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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Quoting BDAwx:
ok.
1. This is weather. You should NEVER say that something will or wont do something. There is always the chance that it does something different to what you say. Even if you have all the model support in the world, or observational support in the world. That chance is always there.
2. Can we people please stop being rude? seriously?please?
3. Can we please use grammar that is vaguely understandable?
4. Finally, can we please not state opinions as fact then tack on "imo" or "jmo" on the end?

[+], BDA, and how r u? I see u may be getting some stormy wx this weekend.... if the forecasts are on track....
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Quoting AllStar17:
Where are the Hurricane Hunters at? Google Earth has them barely taking off.

Also, expect TD Seven-E in the EPAC tonight at 11.

This is only the tip of the iceberg in terms of tropical activity (especially for the Atlantic).


my google earth has them a ways out into the GOM heading east towards south central florida
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Quoting nrtiwlnvragn:


There is also a PREDICT website, and some information in the Hurricane Research Division 2010 plan. All are coordinating together. Will be something to have up to five planes in/around a storm.

Is that the same thing as (get a) GRIP which Pat posted?
Member Since: July 11, 2006 Posts: 14 Comments: 11173
Quoting IKE:


I forgot about them. Sorry.

Corrected to add #2....

(1)Bermuda.
(2)Canadian Maritime.
(3)This blog.




Mellower crowd in the early am!


Wat? I am in Canadian Maritime's! In Halifax to be exact? I thought it died? Should I be watching again?
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Quoting reedzone:


She left the blog, people kept attacking her for NO REASON. She also just got into the weather, now according to her last post, she doesn't wanna have the interest anymore.. Good job blogger, lost another one, way to go!


Who left?
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Where are the Hurricane Hunters at? Google Earth has them barely taking off.

Also, expect TD Seven-E in the EPAC tonight at 11.

This is only the tip of the iceberg in terms of tropical activity (especially for the Atlantic).
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Good evening. I see they bumped up ex-Colin from 20% to 40%. It could regenerate by this time tomorrow IMO.
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1698. Patrap
WunderBlogs - Standards
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Quoting BenBIogger:
Very interesting wave at 10W.


no kidding.
Member Since: July 11, 2006 Posts: 14 Comments: 11173
Quoting AstroHurricane001:


Some auroras are possible tonight after a series of four coronal mass ejections aimed directly at Earth.



The sun's setting just now, wonder if I'll see any auroras here in Southern Ontario.

Link
Link
Link
These CMIs might trigger one or more large earthquake(s) in the coming days and weeks. One just occured today as a matter of fact.
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Quoting Goldenblack:
c'mon Reed....you know we regulars think you analyze well. there are always attacks on here....just keep posting....at least you know they are paying attention and reading.



this is true
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Quoting Ossqss:


Thanks, no wonder I could not find it. They called it PREDICT (Pre-Depression Investigation of Cloud Systems in the Tropics) in the other articles. Acronym's, and not a very good one at that :)


There is also a PREDICT website, and some information in the Hurricane Research Division 2010 plan. All are coordinating together. Will be something to have up to five planes in/around a storm.
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flsky, looks like it might be a pretty strong storm near Crystal River on the other side of the state.
Or maybe it's the aurora borealis from the recent sun storm. You should see that in the western sky, I think.
I can't see anything west, north or south as I'm in an oak canopy. My eastern sky is fairly clear though.
Member Since: July 11, 2006 Posts: 14 Comments: 11173
Quoting IKE:


I forgot about them. Sorry.

Corrected to add #2....

(1)Bermuda.
(2)Canadian Maritime.
(3)This blog.




Mellower crowd in the early am!
Last storm they had up there was Hurricane John or something, right? They got some big waves.

And of course the a.m. crowd is mellower.... more coffee.... lol
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Quoting gator23:
1662. gator23
This comment has been censored for violating the Community Standards of this humorless blog.

You got that right! (There are some notable exceptions; you know who you are!)
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Gator, LOL sorry man
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c'mon Reed....you know we regulars think you analyze well. there are always attacks on here....just keep posting....at least you know they are paying attention and reading.

