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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1962. xcool
Member Since: September 26, 2009 Posts: 2 Comments: 15684
1961. leo305
what a monstrous amount of convection in the Central Atlantic
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1960. angiest
Quoting tkeith:


that thing has to have 40 lbs of tail meat...

He would feed alot of Cajuns


Dunnol about crocs, but gators are good eatin'. :)
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Quoting aquak9:
Baha- I posted them in your blog for you!! :) and they're in Skye's blog, and emmy's blog, too. At least THEY liked them, hahahah
LOL.... I did not look! I'll run there now. [Just proof that I did not, in fact, update my blog today.... lol lol]
Member Since: October 25, 2005 Posts: 19 Comments: 22322
Quoting BahaHurican:
What, again??? Rough sailing on this one, with the forecast not clear on how far west Colin will get before it scoots off to the north...



Yep - every week - back and forth between Jax and PR. It's a shuttle cargo run. Hopefully they are watching this thing too - but their route looks right into it for now...
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1957. 7544
what time does the hh go for colin ?
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1955. 7544
Quoting 2010StormNames:
Teddy, is that wave eventually expected to threaten Florida?


another fish
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1954. KEEPEROFTHEGATE (Mod)
Quoting pottery:
Good Evening...
First evening in a long time when I can see the Stars in a Clear sky.

Probably a Sign that all is well with Ebony, our Black Lab, who we put down today.
She was a Good Companion for 13 years, and will be truly missed.
Wife is Sad, so I am in Comforting Mode.

Keep well, All.
pottery my brother from another mother i sent to you something to take the pain from another

No More Tears
The time has come for the tears to end
for you to be happy and cheerful again.
I am safe in God's home above
cradled in His arms; covered with His love.


We run and play by the Bridge all day
waiting for the day when you'll be here to stay.
You've been crying so much I feel bad
I want you to be happy and not so sad.


Remember the time when I was so small
I couldn't even pickup the rubber ball.
I fought that ball from morning to night
it made you laugh, I was quite a sight.


Remember teaching me sit and stay
we had such fun since I didn't really obey.
but you kept at it with test after test.


Remember the great times we had in the past
like when we walked to the park we had a blast.
We'd run and play all through the park
until the sun went down and it got dark.


Remember the times we went for a ride
I was so excited I'd jump right inside.
Away we went to who knows where
but you and I we didn't really care.


I'll always love you, you're my best friend
I'll be right with you even to the end.
Always remember the great times we had
and there will be no reason to ever be sad.

Written by John Quealy

Member Since: July 15, 2006 Posts: 174 Comments: 54367
Is anyone else having a hard time getting recon data?
Member Since: Posts: Comments:
Quoting BDAwx:


I noticed that dry times in Bermuda during the hurricane season indicate a greater risk for Landfalls in the US. I think its because the Bermuda-Azores high is farther west which steers storms into the US and also keeps us under high pressure. 2005 + 2008 had dry summers here. Interesting stuff. :)
This makes a lot of sense. I'm trying to remember the last genuinely rainy July here, without much success - I'm usually out of country during parts of July, and the trend has been towards dry and hot the last few summers. I keep wondering if rainy means increased troughiness and therefore a semi-permanent weakness in the area, thereby inducing the commencement of storm recurviture around the high in our vicinity. I haven't done the research on it, though.
Member Since: October 25, 2005 Posts: 19 Comments: 22322
Impressive wave with model support. ECMWF, CMC, GFS, NOGAPS. CMC and NOGAPS are later to develop it (as it heads towards the Caribbean) ECMWF and GFS develop it in 48 hours.

Member Since: Posts: Comments:
1946. 7544
wow to the huge wave at 30 is it north enough to develope looks like 93l anytime now
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1945. amd
Quoting tropicfreak:
what do you think of colin by 2 am?? 50%??


If the IR2 tropical floater is any indication, probably at or below 40%. I know the best track has the system at 20.2 N 62.8W, but from the IR2, IMO, the center seems to be near 20 N and 65 W. My evidence is the w to nw winds currently being reported in san juan, and the flow of clouds around colin. IMO, Colin is still heavily sheared.

IR2 for Colin
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Quoting watchingnva:


agreed completely!!!


some pretty close lightning here.
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To bad we can't get a visible image of colin, that could help quite a bit
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1942. aquak9
Baha- I posted them in your blog for you!! :) and they're in Skye's blog, and emmy's blog, too. At least THEY liked them, hahahah
Member Since: August 13, 2005 Posts: 166 Comments: 26050
1941. tkeith
Quoting AussieStorm:

Croc's are territorial. could not be relocated. it was shot cause it was killing cattle and even chasing people in the town.
Boudreaux would relocate him to a grill....
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That CATL wave could be a major hurricane in the making... wow
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Quoting Orcasystems:


Go read 339 that SWMBO just posted in my blog...I hurt myself... and its a clean joke.


LOL -- but 341 was even funnier!
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Quoting robj144:


Why did they shoot it? They don't relocate them?

