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

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

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


The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Reader Comments

Currently conditions are showing no tropical development. When conditions change I feel the tropics will be very active for August and Sept. BP has halted all work in the gulf, they have had time and the tropics have behaved for them so far, this will not last much longer.
3002. Patrap
Record Events for Fri Jul 23, 2010 through Thu Jul 29, 2010

Total Records: 3060

Rainfall: 807

High Temperatures: 453

Low Temperatures: 71

Lowest Max Temperatures: 222

Highest Min Temperatures: 1507
3003. Patrap


3004. Patrap


3006. Patrap
From WWL TV NOLA this Morning.

3007. Patrap
3011. Patrap
As StormJunkie and portlight assessed the situation in N. Carolina,,,we came acrooss this Older woman who can use a hand from us.

Presslord just got off the phone with this kinds soul and she was in tears over hearing were gonna help here.

So I ask everyone to consider helping us help her.

We can change Lives for the better,,and thats what were gonna do here.

Cuz we can.

Dayle White is a widow from Jacksonville, NC, who lost about 60% of her belongings and her landlord is unsure when or if she'll be able to return to her home. Her renters' insurance (Nationwide) is denying her coverage due to lack of flood coverage. She is on a limited fixed income. She is in need of a place to live...as well as clothes and furniture. We want to help her get another apartment, as well as some clothing and furniture. She is particularly upset over the loss of her recliner chair, which was destroyed.

Please help as you can. And know that Ms. White will be grateful.

We are identifying others in need and will post their stories as things come into focus.

3012. Patrap
The following is an open letter from Richard Lumarque, the extraordinary man who headed up our field team in Haiti after the earthquake in January. For those of you who followed our efforts in the aftermath of the earthquake you will remember the amazing job that Richard, his cousin Tabitha and their team did in the early days; they worked miracles and without them we would have accomplished a mere fraction of what we did.

Portlight Featured Wunderground Entry

Richard in Haiti earlier this year doing the Best of Works..

Help us Bring some Joy to those without much this season..


Dear Paul,

I want to start by thanking you for the interest and sincere caring your organization has shown to the underprivileged and poor people of the island of Haiti.

After being devastated by the earthquake of January 12th of this year where countless people lost their lives and forcing countless men, women and children to live in sub-human conditions, the survivors are now faced with an outbreak of cholera that threatens all of them. With the holidays coming, we want, once again, to come up with a way to give these people a ray of hope. We want to remind them that Portlight Strategies and the good-hearted people of America have not forgotten about them; we want them to know that we share their pain and suffering.

If you watch the news as I do, you will see that the big NGOs with millions of dollars in donations are still facing the same difficulties they have since the earthquake: supplies are locked up in warehouses and not being distributed in a timely manner to help the people that need these supplies the most. After doing some research on how we can make a difference for the Holidays, I think we can accomplish the following objective:

The Sean Penn foundation had taken a special interest in a camp located in the city of Petionville that holds about 40,000 of the homeless. He started a school for primary education which provides about 250 primary school students an opportunity for a quality education. The school was being cared for by another NGO but they too stopped providing the necessary funds to sustain the school. University Quisqueya up to now has been sustaining the operation of the school which employs 8 to 10 teachers with a salary of $400.00US for each teacher. The University is also facing difficult times as the entire University’s buildings had been destroyed by the earthquake.

There is also a school on the outskirts of the city of Jacmel called Centre Educatif de Fond Jean-Noel that provides education for about 600 students from Kindergarten through High School; the students’ ages vary from 5 to 18 years old. They even have a computer lab. That school was also supported by the efforts of the University Quisqueya and again, the funding has dried up. Soon, these 800 students will be without any opportunity for organized education unless we do something. These children are in desperate need of our help.

My dream is to be able to raise enough funds to pay for the salary of about 12 to 15 teachers for the next year. $5,000.00US a month for 12 months = $60,000.00US. In addition to the salaries for the staff, they need all kinds of school supplies; backpacks, pens, pencils, notepads and even lunch boxes. My further hope is to raise enough to buy some simple Christmas presents for about 800 students to bring a small ray of hope to these children whose lives have been forever changed by this tragedy.

Also, Haiti has been without electricity for about a month now. They need good quality flashlights, batteries and lanterns to sustain them. The kids are so desperate for a decent education that they are willing to learn with a lamp.

In the face of this devastation, we can make a difference. The key to the future of Haiti will be the children we educate today; these children are the future leaders of Haiti. They can lead these people to progress, democracy and a government without corruption but only if they receive the education that we in America take for granted.

I pray that we can find God’s Grace and Blessing in this endeavor and accomplish this task. We have very little time to accomplish this task but if we give of ourselves, we can do it.

Thank you for all your support, love and caring. God bless Portlight and God Bless the United States of America.


Richard Lumarque
3013. Patrap

Is dat a spin,...?