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 btwntx08:

tell the cmc that lol

How many other computer models are in agreement with the CMC as of the last model run?
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Quoting StormW:


If I've done my research correctly, yes. As it moves east, given the outer side of 2 is near the Indian Ocean, it would seem Africa has to be within Octant 2. We usually see development once the MJO crosses into 2


thank you Sir!
Member Since: July 1, 2005 Posts: 10 Comments: 1683
Quoting Patrap:


all the info is here on the Deep Water Horizon official Site.

www.deepwaterhorizonresponse.com

My concern is what is going to happen when the pressurize that containment dome.

I question whether or not that vessel will actually withstand those pressures. I hope all goes well, we already have a big enough problem.
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1607. Patrap
Quoting DestinJohn:
Dr Masters.... Can you please provide an Oil Spill Update with your next blog??? Lots of folks on the Gulf rely on your collection of information and trust your predictions....


all the info is here on the Deep Water Horizon official Site.

www.deepwaterhorizonresponse.com

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*****Repost**** from 1600
Morning Storm




So on this chart would you say that section 1 and 8 represent the whole tropical atlantic and africa? 8 being the the Caribbean Sea and the Gulf?

am I understanding that correctly?
Member Since: July 1, 2005 Posts: 10 Comments: 1683
Dr Masters.... Can you please provide an Oil Spill Update with your next blog??? Lots of folks on the Gulf rely on your collection of information and trust your predictions....
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Quoting stillwaiting:
whats up HJ???,looks like someones gonna throw "gasoline in the fire" as we head into the end of the month,I wouldn't discount us watching 2 or more TC's develop in the basin thru then!!!


Yeah, seems that way, huh? Conditions look ripe for a little uptick! Haven't seen you on my site in a while. Glad you're still kickin!
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1601. Patrap
NASA: First half of 2010 breaks the thermometer — despite “recent minimum of solar irradiance”
July 10, 2010




Blue curve: 12-month running-mean global temperature. Note correlation with Nino index (red = El Nino, blue = La Nina). Large volcanoes (green) have a cooling effect for ~2 years. Source: “Global Surface Temperature Change,” by James Hansen et al., June 2010.

Following fast on the heels of the hottest Jan-May — and spring — in the temperature record, it’s also the hottest Jan-June on record in the NASA dataset [click on figure to enlarge].

It’s all the more powerful evidence of human-caused warming “because it occurs when the recent minimum of solar irradiance is having its maximum cooling effect,” as a recent must-read NASA paper notes.

[For daily updates on climate science, politics, and solutions, click here.]

Software engineer (and former machinist mate in the US Navy) Timothy Chase put together a spreadsheet using the data from NASA’s Goddard Institute for Space Studies (click here). In NASA’s dataset, the 12-month running average temperature record was actually just barely set in March — and then easily set in April and topped out in May.

It still seems likely that 2010 will be the hottest year on record, but NOAA now predicts that “La Niña conditions are likely to develop during July – August 2010.” If the La Niña comes fast and deep (as in 1998 and 2007), that could make it a close call in the NASA dataset — and even more so in the satellite record, which is much more sensitive to ENSO ( El Niño Southern oscillation).
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Morining Storm. I just read your update







So on this chart would you say that section 1 and 8 represent the whole tropical atlantic and africa? 8 being the the Caribbean Sea and the Gulf?

am I understanding that correctly?
Member Since: July 1, 2005 Posts: 10 Comments: 1683
Quoting stillwaiting:
whats up HJ???,looks like someones gonna throw "gasoline in the fire" as we head into the end of the month,I wouldn't discount us watching 2 or more TC's develop in the basin thru then!!!

Yes, by the end of the month it appears that someone will pour 105 octane high-test gasoline on the CV region!
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00z 192 hours out ECMWF. Look at how huge that wave between the Caribbean and Africa is!

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Quoting Drakoen:
ECMWF




Did someone say massive CV development?
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whats up HJ???,looks like someones gonna throw "gasoline in the fire" as we head into the end of the month,I wouldn't discount us watching 2 or more TC's develop in the basin thru then!!!
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Quoting angiest:


That was a joke....

