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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2762. PRweathercenter
1:05 AM GMT on August 06, 2010
Member Since: July 21, 2010 Posts: 60 Comments: 1011
2761. Tazmanian
7:11 PM GMT on August 05, 2010
Quoting Thundercloud01221991:
***Off Topic Question**** Does anyone know what the sun symbol on ebay means ... ex (Link)


**** On Topic ****

Why isnt this a TS right now and when is recon supposed to get there?




plz stop with that you no vary well that the recone is in there
Member Since: May 21, 2006 Posts: 5089 Comments: 114041
2760. Thundercloud01221991
6:12 PM GMT on August 05, 2010
***Off Topic Question**** Does anyone know what the sun symbol on ebay means ... ex (Link)


**** On Topic ****

Why isnt this a TS right now and when is recon supposed to get there?
Member Since: August 1, 2006 Posts: 28 Comments: 3716
2759. kshipre1
2:51 PM GMT on August 05, 2010
I agree with TampaSpin. Storm is the ultimate professional and a great guy as well. Very accurate and always on the money!

We are happy you part of Weather Underground Storm! Thanks!

On a seperate note, the if the negative NAO puts Florida at more risk, then after August 10 to potentially October end, I will be watching the tropics very carefully.

Prerak
Member Since: July 12, 2010 Posts: 0 Comments: 1130
2758. hang10z
2:48 PM GMT on August 05, 2010
Good Morning Everyone, I really hope Old man willicker Colin will pump some North Swells down the coast of E FL... Its been awhile since I've gotten some overhead waves...

Lets hope it misses Bermuda

Member Since: August 2, 2010 Posts: 0 Comments: 34
2757. kshipre1
2:34 PM GMT on August 05, 2010
good morning Storm,

Great to see you as usual. quick question. with all the talk about potentially getting tropical storm Daniel next week, in your analysis, do you see this storm recurving out to sea similar to Colin?

What do the steering current look like? Another trough? Thanks as always
Member Since: July 12, 2010 Posts: 0 Comments: 1130
2756. Eaglesfan27
2:19 PM GMT on August 05, 2010
The weather here in Baton Rouge is turning very nasty very quickly with a strong line of storms moving in.
2755. jeffs713
2:16 PM GMT on August 05, 2010
Quoting sarahjola:
do you mean ull?:)

I was referring to StormW's RGB pic of ex-Colin, showing the LLC coming out from under cloudcover rather naked.
Member Since: August 3, 2008 Posts: 16 Comments: 5792
2754. sarahjola
2:11 PM GMT on August 05, 2010
blog died:(
Member Since: September 10, 2008 Posts: 0 Comments: 1291
2753. sarahjola
2:08 PM GMT on August 05, 2010
Quoting jeffs713:

Eye spy an LLC! (thats why Colin won't be upgraded)
do you mean ull?:)
Member Since: September 10, 2008 Posts: 0 Comments: 1291
2752. jeffs713
2:03 PM GMT on August 05, 2010
Quoting StormW:

Eye spy an LLC! (thats why Colin won't be upgraded)
Member Since: August 3, 2008 Posts: 16 Comments: 5792
2751. ShenValleyFlyFish
2:03 PM GMT on August 05, 2010
Quoting Orcasystems:


ROFLMAO, what did you spike your morning coffee with :)
45-7 = troublemaker
Member Since: September 9, 2007 Posts: 36 Comments: 4687
2750. SLU
2:01 PM GMT on August 05, 2010
The circulation of ex-Colin has become better defined but the convective organisation of the system is very poor this morning. The large rain band to the north of the system is actually moving away from the center and not trying to wrap into the circulation. Also there are outflow boundaries developing on the northern side. This suggests that the system is not strengthing at this time.

Member Since: July 13, 2006 Posts: 12 Comments: 4731
2749. viman
1:59 PM GMT on August 05, 2010
Quoting all4hurricanes:
Does anyone think COlin will be upgraded at 11?


Not with an exposed LLC it wont...
Member Since: August 12, 2007 Posts: 0 Comments: 375
2748. jazzygal
1:58 PM GMT on August 05, 2010
Quoting IKE:


And this is when this blog starts losing it again. WU needs a pay to enter on Dr. Masters blog and it would cut out a lot of the nonsense.


I agree!!
Member Since: June 2, 2008 Posts: 0 Comments: 204
2747. CoopsWife
1:58 PM GMT on August 05, 2010
Quoting Patrap:
..Yawwwnnnnnnnnnnnnnnn.


