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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Quoting KoritheMan:


Arlene.


Yeppers...the first named storm for next year.
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Quoting CybrTeddy:
Intensity doesn't matter when it comes to retiring storms. In some cases, nor does damages and death totals. Hurricane Gordon in 1994 killed 1,000 people, wasn't retired.


The criteria for retirement seems quite arbitrary. Honestly, I think they need to implement an objective standard as to what actually merits retiring each storm. And if that standard is met, then retire it. And if it isn't, then don't.
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Uh-oh! It's Grothar! LOL.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
1111. beell
RE: Alex Retirement:

From the Doc's blog. Post-Alex, July 2nd.

It is possible Alex will have its named retired, though I think it unlikely. One of the countries substantially affected by a hurricane must make a request to the World Meteorological Organization (WMO) to have the hurricane's name required. Mexico was the country most affected by Alex, and Mexico has been reluctant to make retirement requests in the past. For example, Mexico suffered two landfalls from Category 5 Hurricane Emily in 2005, yet did not request that Emily's name be retired; there will be a new storm named Emily next year.
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Intensity doesn't matter when it comes to retiring storms. In some cases, nor does damages and death totals. Hurricane Gordon in 1994 killed 1,000+ people, wasn't retired.
Member Since: July 8, 2005 Posts: 259 Comments: 23605
Quoting GeoffreyWPB:
I don’t believe Alex will be retired. On another note ,a little trivia, what is the most used name for a tropical storm or hurricane?


Arlene.
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Look at this..
Looks like a perfect little eye..
not to get excited about I don't think but cool none the less

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Hi Grothar...What are you doing up past your bedtime?
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Quoting will45:


They really work i just loooked back and unless i missed one all of you know whos post have been removed.



yup it was all JFV post
Member Since: May 21, 2006 Posts: 5091 Comments: 114758
Austin Tx Weather: The simple version is that sub-tropical air masses are influenced by cooler weather fronts and systems from the northern latitudes. Did you see the good post on the floods early in the century near San Antonio?
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1103. will45
Quoting MiamiHurricanes09:
Here we go...! Let's get those "" ready!


They really work i just loooked back and unless i missed one all of you know whos post have been removed.
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Quoting CybrTeddy:


The damage estimates aren't done yet. Alex likely killed 50 people and 5 billion in damages. If that's the case Alex will probably be retired.


If that ends up being the case, then I'll consider it a candidate for retirement. My own criteria, however, is very strict.
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Quoting AustinTXWeather:
Hi all! Nice to see D.r Masters is back. Can anyone tell me what makes a system "sub-tropical"?
A subtropical cyclone is a weather system that has some characteristics of a tropical and an extratropical cyclone. As early as the 1950s, meteorologists were unclear whether they should be characterized as tropical or extratropical cyclones. They were officially recognized by the National Hurricane Center in 1972. Subtropical cyclones began to receive names off the official tropical cyclone lists in the Atlantic Hurricane Basin and the southwest Indian ocean.

There are two definitions currently used for subtropical cyclones. Across the north Atlantic and southwest Indian ocean, they require central convection fairly near the center and a warming core in the mid-levels of the troposphere. Across the eastern half of the northern Pacific, they require a mid-tropospheric cyclone to cut off from the main belt of the westerlies and only a weak surface circulation. Subtropical cyclones have broad wind patterns with maximum sustained winds located farther from the center than typical tropical cyclones, and have no weather fronts linked into their center.

Since they form from initially extratropical cyclones which have colder temperatures aloft than normally found in the tropics, the sea surface temperatures required for their formation are lower than the tropical cyclone threshold by 3°C (5°F), lying around 23 °C (73 °F). This also means that subtropical cyclones are more likely to form outside the traditional bounds of the hurricane season.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
I don’t believe Alex will be retired. On another note ,a little trivia, what is the most used name for a tropical storm or hurricane?
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1098. Grothar
Quoting CosmicEvents:
That's my line!


I think the movie from which your avatar was taken, didn't mention badges, did it??? Great movie!
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Quoting all4hurricanes:
No politics I don't care who's bashing or who's fault it is I started a nice discussion about Alex join that if you like
We'll see Alex's total damages at the end of the season I'm thinking they might top 2 billion but I also believe there is a good chance Mexico won't suggest retirement.


And I don't personally think that they should. Obviously, that's going to sound controversial to some, but I'm not going to hold back.
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Quoting AustinTXWeather:
Hi all! Nice to see D.r Masters is back. Can anyone tell me what makes a system "sub-tropical"?



sure thing when it has 2 eyes a nos and it can talk
Member Since: May 21, 2006 Posts: 5091 Comments: 114758
It's starting to look like a classic Cape Verde season. The waves coming off of Africa are almost primed and ready to go.
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Quoting KoritheMan:


I second that.



