More pre-season predictions of a very active Atlantic hurricane season
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
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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.
If that ends up being the case, then I'll consider it a candidate for retirement. My own criteria, however, is very strict.
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
Looks like a perfect little eye..
not to get excited about I don't think but cool none the less
Arlene.
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.
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.
Yeppers...the first named storm for next year.
Going to bed, just had to look up the name Arlene before I did. LOL
You said it!
Don't you be stealing any of my globes while I am off. I have been watching all day.
The Mexican Government has MANY serious problems. They even charge their own citizens for relief supplies, very, very, very disturbing.
I reviewed the pictures out of Monterrey, Mexico. The damage was catastrophic, the damage to roads, bridges, infrastructure throughout the entire Monterrey Greater Metro Area.
Remote villages were cut off, only the Master of all dimensions knows how many smaller mountain villages were wiped off the face of the Earth, how many lives were lost and how many people who weren't accounted for.
They received 18-36" of rain in 48 hours. The annual rainfall in that area is 18" a year. A fellow WU blogger reported on our blog the shear shock and amazement of how much damage was done in Monterrey proper. People in that city of 1.5 million people were BEGGING for help. Sadly, their cries went unanswered for many days, until the Mexican Government rushed in aid.
Thanks StormW :) -so main distinctive factors are max winds farther from eye and no fronts associated. Good to know!
but your gonna miss the COC argument that is about to ensue!
Grothar's the best when it comes to tracking cyclones, he's been tracking them for years.. all the way back to the Lincoln administration. Ha kidding.
Not on my end.
WHO normally does not retire storms that primarily affect Haiti. Due to the fact that most of the damage that is done to Haiti could be prevented. As an example deforestation has probably contributed to storms that have killed many people in Haiti from landslides as well as fast moving flood waters such as Gordon from 1994 and Hanna in 2008.
1096. Tazmanian 1:43 AM GMT on July 13, 2010
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
Not a stretch...his baby pictures were taken by Mathew Brady.
Nah, but he's been trackin em well longer than StormTop claims he has.
Quoting Tazmanian:
you guys skip right ovee commet 1096
We were trying not to notice you can't even spell NOSE. ;)
POOF
would any one like too joine him???
i will not have none of that
I consider it a badge of honor!
And while I agree BP should pay, I also keep recalling the involvement of Halliburton in both this and the Australian blowout, which took place at a suspiciously similar point in the drilling process.
2005 was a very bad season for Mexico and the US. At least we seem to have benefited in terms of improved forecasting for the entire basin. Let's hope the world gets more from DWH disaster than an opportunity to bash oil executives, US politians, and TV personalities....
He wasn't as tall as one might think. His hat enhanced his appearance. Anything in the tropics of interest. I have been too busy to drop in today. Unlike some here, I have a life. LOL Boring, but it's all mine.
Taz, I'm glad you referenced it again b/c I did miss it. It's making me laugh -- probably mostly b/c I don't get it but welcome a good sense of humor. ;)
Would this be winds at mid level?
your welcome
LMAO Honor... I would like to thank the academy for this Badge of honor!! Woohooo... Back to what matters... Oil and Hurricanes
yup
Out of deep respect for Taz, who adds many important things to our blog, folks, do not insult him PERIOD. He is very bright and adds things to this blog that even the professional meteorologist sometime miss.
This is a Tropical Weather Blog, not a Spelling Blog, not a Spelling Bee. Anyone who wants to bicker, please go hang out on another blog or internet media. Thanks!
I am still hearing you and others say that the Coast Guard passes the buck. That is disgraceful to the men and women of that service.
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