CSU leaves their hurricane forecast unchanged; 92L and Colin's remains worth watching

By: Dr. Jeff Masters , 2:38 PM GMT on August 04, 2010

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Tropical Storm Colin was ripped apart by wind shear yesterday, and the storm's remnants are passing just north of the northernmost Lesser Antilles Islands today. Most of the heaviest thunderstorms are passing north of the islands, as seen on Guadeloupe radar. Long range radar out of Puerto Rico also shows this. Colin's remains are in a rather unfavorable environment for re-development, since the disturbance is passing beneath an upper-level low pressure system with dry air and high wind shear. Wind shear is a high 20 - 25 knots over Colin's remains this morning. Recent satellite imagery shows that heavy thunderstorm activity has increased in intensity and areal coverage over the past few hours, though, and Colin's remnants will need to be monitored for re-development.

Forecast for Colin's remains
The latest SHIPS model forecast predicts that wind shear will drop from 15 - 25 knots today to a moderate 15 - 20 knots on Thursday. Wind shear will continue to decline over the weekend, and this relaxation of shear prompts most of the major models to predict re-development of Colin sometime in the next four days. NHC is giving Colin's remain a 20% chance of developing into a tropical depression by Friday morning. A major trough of low pressure is expected to move off the U.S. East Coast on Friday, and this trough will pull Colin to the northwest and cause it to slow down. By Friday, Colin will be moving at half of its current speed. All of the major forecast models are predicting that the trough of low pressure will be strong enough to fully recurve Colin out to sea early next week. Colin's remains may pass close to Bermuda on Saturday, with the latest 06Z (2am EDT) run of the GFDL model predicting that Bermuda will experience tropical storm force winds on Saturday as Colin passes to the west of the island. The Hurricane Hunters are scheduled to investigate Colin's remains at 8pm EDT tonight. It currently appears that Colin will only be a threat to Bermuda and Canada.


Figure 1. Morning satellite image of Colin's remains and Invest 92L.

92L
A tropical wave (Invest 92) in the south-central Caribbean is moving west at 15 - 20 mph. This wave is over warm water and is experiencing low wind shear of 5 - 10 knots, and could show some development over the next two days. However, the wave's rapid westward motion should bring it ashore over Nicaragua and Honduras on Friday, or the Yucatan Peninsula on Saturday, and 92L probably does not have enough time over water to develop into a tropical depression. NHC is giving a 20% chance of this disturbance developing into a tropical depression by Friday morning. This storm was being tagged as 98L yesterday; I'm not sure why it is being called 92L today.

CSU's forecast numbers for the coming hurricane season remain unchanged
A very active Atlantic hurricane season is on tap for 2010, according to the seasonal hurricane forecast issued today, August 4, by Dr. Phil Klotzbach and Dr. Bill Gray of Colorado State University (CSU). The CSU team continues to call for 18 named storms, 10 hurricanes, 5 intense hurricanes, and an Accumulated Cyclone Energy (ACE) index 185% of average. These are the same numbers as their June 2 forecast. Between 1950 - 2000, the average season had 10 named storms, 6 hurricanes, and 2 intense hurricanes. But since 1995, the beginning of an active hurricane period in the Atlantic, we've averaged 14 named storms, 8 hurricanes, and 4 intense hurricanes per year. The new forecast continues to call for a much above-average chance of a major hurricane hitting the U.S., both along the East Coast (50% chance, 31% chance is average) and the Gulf Coast (49% chance, 30% chance is average). The risk of a major hurricane in the Caribbean is also high, at 64% (42% is average.)

The forecasters cited four main reasons for an active season:

1) Moderate La Niña conditions should be present during the most active portion of this year's hurricane season (August - October). This should lead to reduced levels of vertical wind shear compared with what was witnessed in 2009.

2) Current SST anomalies are running at near-record warm levels. These very warm waters are associated with dynamic and thermodynamic factors that are very conducive for an active Atlantic hurricane season.

3) Very low sea level pressures prevailed during June and July over the tropical Atlantic. Weaker high pressure typically results in weaker trade winds that are commonly associated with more active hurricane seasons.

