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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1964. sky1989
Quoting TexasHurricane:


What did he/she do? I only started coming on here last year. Seems like the majority on here don't want him/her here....just curious.


I have been here for 3 years, mostly lurking though, and have still not figured that out! lol.
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1963. JLPR2
Just let the guy be -.-

Of course, if he starts insulting people then I support the reporting him, but if not, eh... what the heck!
I'm tired of this happening everyday. *sigh*

Also, looks quiet in the Atlantic, I just hope it stays that way for a loooooong time, sorry I know some will loose their sanity, but I'll take quiet conditions any day. =)
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Quoting TexasHurricane:


What did he/she do? I only started coming on here last year. Seems like the majority on here don't want him/her here....just curious.

I've been wondering the same thing!
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Quoting MiamiHurricanes09:
WARNING! JFV has returned yet again with the handle "jfv24". Once he signs on to this blog please report and ignore him immediately.


What did he/she do? I only started coming on here last year. Seems like the majority on here don't want him/her here....just curious.
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1956. 47n91w
Quoting BahaHurican:
That is a really poetic way of capturing their fragrance ...


Hard to put the experience into words. I visited a Fragipani at dusk. In the darkness the white flowers glowed while the thick scent enveloped the entire tree. It's one of those moments where you wish life had a pause-button.
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Quoting StormW:
That's not dust



This is dust


LOL
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RE: 2010 season predictions.
I went back an looked at some historical season data, and also at cool phase PDO years which also occurred near Solar Minimums in the past, as far back as I could go. Since the PDO last changed phase (from cool to warm) in 1978 or so, most of the applicable storm season records predate the satellite era. What I saw though was, on average, only about 5-6 landfalling storms during these years, with most recuving through the Gulf of Mexico into the southern states, and only a couple threatening the east coast.

From this casual observation I draw two rough conclusions. First, the storms remain weaker, or fail to develop into tropical storms/hurricanes due to climatic and/or solar influences until reaching the seasonably warm waters of the Caribbean or Gulf of Mexico. There were still land-falling major hurricanes so this does not mean they remain weaker once reaching the Gulf. Second, being weaker in the Atlantic and Caribbean, they have a harder time fighting the Bermuda High, or due to climatic influences, the BH sets up farther to the west, closer to the Eastern US seaboard.

I did not, in any year with a cool PDO and Solar Minimum, find any season as active as what this year has been predicted to be. I'm arguing that a combination of developing La Nina, cool Pacific Decadal Oscillation phase, and the Solar Minimum will all combine to prevent the "season o' doom" which was predicted.

Anyone else with thoughts about this. I cross referenced Wikipedia storm season data with Solar Min/Max charts, and finally looked at the roughly 30 year PDO cycle to get in the ballpark. It ain't exactly a scientific method but it's what I had available.

I'd say my "guesstimate" is somewhere less than 12 named storms, total, with 5-8 landfalling as hurricanes. At least three hurricanes making landfall will be major and will strike the US.
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Quoting BahaHurican:
I think from climatological study, trackwise a Neutral/laNina bias is the most likely setup for US landfalls, especially if one is thinking multiple landfalls per season. But even this is not autamatically true every time this situation occurs. There a numerous other variables to consider, some of which we can only predict 1-2 weeks out with any accuracy, and others which we don't fully understand.


Precisely!
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The only real limiting factors on the upcoming season, other than the normal increase in sheer towards the end of the season, would usually be SAL and dry air issues choking off incipient CV storms in spite of favorable sheer and SST's as they cross the Atlantic into the Antilles. Short of some persistent SAL outbreaks as noted durng the heart of the season, or, an early increase in sheer lets say around October for an early shut-down, no reason, yet, to suspect that the current numbers from NHC and Gray, etc. will not come to pass this year.
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OMG look oh this posted on my blog
Member Since: May 21, 2006 Posts: 5091 Comments: 115255
Quoting BahaHurican:
Aww... and I was trying to share the beauty... guess I shouldn't post the mango ones, then... lol


Thanks, by the way...they are very beautiful
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Quoting 47n91w:


I had the privilege of standing beneath a white-flowering Fragipani once. Those could have been my last breaths, and I wouldn't have cared.
That is a really poetic way of capturing their fragrance ...
Member Since: October 25, 2005 Posts: 19 Comments: 22357
1943. KEEPEROFTHEGATE (Mod)
Quoting Drakoen:


We still have August, September, October, and November


numbers remain the same
if after aug 15 its still the same
then numbers will be adjusted
according to conditions

ATLANTIC SEASON NUMBER OUTLOOK

TOTAL STORMS 21 TO 23
TOTAL HURRICANES 11 TO 14
TOTAL MAJORS 5 TO 7
TOTAL CAT 5's 1 TO 3
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I was saying the same thing this morning that wave is clearing a path for that wave that is about to come off of the coast of Africa

link to loop Link
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1940. angiest
Quoting BahaHurican:
This is a frangipani bract from my back yard:



.... a closeup...



... and a view showing the leaf crown around the flowers...



Frangipani come in this vivid pink and also in a waxy / creamy white, and the scent in remarkably sweet and powerful...


Meanwhile, in Houston, a rarity: A cultivated Corpse Flower (Amorphophallus titanum) will soon be blooming. Apparently this has only happened about 30 times in the US. The flower smells of rotting flesh, hence the common name. The reason for the scientific name is left as an exercise to the reader.

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Quoting KarenRei:
SAL getting weaker and shifting north.

