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 MiamiHurricanes09:
Lotsa nothin' except for the lotsa convection in the ITCZ.

thats because its hostile out there...the fish are fighting fish, the birds are fighting each other, heck, the fish are fighting the birds. Its a veritable cornucopia of hostility out there.
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Quoting ElConando:
Hope for another week of calm.


The calm before the storm... Don't you hate how the day before a hurricane hits is one of nicest days. Kinda the clue that all h-e-double L is going to break loose.
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862. Relix
How's our African wave doing?
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Quoting IKE:


One...possibly 2....lol



Funny how it predict another Alex / TD2 to form... Wouldn't be so funny if it happened though.
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Lotsa nothin' except for the lotsa convection in the ITCZ.

Member Since: September 2, 2009 Posts: 130 Comments: 21193
859. SLU




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Hope for another week of calm.
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Quoting IKE:
GFS...both runs....operational and parallel...not a whole lot through July 28th.
thank you mr modelcaster :P
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Quoting CybrTeddy:


Yea, this is already a La Nina and has been for some time. It will likely be at peak as strong as the 2007-20078 event.



or may be even stronger
Member Since: May 21, 2006 Posts: 5091 Comments: 115097
853. IKE
Climatology wins in 2010 in the ATL....

Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting Tazmanian:



any one


Yea, this is already a La Nina and has been for some time. It will likely be at peak as strong as the 2007-20078 event.
Member Since: July 8, 2005 Posts: 259 Comments: 24021
Quoting IKE:
Atlantic Remains Quiet

Jul 12, 2010 5:55 PM

We see no signs of tropical development through at least Thursday. The tropical Atlantic features 4 tropical waves three of which are embedded in at least some Saharan dust. The dry dusty air covers a good part of the Atlantic into the eastern half of the Caribbean. This is helping to suppress thunderstorm development from the eastern Caribbean on east. Given a decrease in thunderstorms tropical development will be suppressed through much of this week. A broad high level trough over the western Atlantic into the Bahamas is also exerting strong shear across parts of the southwest and south central South Atlantic. Long range computer forecast information continues to show a quiet Atlantic Basin this whole week.

By Expert Senior Meteorologist Dan Kottlowski
Quiet is good!
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hey IKE and 09 look at this


Quoting Tazmanian:
oh my by looking at this we may be heading in too a mod too strong La Nina La Nina may be come vary strong come winter if this keeps going

The latest weekly SST departures are:


Ni�o 4 -0.4�C
Ni�o 3.4 -0.8�C
Ni�o 3 -1.0�C
Ni�o1 2 -1.3�C

Member Since: May 21, 2006 Posts: 5091 Comments: 115097
848. IKE
Quoting Dakster:


How many does the CMC predict?


One...possibly 2....lol

Member Since: June 9, 2005 Posts: 23 Comments: 37858
847. IKE
Atlantic Remains Quiet

Jul 12, 2010 5:55 PM

We see no signs of tropical development through at least Thursday. The tropical Atlantic features 4 tropical waves three of which are embedded in at least some Saharan dust. The dry dusty air covers a good part of the Atlantic into the eastern half of the Caribbean. This is helping to suppress thunderstorm development from the eastern Caribbean on east. Given a decrease in thunderstorms tropical development will be suppressed through much of this week. A broad high level trough over the western Atlantic into the Bahamas is also exerting strong shear across parts of the southwest and south central South Atlantic. Long range computer forecast information continues to show a quiet Atlantic Basin this whole week.

By Expert Senior Meteorologist Dan Kottlowski
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting Bordonaro:

I lived on Long Island in the 1966-1979 time frame. I have seen TS Doria in 1972, Hurricane Belle in 1976. Weak, measly storm, yes, BUT, I gained a GREAT respect for their power, especially after witnessing at 100-105MPH wind gust in Belle. From almost calm to a roar like a jet engine, in less than 30 seconds.

My mother, father, sister & brother in law got creamed by Hurricane Gloria in 1985. They had no power for 2 weeks, major damage, winds sustained at low CAT 3, about 115MPH, as they were on the "dreaded right NE quadrant , which added 25MPH to the sustained winds. My wife gave me a blow by blow of the 3 hr conversation with her mom during Gloria, it was REAL bad.

My sister in law, in Lake Ronkonkoma, LI had several apartment complex roofs torn completely off in her complex. One landed in main swimming pool, as they described it, "It was like a bomb just went off all of a sudden". That was over 25 years ago. NY-NJ Metro had a glancing blow form Bob in the early 1990's, but nothing since then. They are way overdue.

The sad part is most folks in the Northeast & New England are sadly unprepared for ANY major TC. Not saying a CAT 5 will hit NYC, NY. However a major CAT 3 is way overdue.


Within a month or so those ssts will be above 80 F. Anything going up there will be a major event.
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Quoting IKE:
GFS...both runs....operational and parallel...not a whole lot through July 28th.


How many does the CMC predict?
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Good evening Storm.How have you been?
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Had to leave, but I'm back...
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842. IKE
GFS...both runs....operational and parallel...not a whole lot through July 28th.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Later, everybody. :)
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Could there be developement in the southwestern Carribean in about 5 days?
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When earthquakes around a volcano go "shallow" it is the depth, in reference to magma rising. The magnitude of the earthquakes are a different story.
Iceland Meteorological Office:Link
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Quoting StormW:


Yeah, right? Who would have ever thought!