4) We are in the midst of a multi-decadal era of major hurricane activity, which began in 1995. Major hurricanes cause 80 - 85 percent of normalized hurricane damage.

Analogue years
The CSU team picked four previous years when atmospheric and oceanic conditions were similar to what we are seeing this summer. Those four years were 2005, the worst hurricane season of all time; 1998, which featured 3 major hurricanes, including Category 5 Hurricane Mitch; 1952, a relatively average year that featured just 7 named storms, but 3 major hurricanes; and 1958, a severe season with 5 major hurricanes. The mean activity for these five years was 17 named storms, 11 hurricanes, and 5 intense hurricanes, almost the same as the 2010 CSU forecast.

How accurate are the August forecasts?
The August forecasts by the CSU team over the past 12 years have had a skill 21% - 44% higher than a "no-skill" climatology forecast for number of named storms, hurricanes, intense hurricanes, and the ACE index (Figure 2). This is a good amount of skill for a seasonal forecast, and these August forecasts can be useful to businesses such as the insurance industry and oil and gas industry that need to make bets on how active the coming hurricane season will be. This year's August forecast uses a new formula, so we don't have any history on how the technique has behaved in the past. An Excel spreadsheet of their forecast skill (expressed as a mathematical correlation coefficient) show values from 0.61 to 0.65 for their previous August forecasts using different techniques, which is respectable.


Figure 2. Comparison of the percent improvement over climatology for May and August seasonal hurricane forecasts for the Atlantic from NOAA, CSU and TSR from 1999-2009 (May) and 1998-2009 (August), using the Mean Squared Error. The British firm Tropical Storm Risk (TSR) will issue their outlook for the 2010 Atlantic hurricane season on June 4. Image credit: Verification of 12 years of NOAA seasonal hurricane forecasts, National Hurricane Center.

The British private forecasting firm Tropical Storm Risk, Inc. (TSR) is scheduled to release their August forecast later today. NOAA will also be issuing their August forecast sometime in the next week.

This season has had three named storms so far (Alex, Bonnie, and Colin.) It will be difficult to have a season with 19 or more named storms, since the four seasons that had at least 19 named storms all had at least five named storms by this point (August 4.) These four seasons were 1887, 1933, 1995, and 2005.

Next update
I'll have an update on Thursday morning.

Jeff Masters

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Im guessing ex Colins coc would be around 22N, 63W ish?
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611. 7544
hmmm no more dry air for colin
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Haboob...makes alot of sense...thx
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i do not see Colin comeing back too life then yet you nevere no
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607. BA
JB called Colin surfer storm on his video today :)
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Quoting StormChaser81:


Oh well I tried


LOL!
Member Since: August 28, 2006 Posts: 6 Comments: 2895
On the animated visible floater image of ex-Colin there is a spin just above Porto Rico that is starting to draw-in clouds, is this an ULL?
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We have thunderstorms up and down the Gulf Coast. Why is that important? See we should have had thunderstorms everyday with the heat we have had and dew points over 80F. Even this morning we at a dew point depression of 4F and TS were having a rough go at forming up. This means the capping high is breaking down or shifting out. This will affect the steering currents. If the ridge weakens or the high moves then 92L might have a better shot shifting to a more northerly track. Depends how much it breaks down on how much of a shot it has to get into the Gulf. Not saying it is going to hit the Gulf coast just saying it can shift to the north a bit. Something to watch.
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603. BA
Quoting OneDrop:

Has that look but the angle of the picture looks more like Pipe since Teahupoo angles are usually from the water at a safe distance


ooops, I just looked at my image on my profile here here and it is totally different than the one I was thinking, that isn't even close to teahupoo heh
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Quoting Abacosurf:


Contest at Teahpoo later this month.



tomorrow offshore winds and 5-7ft forecast for north shore PR
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600. Skyepony (Mod)
Dismal model performance on Colin..CMC still leads followed by gfs ensemble, HWRF...