Quoting reedzone:


Apparently I get attacked the most because I'm posting facts and maps to back up my theory. While people like fallinstorms and hurrikat get nothing, not attacks. NOw a new member was scrutinized on this blog for just making peace. What the heck is wrong with you guys?? (not directed to the person I'm quoting).
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Quoting bappit:

Only see an ULL in the extreme NW Caribbean on this map. Dunno about the pressures. Surface winds look light.
Thanks for the reply.. Was looking at the GOM AVN on this site. You can easily see the ULL that is on your map but it looks as if it has moved into the GOM. I guess the other thing I am seeing is just high pressure swirling around? I still dont know what is up with those yellow dashed lines on the fronts?
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Very interesting wave at 10W.

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Quoting Ron5244:


Wise words from the humanitarian.


Sit back and read and learn...who is respected and liked on this blog (Taz) and those who cause nothing but problems.
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Quoting BDAwx:
ok.
1. This is weather. You should NEVER say that something will or wont do something. There is always the chance that it does something different to what you say. Even if you have all the model support in the world, or observational support in the world. That chance is always there.
2. Can we people please stop being rude? seriously?please?
3. Can we please use grammar that is vaguely understandable?
4. Finally, can we please not state opinions as fact then tack on "imo" or "jmo" on the end?



Apparently I get attacked the most because I'm posting facts and maps to back up my theory. While people like fallinstorms and hurrikat get nothing, not attacks. NOw a new member was scrutinized on this blog for just making peace. What the heck is wrong with you guys?? (not directed to the person I'm quoting).
Member Since: Posts: Comments:
1677. oakland
Quoting bappit:

Once a long time ago I was south of Baton Rouge and around 10 PM along the northwest horizon I could see lightning and clouds of a squall line in western Louisiana. It lasted just a couple of minutes. I think the effect is called looming.


Thanks for the insight. If I'm wrong, my apologies to flsky.
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Jennifer, if you are still out there: I feel for you on the attacks, however, you have to have some thick skin and persistence to be commenting on here. Reed is a good forecaster here and he still gets attacked. I get mostly ignored, and even some of the most respected knowledgeable people like Levi occasionally get harassed....just part of the deal

Quoting JenniferGirl:
I'm leaving and I'm never coming back. It's been two days since my interest in weather began, but now I know that can obviously never be since I get attacked.

I have a very low knowledge of tropical systems, and was hoping to gain it here with the Florida hurricane question.

Seeing as I have been blocked by everyone, it's a mistake to be here too.

To the 1 or 2 people who can see this, I'm sorry, and I am not JFV.
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1673. will45
Quoting Goldenblack:
Thanks will, that even is down from where he was....but I think the next fix will be slower



yes i agree he might have slowed down some more
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Yep... Colin 2.0 looking better now!

In fact, the nocturnal trinity of AOI's north and east of the Leeward Islands is something awesome to behold.




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Quoting crashingwaves:
Looks like Colin may regenerate in to a storm by the end of the week. Thats if the storm enters in favorable conditions. Then the questions is will the trough move it out to sea. Any takes on this.


out to sea like one of original forecasts... I think...
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1670. Ossqss
Quoting nrtiwlnvragn:


There is the GRIP website.


Thanks, no wonder I could not find it. They called it PREDICT (Pre-Depression Investigation of Cloud Systems in the Tropics) in the other articles. Acronym's, and not a very good one at that :)
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1669. bappit
Quoting flsky:
Off topic - I'm in Daytona Beach Shores facing WSW and I can see lightning associated w/a thunderstorm that is just now entering the Gulf. Amazing! I love Florida!!

Once a long time ago I was south of Baton Rouge and around 10 PM along the northwest horizon I could see lightning and clouds of a squall line in western Louisiana. It lasted just a couple of minutes. I think the effect is called looming.
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1668. BDAwx
ok.
1. This is weather. You should NEVER say that something will or wont do something. There is always the chance that it does something different to what you say. Even if you have all the model support in the world, or observational support in the world. That chance is always there.
2. Can we people please stop being rude? seriously?please?
3. Can we please use grammar that is vaguely understandable?
4. Finally, can we please not state opinions as fact then tack on "imo" or "jmo" on the end?

Member Since: Posts: Comments:
Looks like Colin may regenerate in to a storm by the end of the week. Thats if the storm enters in favorable conditions. Then the questions is will the trough move it out to sea. Any takes on this.
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Quoting oakland:


If you live in the Daytona area I don't doubt you are seeing lightning but seriously doubt it is associated with a thunderstorm entering the Gulf which is on the opposite side of the state.


I live in Palm Coast, I see nothing out there
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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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