm distribution month-by-month will be.

But, quieter seasons are nicer though. It gets too hectic to follow whats going on sometimes. Also, its depressing to hear about storms hitting land all the time.
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I'm here...
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Well, nobody in here, must be winter time
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Should of had another named storm by now,
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Increased moisture, thanks IKE
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2016. IKE
Quoting RitaEvac:
Whats this wave supposed to do this weekend? go into LA/TX??


SYNOPSIS FOR THE GULF OF MEXICO
430 PM CDT TUE JUL 13 2010

.SYNOPSIS...THE NORTHERN PORTION OF A TROPICAL WAVE WILL MOVE
ACROSS THE BAY OF CAMPECHE TONIGHT. WEAK RIDGE FROM S FLORIDA TO
23N93W WILL SHIFT N TO ALONG 28N WED THROUGH THU AND TO JUST N
OF THE GULF FRI AND SAT AS A TROUGH MOVES FROM E TO W ACROSS
GULF THU THROUGH SAT.
THE RIDGE WILL BUILD AGAIN FROM E TO W
ACROSS THE GULF WATERS BY SUN.
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Quoting jasoniscoolman2010x:
maybe invest 97L soon..lets see what happern to it.


That low pressure center is at a somewhat high latitude for development, its about to move into 25/26 C water, only marginal:

http://www.ssd.noaa.gov/eumet/eatl/flash-wv.html

During the animation, you can click on the SST check box to see this. In the animation, looks like the tropical wave is fighting off the SAL (saharan air layer) in this water vapor loop as well. Its not going to be easy for it to develop till it moves into warmer SSTs and has successfully not wrapped in the SAL.

Yesterday, I apoologize for saying the SAL was not really having an effect. The tropical wave that came off of Africa on July 11 has lost all non-ITCZ convection to the SAL, and the wave coming off of Africa today (July 13) may suffer the same fate. It seems the circulation of these waves ingests the SAL to their north.
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Whats this wave supposed to do this weekend? go into LA/TX??
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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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