Average Position Error (nm) for core models
model Error Trend 24hr Error 48hr Error 72hr Error Day 4 Error Day 5 Error
CMC INCREASING 71 208.9 248.6 -1 -1
AEMN DECREASING 83.1 121.2 -1 -1 -1
HWRF DECREASING 93.6 226.3 364.1 -1 -1
GFDL DECREASING 114.9 204.5 313.1 -1 -1
OFCL INCREASING 126.7 170.5 -1 -1 -1
MM5B INCREASING 128.1 273.1 438.4 -1 -1
LBAR INCREASING 156.1 286.3 371.7 -1 -1
BAMD INCREASING 183 364.4 584.5 -1 -1
MM5E INCREASING 231.7 415.7 -1 -1 -1
KHRM DECREASING 308.2 686.5 -1 -1 -1
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599. BA
Quoting Abacosurf:


Contest at Teahpoo later this month.



I will be working :(
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is it me or does Colin look better now than yesterday?
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Quoting OneDrop:

He is a little bit entertaining at times and annoying at other times. I'll tell you this, the Thursday before Wilma hit South Florida, he told us to get prepared for a big storm to hit on Sunday and I did that Thursday night and that was huge!! I was so prepared that I ate better the 7 days after the storm than I did the 7 days before and I had loads of gas and while people were in line waiting for gas I was on my way fishing since the boat was gased up, I had plenty of ice and the fishing turned out to be on fire!!! Funniest part to the story is that on Sunday night while everyone was in line buying last minute supplies, my wife and I were buying just a chocolate cream pie to take to a friends house for a BBQ turned hurricane party we had planned the week before and people looked at us like we were nuts!!


The Thursday before, huh? Boy, he really went out on a limb, didn't he? Imagine that: JB was the only one to call for Wilma to landfall in South Florida...



...or not. ;-)
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Quoting PensacolaDoug:



They can't forecast half as good so they tear him down to make they're pitiful selves feel better. It's ok we understand.


Yeah, I'm making my "pitiful" self feel better. The only reason you have a man-crush on JB is because of his politics which makes you the pitiful one. Get real.
Member Since: August 28, 2006 Posts: 6 Comments: 2895
595. BA
Quoting StormChaser81:


Oh well I tried


they are good links for everyone anyway...so time well spent :)
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Just looking at some of the models, the GFS and CMC take Colin like right next to nova scotia.... Wonder if we gonna get a flyby like Bill did last year :P
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Quoting 2010StormNames:
No problem, Taz, :). Glad to be of help.



so where dos the gfs track all the storms?
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591. BA
Quoting OneDrop:

He is a little bit entertaining at times and annoying at other times. I'll tell you this, the Thursday before Wilma hit South Florida, he told us to get prepared for a big storm to hit on Sunday and I did that Thursday night and that was huge!! I was so prepared that I ate better the 7 days after the storm than I did the 7 days before and I had loads of gas and while people were in line waiting for gas I was on my way fishing since the boat was gased up, I had plenty of ice and the fishing turned out to be on fire!!! Funniest part to the story is that on Sunday night while everyone was in line buying last minute supplies, my wife and I were buying just a chocolate cream pie to take to a friends house for a BBQ turned hurricane party we had planned the week before and people looked at us like we were nuts!!


yeah, I don't necessarily like him because he is right all the time or something, he is wrong times just like everyone else, however, you can learn a lot watching his videos...I happen to like his humor :) ...I can do without some of his ranting on "you know who" though

that being said, apparently he is right enough for private clients to pay him big bucks...over the past few years, I think he actually reserves a lot of his comments for his private clients...and we only get a certain bit of it as pro customers
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590. unf97
Quoting 7544:
could wave at 47west become 93l and whats that huge blob behind it


This wave would have to gain some latitude and separate from the ITCZ to have any chance of development. Also, it is moving due west, and it appears that it will interact with South America very shortly. To sum it up, development not expected with this area.
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588. 7544
colin trying to shape up again ngp pputs him off the est coast of fla
and takes another wave to the bahamas check it we may see 93l real soon

Link
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It looks like ex-Tropical Storm Colin is going to graze Bermuda on Saturday.

