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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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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Quoting Hurricanes101:


It almost never is, I am starting to realize that the word wishcaster is way overused on this blog and a majority of the time it is not even warranted
Agreed.
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Quoting MiamiHurricanes09:
Just goes to show how favorable conditions are going to be. It wasn't meant for people to rely on it.



09 i been gone and i come back on find that the GFS have been cooking up a lot of name storms where are they all going?
Member Since: May 21, 2006 Posts: 5089 Comments: 114060
Quoting Hurricanes101:


omg we are so sorry for even bringing it up lol

you are kidding right? Just because someone notices and posts it here, does not mean that anyone is relying on anything

give it a rest

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.
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Quoting MiamiHurricanes09:
Just goes to show how favorable conditions are going to be. It wasn't meant for people to rely on it.


It almost never is, I am starting to realize that the word wishcaster is way overused on this blog and a majority of the time it is not even warranted
Member Since: March 10, 2010 Posts: 1 Comments: 7233
Quoting BA:


send me a private message with free links to the ECMWF data they have...that is what I'm most interested in and I haven't been able to find it anywhere else, I generally only subscribe during the official hurricane season since I live on the coast and I like to look at as much info as I can, I've liked JB since back in his "free" days

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!!
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Quoting JLPR2:


But I'm in the mood for Chili's. XD



Hello! Didn't you start school today, already out?

Yeah, the school lets out early (12:30 pm) due to some maintenance issues. So not many classrooms are usable.
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Quoting HaboobsRsweet:
384 hours out? Wow I thought some people here relied on models too much when just looking at 144 hours but gezz man 384 hours out? Not even worth looking at that far out.
Just goes to show how favorable conditions are going to be. It wasn't meant for people to rely on it.
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552. JLPR2
Well I'm out for a little while, my last final, yeah!!
XD
Later!
Member Since: September 4, 2007 Posts: 7 Comments: 8459
all so it looks like 92L is moveing WNW at this time
Member Since: May 21, 2006 Posts: 5089 Comments: 114060
Quoting BA:


send me a private message with free links to the ECMWF data they have...that is what I'm most interested in and I haven't been able to find it anywhere else, I generally only subscribe during the official hurricane season since I live on the coast and I like to look at as much info as I can, I've liked JB since back in his "free" days


ECMWF

ECMWF

ECMWF

ECMWF

ECMWF
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Quoting unf97:


I think it is well on its way to becoming our next invest Tazmanian.



cool
Member Since: May 21, 2006 Posts: 5089 Comments: 114060
Quoting HaboobsRsweet:
384 hours out? Wow I thought some people here relied on models too much when just looking at 144 hours but gezz man 384 hours out? Not even worth looking at that far out.


omg we are so sorry for even bringing it up lol

you are kidding right? Just because someone notices and posts it here, does not mean that anyone is relying on anything

give it a rest
Member Since: March 10, 2010 Posts: 1 Comments: 7233
Hurricanes101 looks like the mode runs are showing a lot of name storms
Member Since: May 21, 2006 Posts: 5089 Comments: 114060
546. unf97
Quoting Tazmanian:
could this be come 93L?




I think it is well on its way to becoming our next invest Tazmanian.
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545. 7544
could wave at 47west become 93l and whats that huge blob behind it
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384 hours out? Wow I thought some people here relied on models too much when just looking at 144 hours but gezz man 384 hours out? Not even worth looking at that far out.
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Wikipedia. Joe Bastardi.
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We're about to get hit by a pretty strong thunder storm here in Panama City. It looks like two cells ran into each other right over us. The sky looks crazy right now.
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Quoting Hurricanes101:
536. NewYork4Life 7:01 PM GMT on August 04, 2010

Im sorry but I was not aware it was against the law to look at a long range forecast model and note that it develops 4 storms

Especially considering it is the new GFS; which has tended to be very conservative since it first was introduced

On behalf of all of us here, we apologize for saying anything


I'm just messin with ya buddy! :)
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Quoting Jeff9641:



Joe Bastard from Accuweather.com.


Bastardi
Member Since: August 26, 2006 Posts: 16 Comments: 4766
536. NewYork4Life 7:01 PM GMT on August 04, 2010

Im sorry but I was not aware it was against the law to look at a long range forecast model and note that it develops 4 storms

Especially considering it is the new GFS; which has tended to be very conservative since it first was introduced

On behalf of all of us here, we apologize for saying anything
Member Since: March 10, 2010 Posts: 1 Comments: 7233
Quoting Jeff9641:



Joe Bastard from Accuweather.com.


lmao - surely thats not his last name??
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532. MScasinojunkie 7:00 PM GMT on August 04, 2010
Quoting Jeff9641:
This JB guy is a freak!


who are you

Joe Bastardi
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Quoting Tazmanian:




wow


We should begin large scale evacuations of the entire East Coast...
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534. xcool
Tazmanian i thinks so.
Member Since: September 26, 2009 Posts: 2 Comments: 15603
Quoting PensacolaDoug:



Do you have an accuweather pro account? If not, how would you know what they offer?