:)
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Quoting Tazmanian:
oh my by looking at this we may be heading in too a mod too strong La Nina La Nina may be come vary strong come winter if this keeps going

The latest weekly SST departures are:


Ni�o 4 -0.4�C
Ni�o 3.4 -0.8�C
Ni�o 3 -1.0�C
Ni�o1 2 -1.3�C



any one
Member Since: May 21, 2006 Posts: 5091 Comments: 115097
Quoting Ztapedoc:
I'm kinda new here, but because I live in a hurricane zone I'm interested in what most ffolks think about how the season is going to go. Although most call for an "active" season, isn't it starting off a)slow and b)unusual? Isn't June and July usually where we see tropical storms/hurricanes develop in either eastern carib or GOM rather than off the coast of Africa as did Invest 93L. If the forecasts are correct, then August/September should be extremely busy - right.
Just a bit curious from the Isle of Enchantment (Puerto Rico)

Last year was a super-slow season, with either 9 or 10 Tropical Cyclones (TC's).

This season was supposed to be super slow to start, according to DR M, due to the remaining atmospheric effects from the El Nino. Well no one is 100% correct all the time on 3RDrock from the Sun!!

Well, after a 947MB CAT 2 Alex creamed NW Mexico with 105MPH winds, and up to 36" of rain, which by the way is 200% above the normal YEARLY precip for that portion of Mexico, on Jun 30, the season has only just begun!!

We have been through Invest #'s 90-96L and a TD2 that caused MAJOR flooding in the Rio Grande Valley, remember Laredo, the last bloq, a 40 ft wide river was over 1/2 mile and flooded many areas seriously.

And the fun is YET to start!!!!
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Quoting OracleDeAtlantis:
Speaking of the NAO, I wonder what affect this could have on it ... ?

If you haven't been paying attention, this rapid fire activity has been migrating rapidly eastward towards Katla, ever since the worst travel disruption in world history. It sure looks like a shared chamber to me.






Thats not good.
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Quoting StormW:


I'm still laughing!


even funnier since she's such a smart powerful woman and owns half of Hollywood by now! ;)
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Quoting OracleDeAtlantis:
Speaking of the NAO, I wonder what affect this could have on it ... ?

If you haven't been paying attention, this rapid fire activity has been migrating rapidly eastward towards Katla, ever since the worst travel disruption in world history. It sure looks like a shared chamber to me.




I have heard those quakes are very shallow, at less than Magnitude 1 on the Richter Scale, that was as of 7-9-10. Have you heard different or is there a newer article you can link too??
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Quoting StormW:


You're kidding, right?

of course.i agree with you 100%
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Quoting StormW:


Oh. Well, just wanted to clarify, I am a Tropical Meteorologist, and I don't hype. In fact, I continue to point out the different factors, in hopes to give folks who don't understand things about Tropical Cyclones, why a lot of us think this season will be hyperactive. For instance, the dust outbreak we just had...how many episodes have we seen since June 01? We have Global signals that are more favorable than 1998, and 1995, which had 14 and 19 storms, respectively. We not only have to look at the fact that we are in a La Nina, the AMO is and has been at record warmth, Wind shear for the most part has been at or below climatology, African rainfall estimates show that it should be wetter in the Sahel region down the road, the current state of the Atlantic Tripole, and you also have to take into account the cold PDO and colder SST's in much of the EPAC in relation to the Atlantic. Even in a neutral Nino pattern, or even weak El Nino, if the Atlantic is warmer in relation to that, guess where more of the heat energy is. And, the CFS has been forecasting a predominate negative NAO for Aug and Sep, everyday, for the past 3-4 months. Need I go on?

Absolutely not, I understand why this season is potentially a disasterous one. The issue that SLU started this discussion with was a criticism of people who were saying this season is a bust. Well, so many on here talk about how they need to get the word out to the folks who don't understand the intricate details of tropical meteorlogy. Yet when they themselves set the stage for hightened expectations amongst those same folks and those folks then start expressing some disbelief in this season being anything less than sensational, people like SLU bash them with a self-rightous diatribe about how bad they are for expecting lots of horrible storms and how it only takes one, and he gets commended for it by others. It just seems rather hypocritical to me.
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Quoting OracleDeAtlantis:
Speaking of the NAO, I wonder what affect this could have on it ... ?

If you haven't been paying attention, this rapid fire activity has been migrating rapidly eastward towards Katla, ever since the worst travel disruption in world history. It sure looks like a shared chamber to me.




Indeed, a "shared" magma chamber, although distant.
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Speaking of the NAO, I wonder what affect this could have on it ... ?

If you haven't been paying attention, this rapid fire activity has been migrating rapidly eastward towards Katla, ever since the worst travel disruption in world history. It sure looks like a shared chamber to me.



Member Since: Posts: Comments:
I'm kinda new here, but because I live in a hurricane zone I'm interested in what most ffolks think about how the season is going to go. Although most call for an "active" season, isn't it starting off a)slow and b)unusual? Isn't June and July usually where we see tropical storms/hurricanes develop in either eastern carib or GOM rather than off the coast of Africa as did Invest 93L. If the forecasts are correct, then August/September should be extremely busy - right.
Just a bit curious from the Isle of Enchantment (Puerto Rico)
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Quoting OracleDeAtlantis:


Well said ...

I think it's a strange twist of fate that all this oil is sitting down there in the Gulf, waiting to be spread like frosting on the cake.

What are the odds that we would be set up for the perfect hurricane season too? It's like something out of a horror movie, and I have little doubt our worst fears will soon be realized.

I pray and hope to God (Divine Power, etc) that we do NOT have any tropical activity in the GOM until the oil is cleaned up. BUT, we have already had Alex.
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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.