Croc's are territorial. could not be relocated. it was shot cause it was killing cattle and even chasing people in the town.
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what do you think of colin by 2 am?? 50%??
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Wow, that's one big wave at 9N 32W. Maybe part of the ITCZ, but still.

If Dr. Gray's and TSR's predictions hold, we are in for one huge Aug and Sept and maybe Oct as well.
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Quoting pottery:
Good Evening...
First evening in a long time when I can see the Stars in a Clear sky.

Probably a Sign that all is well with Ebony, our Black Lab, who we put down today.
She was a Good Companion for 13 years, and will be truly missed.
Wife is Sad, so I am in Comforting Mode.

Keep well, All.

So Sorry. We have many close calls with our 13 1/2 year old dal. Not at all looking forward to the day . Best wishes.
Member Since: Posts: Comments:
Quoting pottery:
Good Evening...
First evening in a long time when I can see the Stars in a Clear sky.

Probably a Sign that all is well with Ebony, our Black Lab, who we put down today.
She was a Good Companion for 13 years, and will be truly missed.
Wife is Sad, so I am in Comforting Mode.

Keep well, All.
Sorry to hear about your Lab, Pottery. This year has been pretty hard on pooches' owners... :o(

Quoting MiamiHurricanes09:
aquak9,

Hey! I saw the raccoon pictures! LOL, it was pretty cool.
I still haven't seen them! Where did u put them, again?

Quoting pvbeachbum:


And Ex-Colin sure looks like a good circulation on the pics I've seen posted here lately!

Unfortunately, my husband's ship is heading down into it again on their way to PR - they are currently east of the Bahamas and Miami...
What, again??? Rough sailing on this one, with the forecast not clear on how far west Colin will get before it scoots off to the north...

Member Since: October 25, 2005 Posts: 19 Comments: 22322
Quoting 7544:
no one keeping tabs on the recon


Its untasked and not doing much... I think its doing some Oil recon.
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1929. aquak9
Quoting JupiterFL:


Without humor this blog would pretty much be the worst experience ever.



Amen to that.
Member Since: August 13, 2005 Posts: 166 Comments: 26050
1928. BDAwx
Quoting BahaHurican:
I've been speculating about this, and wondering if the lower than average pressure in the area is causing stronger easterlies. But I'm not seeing huge amounts of evidence to support that. I do know we've been in the vicinity of either a passing trough or the TUTT zone for most of July, making it rainier than usual here. I guess that's kept it cool. I suspect it will be much hotter - more like normal - during the rest of Aug-Sep-Oct....


I noticed that dry times in Bermuda during the hurricane season indicate a greater risk for Landfalls in the US. I think its because the Bermuda-Azores high is farther west which steers storms into the US and also keeps us under high pressure. 2005 + 2008 had dry summers here. Interesting stuff. :)
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1927. 7544
no one keeping tabs on the recon
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Quoting Orcasystems:


Go read 339 that SWMBO just posted in my blog...I hurt myself... and its a clean joke.


Classic.
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1923. tkeith
Quoting robj144:


Why did they shoot it? They don't relocate them?


that thing has to have 40 lbs of tail meat...

He would feed alot of Cajuns
Member Since: Posts: Comments:
1921. OneDrop
Quoting pottery:
Good Evening...
First evening in a long time when I can see the Stars in a Clear sky.

Probably a Sign that all is well with Ebony, our Black Lab, who we put down today.
She was a Good Companion for 13 years, and will be truly missed.
Wife is Sad, so I am in Comforting Mode.

Keep well, All.

Sorry for your loss. It's ironic, just this morning I was just thinking about how my Weimeraner looks so old all of the sudden and she is 13 as well. The clear skies all of the sudden....strange how those things happen. A sure sign all is well!!
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Quoting robj144:


Why did they shoot it? They don't relocate them?


Thats a heck of a lot of shoes and belts to simply relocate.
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Quoting JupiterFL:


Without humor this blog would pretty much be the worst experience ever.


Go read 339 that SWMBO just posted in my blog...I hurt myself... and its a clean joke.
Member Since: Posts: Comments:
Any idea where recon. is? Google Earth has not updated in forever.
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1917. xcool
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Hey guys just got on, what in the world is that massive wave in the CATL
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Quoting aquak9:
hi jupiter, no not pot-stirring. Not at all. If I can't add something weather-related, or at least a little humorous, I usually just lurk.
Water puppy pot stirring? NEVER!!! cup stirring? Maybe mixed drink stirring? usually but pot stirring? NEVER....LOL
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1914. SWMIWX
Been here since 6/?/06. I just started this account. My other got hacked.
Member Since: Posts: Comments:
Quoting pottery:
Good Evening...
First evening in a long time when I can see the Stars in a Clear sky.

Probably a Sign that all is well with Ebony, our Black Lab, who we put down today.
She was a Good Companion for 13 years, and will be truly missed.
Wife is Sad, so I am in Comforting Mode.

Keep well, All.


So sorry.
Member Since: Posts: Comments:
1912. robj144
Quoting AussieStorm:

It's a croc not a gator That one was eating cows and goats before it was caught and shot. By there is another 1 similar size out and about up in the top end.


Why did they shoot it? They don't relocate them?
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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.