Yesterday (had already weakened but not shifted much north yet):


Today:




There's a wave free area in wesat Africa, but the wave train appers to be fairly healthy in central and east Africa:

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1938. 47n91w
Quoting BahaHurican:
This is a frangipani bract from my back yard:



.... a closeup...



... and a view showing the leaf crown around the flowers...



Frangipani come in this vivid pink and also in a waxy / creamy white, and the scent in remarkably sweet and powerful...


I had the privilege of standing beneath a white-flowering Fragipani once. Those could have been my last breaths, and I wouldn't have cared.
Member Since: Posts: Comments:
Quoting Floodman:


Baha, it's a mean person that rubs it in like that!
Aww... and I was trying to share the beauty... guess I shouldn't post the mango ones, then... lol
Member Since: October 25, 2005 Posts: 19 Comments: 22357
Quoting MiamiHurricanes09:
Just because conditions are unfavorable for development now, that doesn't mean they're going to be that same way throughout the entire season. With all the factors in place for a hyperactive season, I don't see why numbers/forecasts should be lowered.

I believe most people are considering to lower their numbers because the Atlantic is inactive at the moment, if there were a hurricane out there you wouldn't be lowering your predictions.

Amen!
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The 2010 season is just starting as the climbing of the mountain has not begun yet.

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Quoting Drakoen:


We still have August, September, October, and November


yeah....the ones we get seem to be in September...Rita,Humberto and Ike.
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Quoting Floodman:


Historically La Nina conditions result in more CONUS landfalls and someone correct if I'm wrong, but the stronger the La Nina event, the further south the tracks tend to go; the AB hgh is supposed to be a little weaker but a little further west in extent as we move forward

Asking about a specific area for landfall is kind of useless; no one can predict with any certainty the liklihood of one area over another getting hit...the only tjhing we have there is climatology and historical track
I think from climatological study, trackwise a Neutral/laNina bias is the most likely setup for US landfalls, especially if one is thinking multiple landfalls per season. But even this is not autamatically true every time this situation occurs. There a numerous other variables to consider, some of which we can only predict 1-2 weeks out with any accuracy, and others which we don't fully understand.
Member Since: October 25, 2005 Posts: 19 Comments: 22357
Just because conditions are unfavorable for development now, that doesn't mean they're going to be that same way throughout the entire season. With all the factors in place for a hyperactive season, I don't see why numbers/forecasts should be lowered.

I believe most people are considering to lower their numbers because the Atlantic is inactive at the moment, if there were a hurricane out there you wouldn't be lowering your predictions.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
1930. Drakoen
Quoting Stormchaser2007:
Its going to take a heck of a lot of cramming to get 20 storms.

Im going down to 17.



We still have August, September, October, and November
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1929. sky1989


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SAL getting weaker and shifting north.

Yesterday (had already weakened but not shifted much north yet):


Today:


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Quoting BahaHurican:
This is a frangipani bract from my back yard:



.... a closeup...



... and a view showing the leaf crown around the flowers...



Frangipani come in this vivid pink and also in a waxy / creamy white, and the scent in remarkably sweet and powerful...


Baha, it's a mean person that rubs it in like that!
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Its going to take a heck of a lot of cramming to get 20 storms.

Im going down to 17.

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1923. sky1989


Relentless
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Quoting kshipre1:
To user name Bordonaro,

Thank you for your response to my question earlier. Just curious what does Dr. Masters think about the chances of hurricane landfall in South and Western Florida this year?

Since La Nina is almost here what does this mean for hurricanes in Florida and what is the projected location of the Bermuda High? Thanks


Historically La Nina conditions result in more CONUS landfalls and someone correct if I'm wrong, but the stronger the La Nina event, the further south the tracks tend to go; the AB hgh is supposed to be a little weaker but a little further west in extent as we move forward

Asking about a specific area for landfall is kind of useless; no one can predict with any certainty the liklihood of one area over another getting hit...the only tjhing we have there is climatology and historical track
Member Since: Posts: Comments:
1919. Drakoen
It is still very possible that we could see 18+ named storms in the Atlantic Basin.
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This is a frangipani bract from my back yard:



.... a closeup...



... and a view showing the leaf crown around the flowers...



Frangipani come in this vivid pink and also in a waxy / creamy white, and the scent in remarkably sweet and powerful...
Member Since: October 25, 2005 Posts: 19 Comments: 22357
Quoting Jedkins01:




I don't think I could stand calculus in the summer! lol


That's the best time to take those engineering mathematics courses. The classes are smaller and shorter. The they are somewhat faster paced. At least that is how I found them to be for myself. That allowed more time for the METR courses in the spring and the fall semesters.
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Quoting StormW:


Total Named Storms: 17-19
Hurricanes: 9-11
Intense Hurricanes: 4-5


That is still a decent amount of storms...do you look for these to go above the carribean and go more toward the Florida to Mississippi area (or the east coast)or go under the carribean to the gulf going to Mexico to Louisianna area?
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Quoting sky1989:


2002 and 2004 both had 8 named storms in August. And 2007 had 8 named storms in September. I just have a feeling this year that we may not get the extremely high numbers but we may have some very strong and long-lived storms like 2003 and 2004.


That may very well be true; I was certainly expecting more from the early Carib season; guess it will all depend on the CV waves and the late Carib season

There was some discussion here in the last week or so about the fact that the expanse of warm SSTs maybe too extensive, causing a lack of focus for the heat energy, but to be honest, how many well organized waves have developed since the the season started? There hasn't been anything to really take advantage of the warm SSTs...
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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.

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