I have a friend with it and watch him use it all the time.
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Quoting Jeff9641:
This JB guy is a freak!


who are you guys talking about??
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could this be come 93L?


Member Since: May 21, 2006 Posts: 5089 Comments: 114060
Quoting OminousCloud:
so florida is 100% in the clear??


Florida is in the clear until we have a negative NAO and the A/B high moves potential storms more to the west.
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529. xcool
HA
Member Since: September 26, 2009 Posts: 2 Comments: 15603
Quoting MiamiHurricanes09:
Here is what Drakoen was referencing to:

Here it is at 324 hours emerging off of Africa, as you can tell it already is a potent tropical storm.



By 384 hours it is a strong hurricane with 6 closed isobars and many hurricane force wind isobars. Also notice the tropical cyclone making landfall over the Yucatan.





wow
Member Since: May 21, 2006 Posts: 5089 Comments: 114060
526. hercj
Quoting StormW:


Hurricane won't eat the drone, will it? LOL!

i cant for the life of me figure out how they are going to do this. I have ran the aerodynamic numbers on this and if they get it in the outflow and it has more than a 25 - 30 kt component which most of them do they will not be able to control it. so yeah it will eat it. this is going to be interesting to say the least.
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525. BA
Quoting StormChaser81:


You can find every resource they offer on the internet for free. Might not be as nice, but same stuff.


send me a private message with free links to the ECMWF data they have...that is what I'm most interested in and I haven't been able to find it anywhere else, I generally only subscribe during the official hurricane season since I live on the coast and I like to look at as much info as I can, I've liked JB since back in his "free" days
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Quoting WaterWitch11:
my opinion:

slowish start to the hurricane season has given some folks a sense that it will continue this way. august & september will bring a freight train of storms.

True. This will make the average joe complacent. It only takes one major!
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Quoting StormChaser81:


You can find every resource they offer on the internet for free. Might not be as nice, but same stuff.



Do you have an accuweather pro account? If not, how would you know what they offer?
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Quoting StormW:


Guess it gives the tornado something to play with...kind of amusing it! LOL!!


This year he added air cannons to his intercept vehicle. Shot probes directly into an EF3/EF4 tornado as it moved over him.
Member Since: August 26, 2006 Posts: 16 Comments: 4766
Quoting TexasHurricane:


hmmmmm, I don't think anyone said anything about wanting....


people hear or see what they want to hear or see, that way they can call people wishcasters
Member Since: March 10, 2010 Posts: 1 Comments: 7233
Quoting BA:


accuweather pro has a lot more resources than just JB, it is worth the cost imo, especially with all the model data (including the ecmwf now)

I pay here and for accuweather pro...in addition, I think JB is one of the best, simple as that :)

Hey where is that photo from, Pipeline, North Shore?
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517. Skyepony (Mod)
EarthlyDragonfly~ ACE is Accumulated Cyclone Energy. NOAA's way of rough measuring storms & seasons. It's done using the strength in kts every 6hrs of the storm's life. Size of storm isn't included in this..


vmax is estimated sustained wind speed in knots

So you can still have a weaker, longer lived storm have a higher ACE than a strong short lived storm. If a storm crosses into the next year the total is added back to the year it was born.

Had a few moments to look closer. As expected in this point in the season EPAC has more ACE than Atlantic but the number of storms Atl has had had me assuming the ATL ACE had been higher.

Maximum Wind Speed & ACE per storm (ATCF operational intensity estimates)
North Atlantic
Alex (85 ACE = 7.3725)
TD02 (30 ACE = 0.0)
Bonnie (whirl) (35 ACE = 0.49)
Colin (whirl) (35 ACE = 0.245)

Eastern Pacific
Agatha (40 ACE = 0.2825)
Blas (55 ACE = 2.715)
Celia (140 ACE = 25.4875 )
Darby (105 ACE = 10.3925)
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Quoting MiamiHurricanes09:
Here is what Drakoen was referencing to:

Here it is at 324 hours emerging off of Africa, as you can tell it already is a potent tropical storm.



By 384 hours it is a strong hurricane with 6 closed isobars and many hurricane force wind isobars. Also notice the tropical cyclone making landfall over the Yucatan.



384hrs from now the earth could have been hit by an asteroid rendering this post completely pointless...
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514. xcool
92L 57KTS IN 48HR
Member Since: September 26, 2009 Posts: 2 Comments: 15603
513. xcool
JLPR2 . wendy's chili mmmmm so good lol
Member Since: September 26, 2009 Posts: 2 Comments: 15603
Quoting Ascendant:


So let me get this straight...it sounds like you want there to be a lot of dangerous storms. Correct?


hmmmmm, I don't think anyone said anything about wanting....
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About JeffMasters

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.