Colin looks more like a tropical storm now. They did find some tropical storm force winds but no closed circulation.
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Quoting HaboobsRsweet:
On a serious note does anyone notice a weather event occuring on the Gulf Coast as we speak that could totally shift tracks and forecasts?
I posted the GEM model this morning. It shows the low forming on the northern gulf coast.
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Quoting BA:


been there, done that, none have near the options accuweather pro does on the ECMWF, thanks though


Oh well I tried
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Quoting 2010StormNames:


For now, yes it is, Taz! However, it's showing a lot of potential storms forming out in the EATL, in it's long ranger.



ok
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580. BA
Quoting StormChaser81:


ECMWF

ECMWF

ECMWF

ECMWF

ECMWF


been there, done that, none have near the options accuweather pro does on the ECMWF, thanks though
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On a serious note does anyone notice a weather event occuring on the Gulf Coast as we speak that could totally shift tracks and forecasts?
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Quoting NewYork4Life:


384hrs from now the earth could have been hit by an asteroid rendering this post completely pointless...
Yours or his?
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Quoting BA:
would have to double check what image I used, thought I used teahupoo


Contest at Teahpoo later this month.

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Quoting wayfaringstranger:
What was TSR's predictions for this year?



TSR is forecasting a very busy hurricane season. 16 storms, 9 hurricanes, 4 major hurricanes.
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Quoting Jeff9641:


what's up bud! I wish we could share some of that rain you guys on the W Coast of FL been getting here in E C FL.


localized street flooding yesterday from that storm that came through around 330pm

it rained again around 7pm too and continued to thunder until about 10
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Quoting Hurricanes101:


my problem is no one was being overzealous, it was just posted and there was no need to comment and make people feel stupid for commenting

we all know its 16 days out, we are fully aware things can change and none of us are relying on anything.

So I ask again, why the comment? Just so you can be heard?

It is all good man...no not to be heard or I would post a lot more. I tend to not post much anymore because I get called a downcaster yet the only one I truely blew was Bill last year. I am ok with that though. I am sure I will screw up another one. If peole want to read what I have to say cool...if not I am ok with that too.
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I was thinking about that yesterday.

Yesterday, the models was flirting with a carribean wave developing into a possible named storm in the GOM.
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Quoting BA:
would have to double check what image I used, thought I used teahupoo

Has that look but the angle of the picture looks more like Pipe since Teahupoo angles are usually from the water at a safe distance
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Good tempo on the blog today. SWFL is about to get blasted, especially naples
Member Since: July 30, 2005 Posts: 1 Comments: 960
Quoting Hurricanes101:


very well said and it isnt like the long range hasnt been right before

Dean and Felix anyone?



can some one plz tell me what the gfs been up too today have they been playing nic with us
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566. BA
would have to double check what image I used, thought I used teahupoo
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Quoting DestinJeff:
I notice something with long-range models, such as the case with the 384 GFS. It shouldn't be so problematic that someone mentions the 384 solution ... it still can serve as a baseline for conistency.

For instance, if the 384 solution continues to be the same in subsequent runs (decreased hour), then that shows model consistecy. You always see "too far out, not worth looking at" but I just don't understand why that expression is so popular. I mean, they run the model to that point for a reason.


very well said and it isnt like the long range hasnt been right before

Dean and Felix anyone?
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What was TSR's predictions for this year?

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Quoting HaboobsRsweet:

That so called low will be a high on the model next week haha. I can just see people get over zealous because a model is showing something like that. That is all. Just my opinion just like it was there. My opinion is that it is useless looking at it that far out. Nothing wrong with him posting that out there.


my problem is no one was being overzealous, it was just posted and there was no need to comment and make people feel stupid for commenting

we all know its 16 days out, we are fully aware things can change and none of us are relying on anything.

So I ask again, why the comment? Just so you can be heard?
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I didnt say anyone was wishcasting...I dont use that word. I say over forecasting haha.

With that said I think there is a huge clue on the Gulf Coast today of what can happen with 92L or the weak low someone pointed out forming off the coast in a few days.. Anyone know what that is?
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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.