Yep, and I hope it stays this way. Be nice to snooze through the season, instead of just taking cat naps, wouldn't it?
Member Since: June 19, 2006 Posts: 63 Comments: 4175
2746. Patrap
1:58 PM GMT on August 05, 2010
er..


NEW BLOG.
Member Since: July 3, 2005 Posts: 414 Comments: 125468
2745. IKE
1:57 PM GMT on August 05, 2010
Member Since: June 9, 2005 Posts: 23 Comments: 37858
2744. poknsnok
1:57 PM GMT on August 05, 2010
nothing but fish this year
Member Since: August 17, 2008 Posts: 0 Comments: 222
2742. Drakoen
1:56 PM GMT on August 05, 2010
NEW TROPICAL STORM FORECAST TO DEVELOP AFTER 36 HOURS
FORECAST POSITION AT T+ 36 : 16.1N 33.3W

VERIFYING TIME POSITION STRENGTH TENDENCY
-------------- -------- -------- --------
12UTC 06.08.2010 16.1N 33.3W MODERATE
00UTC 07.08.2010 17.9N 34.1W MODERATE LITTLE CHANGE
12UTC 07.08.2010 19.8N 36.1W WEAK WEAKENING SLIGHTLY
00UTC 08.08.2010 BELOW TROPICAL STORM STRENGTH
Member Since: October 28, 2006 Posts: 57 Comments: 29714
2741. Neapolitan
1:55 PM GMT on August 05, 2010
As others have noted, Colin's vision won't improve until he can put his eye back into its socket:

Colin

Source
Member Since: November 8, 2009 Posts: 4 Comments: 13256
2740. Patrap
1:55 PM GMT on August 05, 2010
..Yawwwnnnnnnnnnnnnnnn.
Member Since: July 3, 2005 Posts: 414 Comments: 125468
2739. wunderkidcayman
1:54 PM GMT on August 05, 2010
Good morning guys I just woke up to see that both 92L and ex-colin is doing very well more so for 92L last night it looked bad and convectionless and now todat it looks good and also look to be moving WNW-NW I see it at 15.9N 78.2W
Member Since: June 13, 2009 Posts: 2 Comments: 9548
2738. SLU
1:54 PM GMT on August 05, 2010
weather457:

I'm weather 457 not 456


Very distasteful. You shall be R-E-P-O-R-T-E-D.
Member Since: July 13, 2006 Posts: 12 Comments: 4731
2737. Drakoen
1:51 PM GMT on August 05, 2010
Quoting Tropicsweatherpr:
Drakoen, what is your take on the Central Atlantic area?


The pouch associated with PGI24L is going to try to phase with the vorticity within the ITCZ possibly giving us Danielle. Upper level winds should be conducive for some development.
Member Since: October 28, 2006 Posts: 57 Comments: 29714
2736. Squid28
1:51 PM GMT on August 05, 2010
Quoting IKE:


And this is when this blog starts losing it again. WU needs a pay to enter on Dr. Masters blog and it would cut out a lot of the nonsense.


Until this year, my ignore list has always floated at around 12 handles (and I cleared it at the start of season). I have always tried to give everyone but the worst offenders a chance to be seen. I just checked and I am at 61 on the ole list as of now, otherwise I could not possibly even read the blog for wading through all the extra "stuff". Looks like it is time to bump the shield up another notch......
Member Since: May 23, 2006 Posts: 0 Comments: 343
2735. TampaSpin
1:51 PM GMT on August 05, 2010
Quoting sammywammybamy:


Lol StormW as Well as you said when were in Negative Nao, Florida and the CONUS will be at greater risk.

Last Hurricane to Hit the State of FL: 2005 Wilma
Last Tropical Storm: 2010 Bonnie (Although Very Weak)


I would say StormW is much smarter than me about this stuff as he is the total professional...and he probably beats me by a small margin on looks too.......LOL
Member Since: September 2, 2007 Posts: 177 Comments: 20430
2734. BahaHurican
1:50 PM GMT on August 05, 2010
Gotta go. See youse guys lata..
Member Since: October 25, 2005 Posts: 19 Comments: 20686
2732. MiamiHurricanes09
1:48 PM GMT on August 05, 2010
Quoting DaytonaBeachWatcher:


I dont think they will upgrade at 11 since they have recon going in this afternoon, I think they will wait for proof.
Yeah probably.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
2731. DaytonaBeachWatcher
1:47 PM GMT on August 05, 2010
Quoting MiamiHurricanes09:
Satellite imagery shows an evident well-defined surface circulation so if the NHC chooses they definitely could, but they very likely will wait for recon to investigate. We may see red at 2PM EDT though.