1. Possibly.

2. Doubtful.


The damage estimates aren't done yet. Alex likely killed 50 people and 5 billion in damages. If that's the case Alex will probably be retired.
Member Since: July 8, 2005 Posts: 259 Comments: 23605
Hi all! Nice to see D.r Masters is back. Can anyone tell me what makes a system "sub-tropical"?
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Mexico Retires for the dead not the damage look at Emily 05 However I think Alex is still having some lasting effects on business and the damages haven't been tallied I think Alex may be able to retire off damage alone
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Wow... I may as well be playing Sudoku right now as being on the blog... less stressful...
Member Since: October 25, 2005 Posts: 19 Comments: 21516
oh i have noted that all the JFV commets are gone
Member Since: May 21, 2006 Posts: 5091 Comments: 114758
Quoting Baltimorebirds:
I'm sorry but I don't know what that means.


That's the report button lol :)
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Quoting MiamiHurricanes09:
Another prime example is Diana in 1990. Caused $151 million in damage, nowhere near the figure of Alex. Also, Diana was about 40mb weaker than Alex even though Diana's winds were at 100mph.


Diana killed almost 3 times as much people as Alex, with 139 o.o

Lili hit the U.S. Mexico doesn't retire hurricanes nearly as often. Although if those 22 missing turn out dead.. and I certainly hope not.. it may be retired.
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No politics I don't care who's bashing or who's fault it is I started a nice discussion about Alex join that if you like
We'll see Alex's total damages at the end of the season I'm thinking they might top 2 billion but I also believe there is a good chance Mexico won't suggest retirement.
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Quoting MiamiHurricanes09:
Here we go...! Let's get those "" ready!



i have noted that the # of commets have drop
Member Since: May 21, 2006 Posts: 5091 Comments: 114758
1079...sorry
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Here we go...! Let's get those "" ready!
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting Baybuddy:


I am sorry i was short tempered and regret what i said earlier. It has been a tough month. I am going to lurk until i get my head out of ...well you know.


Thanks cuz if you're a friend of bays then you got to be mad at bp...

There are a lot of p'd off people out here...

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Quoting Talleck:
So I had a question. I was reading about how the Sahara desert is spreading and Africa is in a process of desertification. I also know that dust can diminish a tropical waves chances of developing into a hurricane, I was wondering if anyone is studying the affects of desetification on tropical storm development? I'd be interested in seeing their findings

I've been looking at it a bit but not the kind of long term research it would take..
But
Besides the desert you also need a strong Azores high and strong north African Low to create the winds to get the dust out onto the ocean. So you would have to take those into account as well in any study you did.
So you would have to take the data over time and pivot/group it on the pressures, desert area and the amount of dust and compare the number and intensity of the storms to those groups over time.
It would be a good thesis project. Who's getting their masters or PHD?
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Quoting MiamiHurricanes09:
It shouldn't be upgraded to a category 3 because recon clearly did not find category 3 strength winds. The low pressure can be attributed to the large size of Alex (skater effect). And, I do think Alex will be retired. For example, Lili in 2002 caused less money in damage and killed less people but was still retired.
Another prime example is Diana in 1990. Caused $151 million in damage, nowhere near the figure of Alex. Also, Diana was about 40mb weaker than Alex even though Diana's winds were at 100mph.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting Chicklit:


Well, if I didn't get that exactly right, I'm sorry. I went to those movies (drive in) with my boy-friend-at-the-time who liked them. This is what I got from it. Clint was the good guy, rounding up the bad guys, and making the world safer for everyone who works hard and just wants to be happy to live in.


I am sorry i was short tempered and regret what i said earlier. It has been a tough month. I am going to lurk until i get my head out of ...well you know.
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Quoting FLdewey:
Badges? We ain't got no badges! We don't need no badges! I don't have to show you any stinking badges!
That's my line!
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1073. beell
.
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Quoting Chicklit:


Well, if I didn't get that exactly right, I'm sorry. I went to those movies (drive in) with my boy-friend-at-the-time who liked them. This is what I got from it. Clint was the good guy, rounding up the bad guys, and making the world safer for everyone who works hard and just wants to be happy to live in it. You know, make a living without a lot of weird stuff going on. That's it.


Actually, girl, you were right on. Clint plays Cooper who rides around seeking revenge on the bad guys who tried to lynch him and failed. He rounds them up. Move 'em out!!! yeeehaw!
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I don't like polls...No and No.
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Quoting all4hurricanes:
Poll: Who think Alex will
:Be Upgraded to a Category three in post season considering it's pressure at 1947
: Retire considering it caused over a billion dollars in damage

I believe Hurricane Alex will remain a CAT 2.

No. From my understanding, flight level winds were quite high, HOWEVER, those winds did not translate to the surface. I believe the max winds recorded at the sea surface were only 105MPH.

When the final damage totals come in, I believe there will be about $5 billion in damage, due to the outrageous flooding caused in Monterrey, MX and surrounding communities. They received 18-36" of rain in 48 hours.

I also believe Hurricane Alex's name should be retired.
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Quoting leo305:
lol there's a temperature reading of 131 in the middle of the gulf


What? Where?
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1067. gator23
.
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Just took the pup out for a nice ¾ mile walk. Nice breeze and bearable temperatures.
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1065. leo305
lol there's a temperature reading of 131 in the middle of the gulf
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Quoting all4hurricanes:
Poll: Who think Alex will
:Be Upgraded to a Category three in post season considering it's pressure at 947
: Retire considering it caused over a billion dollars in damage

sorry accidently hit quote
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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.