I know :o)! Hopefully nothing too big affects the S TX Brownsville, TX area.
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Quoting ackee:
Seems like shear and dust will put a damp on the hyper active seasons most agent was forecasting oh where is La nina ? some forecast La nina forming by july and reduceing vertical wind shear that has not happen either with that see no more than 15 name storms


La Nina is on the way......Just give it a few weeks just in time for August and September:

Issued on Wednesday 7 July 2010 | Product Code

Sea surface temperatures in the central equatorial Pacific have continued to cool over the past fortnight, and hence the tropical Pacific is now generally cooler than average east of the date-line. Below the surface, temperatures also remain significantly cooler than average, with some areas more than 4°C cooler than normal. Trade winds in the western Pacific remain stronger than normal and cloudiness near the date-line continues to be suppressed. These indicators, together with the Southern Oscillation Index (SOI), which has been positive since April, are consistent with the developing stages of a La Niña event.

The majority of climate models surveyed by the Bureau suggest current patterns and trends will continue, with a significant likelihood of further ocean cooling beyond La Niña thresholds before the end of the southern winter.

Member Since: August 8, 2006 Posts: 0 Comments: 8715
1590. angiest
Quoting Bordonaro:

Of course not. The current trend, per the computer models, is a wave developing in the W Caribbean region, slowly heading towards S TX.

No one hates Brownsville, TX. Every region in the Tropical Atlantic goes through "phases or cycles" of increased development and for the moment, much of the action is in this W Caribbean into the SW GOM.


That was a joke....
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Quoting angiest:


Does someone hate Brownsville this year?

Of course not. The current trend, per the computer models, is a wave developing in the W Caribbean region, slowly heading towards S TX.

No one hates Brownsville, TX. Every region in the Tropical Atlantic goes through "phases or cycles" of increased development and for the moment, much of the action is in this W Caribbean into the SW GOM.

For example, although I wasn't around then, back in 1954-1955 a series of pretty nasty Hurricanes shot up the Eastern Seaboard and wreaked havoc, from NC to Canada.

There was Edna, Carol, Hazel who created major problems for the E Coast.
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Quoting stillwaiting:
wave getting ready to exit africa should be our first CV TC IMO!!!!


Morning dude! How's it going?
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Quoting StormW:


Should happen in about 10 days.

Thanks, as we go into a -NAO, with a 700MB moistening and the MJO upward pulse and the inverted V trough coming off Africa, looks like everyone needs to get ready for our first CV waves to take shape..

As the Tropics start to yell, "Gentlemen, start your engines"!!
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1584. angiest
Quoting btwntx08:


Does someone hate Brownsville this year?
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Thank you

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so what does all that mean storm the graph of the MJO
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Quoting weatherguy03:
Tropical Update w/ Video

Very nicely put together, thanks!
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I hate to say it...... but Im ready for some excitement on the weather front!!!!
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1578. Drakoen
Quoting SunnyDaysFla:
Re#1572

I know to watch whether it is in quadrant 1 or 2---but what are all the yellow lines?


The ensemble members...51 of them
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Re#1572

I know to watch whether it is in quadrant 1 or 2---but what are all the yellow lines?
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Tropical Update w/ Video
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1572. Drakoen
ECMWF

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Quoting StormW:
TROPICAL WEATHER SYNOPSIS JULY 13, 2010 ISSUED 10:00 A.M.

StormW, when do you believe the SAL layer will begin to subside?
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wave getting ready to exit africa should be our first CV TC IMO!!!!
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lets go yankees!!!,lets go yankees!!!,lets go yankees!!!,gotta love em.......probably the most important team in the league IMO...
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1568. IKE
Quoting WSVN:
For now, Ike?


Yeah...for now.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
R.I.P. "Big George",we love ya and will miss ya.....Goooooo Yankees!!!!!!
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1565. IKE
Quoting portcharlotte:
Bastardi's blog

In the end, there is only one debate left about the entire warm season this year, and that is the hurricane season, which has shut down since the first revving-up. Cloud shots indicate a large-scale wave in the east-central Atlantic, and this will be something to watch as it will be in the Bahamas this weekend, but right now dry air is killing its convection. There was an SOI downturn in June, but it's cranking again now as the La Nina base state is really starting to go. A cooling Pacific, still warm Atlantic and positive height anomoly over the Great Lakes in the means for the hurricane season, along with a very warm AMO (latest is .495, second only to 1998 for June.. a year similar to this that really revved up in the heart of the season) all means that its no time for the faint of heart for the Atlantic season. We do have a Pacific typhoon and the western North Pacific has increased to 8% of normal, while the Atlantic and southeast Pacific together are actually above normal so far with the ace index. Overall global activity remains below normal, a little over 85%.




1998 had one named storm through Aug. 18th....then had 13 more.

And I agree with Bastardi...the Atlantic has shut down.
Member Since: June 9, 2005 Posts: 23 Comments: 37858

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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.