I dont think they will upgrade at 11 since they have recon going in this afternoon, I think they will wait for proof.
Member Since: June 29, 2007 Posts: 0 Comments: 1135
2730. wayfaringstranger
1:46 PM GMT on August 05, 2010
Quoting TampaSpin:
I thought i had an Imposter the other day. But, i was just having an out of body moment after too many beers at the game! Wife did the driving!


I had an imposter. Tom Cruise!

People mistake him for me all the time!

So not fair. Especially since he makes more $.
Member Since: July 12, 2010 Posts: 0 Comments: 235
2729. HarleyStormDude52
1:46 PM GMT on August 05, 2010
whats the latest on 92? Will there be any recon into it? looks like the models have not changed from yesterday
Member Since: July 8, 2010 Posts: 0 Comments: 345
2728. MiamiHurricanes09
1:45 PM GMT on August 05, 2010
Quoting all4hurricanes:
Does anyone think COlin will be upgraded at 11?
Satellite imagery shows an evident well-defined surface circulation so if the NHC chooses they definitely could, but they very likely will wait for recon to investigate. We may see red at 2PM EDT though.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
2727. BahaHurican
1:45 PM GMT on August 05, 2010
Ppple, 456 has posted on his blog this week, but not on the main. Also, 456 can spell and use capitals properly. 'Nuff said; don't get distracted - have another cuppa coffee....
Member Since: October 25, 2005 Posts: 19 Comments: 20686
2726. TampaSpin
1:45 PM GMT on August 05, 2010
I thought i had an Imposter the other day. But, i was just having an out of body moment after too many beers at the game! Wife did the driving!
Member Since: September 2, 2007 Posts: 177 Comments: 20430
2724. DaytonaBeachWatcher
1:45 PM GMT on August 05, 2010
Quoting weather457:

I'm weather 457 not 456


no kidding, but you stole his pic
Member Since: June 29, 2007 Posts: 0 Comments: 1135
2721. wayfaringstranger
1:44 PM GMT on August 05, 2010
Correction....when in doubt ask storm.
Member Since: July 12, 2010 Posts: 0 Comments: 235
2720. Hurricanes12
1:44 PM GMT on August 05, 2010
Quoting all4hurricanes:
Does anyone think COlin will be upgraded at 11?


It most likely wouldn't be upgraded until the HH's get out there. Bad thing is, it's being sheared a bit right now and it's circulation is ragged and may be exposed.
Member Since: June 21, 2010 Posts: 0 Comments: 528
2717. all4hurricanes
1:42 PM GMT on August 05, 2010
Does anyone think COlin will be upgraded at 11?
Member Since: March 29, 2008 Posts: 0 Comments: 2338
2716. wayfaringstranger
1:40 PM GMT on August 05, 2010
Quoting StormW:


I know, but folks ain't getting it.


LOL!

I know I know. Good morning my friend.

Member Since: July 12, 2010 Posts: 0 Comments: 235
2715. BahaHurican
1:40 PM GMT on August 05, 2010
Quoting Orcasystems:


ROFLMAO, what did you spike your morning coffee with :)
It's more of a hangover from last night....

BTW, do u guys see what I'm talking about w/ the ULLs?

Member Since: October 25, 2005 Posts: 19 Comments: 20686
2714. IKE
1:40 PM GMT on August 05, 2010
Quoting StormW:


Yeah IKE, it's not 456...There's no entries on the blog of 457.


And this is when this blog starts losing it again. WU needs a pay to enter on Dr. Masters blog and it would cut out a lot of the nonsense.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
2713. DaytonaBeachWatcher
1:40 PM GMT on August 05, 2010
Quoting StormW:


Yeah IKE, it's not 456...There's no entries on the blog of 457.


and 456's blog is still there, must be an imposter
Member Since: June 29, 2007 Posts: 0 Comments: 1135
2712. breald
1:40 PM GMT on August 05, 2010
Quoting Jeff9641:


Basically they said they expect an explosion in storms to occur over the next 2 weeks and one member from the NHC was on TWC last night and he said he really feels the US coast especially the SE US is for a big one or two down the road. Very ominious tone while listening to there discussions last night.


But it seems like it takes a month for a storm to form. We were tracking ex-Colin for weeks before it was decleared a TD.
Member Since: May 28, 2008 Posts: 38 Comments: 5303

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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.