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 wdtcnewsonlinewx:
Is there any chance that the trough will not fully recurve Colin out to sea?
thats exactly what i am thinking
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Quoting xcool:


TAZ.



ok
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Quoting ho77yw00d:


Thanks for sharing you got nice close ups.. I havent seen a racoon for awhile so Thanks for reminding me what they look like lol


glad you got to see, it, POOF they removed it. Ah well.

Thanks for the minuses, you guys, I did ask for a certain amount of leniancy.

P'EHhhh on all of you.
Member Since: August 13, 2005 Posts: 169 Comments: 26126
Is there any chance that the trough will not fully recurve Colin out to sea?
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858. xcool


TAZ.
Member Since: September 26, 2009 Posts: 2 Comments: 15684
857. srada
Quoting Levi32:


At this point it probably will if the eastern center becomes dominant, which it looks like it's doing. If the western center proves stubborn then there's still a slight chance it comes west, but because it fell apart yesterday, the energy to the north was allowed to weaken the ridge and thus it looks like it's going to recurve. If it had stayed a strengthening tropical cyclone, it would be all wrapped around just northeast of Puerto Rico heading WNW and possibly threatening the US, but things changed when it fell apart yesterday.


Thank you!!
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Quoting Jeff9641:


That doesn't appear to be the case.

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSONVILLE FL
255 PM EDT WED AUG 4 2010


LONG TERM...SUNDAY THROUGH WEDNESDAY
WEAK FRONT TO SLOWLY SAG SOUTH ACROSS THE JAX CWA SUNDAY AND
MONDAY. UPPER TROUGH IS PROGGED BY THE GFS TO CLOSE OFF JUST
NORTH OF THE BAHAMAS AS UPPER RIDGE STRENGTHENS OVER THE PLAINS.
THE CANADIAN GEM ACTUALLY CUTS THE UPPER LOW OFF OVER NORTHERN
FLORIDA...WHICH WOULD RESULT IN A RATHER SOGGY SCENARIO FOR
THE LOCAL FORECAST AREA SUNDAY AND MONDAY.
BOTH MODELS STALL THE
FRONT SOMEWHERE OVER NORTHEAST FLORIDA WITH A WEAK CIRCULATION
DEVELOPING AT THE SURFACE. WILL BUMP POPS UP 10 PERCENT FOR AN
AVERAGE OF AROUND 50 PERCENT ACROSS THE ENTIRE CWA ON SUNDAY. WILL
DO THE SAME ON MONDAY BUT ONLY IN NORTHEAST FLORIDA. DRIER AIR
BEHIND THE FRONT SHOULD KEEP POPS A LITTLE LOWER ACROSS SOUTHEAST
GEORGIA BUT THIS WILL BE DEPENDENT UPON HOW FAR SOUTH THE FRONT
PROGRESSES BEFORE STALLING.
true but i would like to see new model runs on the new center developing
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look at 19.5N/61.5W , I think that could be a closed circulation! Colin might be back!
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Quoting aquak9:
ok, ya'll. The pretty ladies wanna see the raccoon, so no flagging, ok? I'll try to keep it weather-related.

We've got a little waterfall, but the pump broke. Didn't realize RocketRaccoon was a visitor, till he showed up almost begging. Brought him water, and obviously KizzieMae (white cat in the background) is used to helping out her fellow furry friends.





It is funny you posted these pictures brings back a funny memory. I am dating this girl in Texas that I met at a bowling Tournament in New Orleans. I flew to see her for Thanksgiving and later that night we are bsing at the table and her comes walking in but a raccoon. I jumped up and ran till they told me that she was their pet. These people were crazy LOL.
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852. xcool
'
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting aquak9:
ok, ya'll. The pretty ladies wanna see the raccoon, so no flagging, ok? I'll try to keep it weather-related.

We've got a little waterfall, but the pump broke. Didn't realize RocketRaccoon was a visitor, till he showed up almost begging. Brought him water, and obviously KizzieMae (white cat in the background) is used to helping out her fellow furry friends.





Thanks for sharing you got nice close ups.. I havent seen a racoon for awhile so Thanks for reminding me what they look like lol
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Quoting nolacane2009:


Thank you very much.



welcome
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Storm W one of the points made by everyone before season began was storms were going to impact the United States.So far they all move west into Mexico or out to sea,will this continue to be the case?
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847. DDR
Quoting KEEPEROFTHEGATE:
AOI/XX/XL
MARK
9.11N/46.23W

You can bet ill be watchign this one
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Quoting srada:


Hi Levi

Do you think this storm will miss the east coast all together?


At this point it probably will if the eastern center becomes dominant, which it looks like it's doing. If the western center proves stubborn then there's still a slight chance it comes west, but because it fell apart yesterday, the energy to the north was allowed to weaken the ridge and thus it looks like it's going to recurve. If it had stayed a strengthening tropical cyclone, it would be all wrapped around just northeast of Puerto Rico heading WNW and possibly threatening the US, but things changed when it fell apart yesterday.
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Quoting tatoprweather:


where?



read my post a little better bfor posting what did i say in my post it starts with I THINK
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Quoting Tazmanian:



there is no more advisory on this storm the rest is being follow on the two and the next two comes out at 8pm


Thank you very much.
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Quoting nyhurricaneboy:
Evening all.

Wonder how Colin will turn out. We could see regeneration as soon as tomorrow, IMO.

Anyway, I have some important info to share with those of you who want to help get rid of trolls on this blog and, thus, facilitate tropical discussion that is the purpose of this blog and what used to occur. I will be in the Shaun and Tim Chat Room until about 5:30 pm EDT. I am having a meeting regarding the recent chat issues. Please feel free to drop in with your ideas and concerns. Any input is greatly appreciated, and all ideas will be submitted directly to admin.
control JFV and some Individuals who only come on here to srat trouble and cause problems
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Quoting Tazmanian:
i think we will see 93 and 94L this week


where?
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ok, ya'll. The pretty ladies wanna see the raccoon, so no flagging, ok? I'll try to keep it weather-related.

We've got a little waterfall, but the pump broke. Didn't realize RocketRaccoon was a visitor, till he showed up almost begging. Brought him water, and obviously KizzieMae (white cat in the background) is used to helping out her fellow furry friends.



Member Since: August 13, 2005 Posts: 169 Comments: 26126
Evening all.

Wonder how Colin will turn out. We could see regeneration as soon as tomorrow, IMO.

Anyway, I have some important info to share with those of you who want to help get rid of trolls on this blog and, thus, facilitate tropical discussion that is the purpose of this blog and what used to occur. I will be in the Shaun and Tim Chat Room until about 5:30 pm EDT. I am having a meeting regarding the recent chat issues. Please feel free to drop in with your ideas and concerns. Any input is greatly appreciated, and all ideas will be submitted directly to admin.
Member Since: Posts: Comments:
Quoting nolacane2009:
When does the next advisory come out? Does anyone thing Colin will be upgraded to TS on that next advisory?



there is no more advisory on this storm the rest is being follow on the two and the next two comes out at 8pm
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INV/92/L
MARK
13.71N/74.48W
MOVEMENT W
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Quoting largeeyes:


I don't recall us having 99, 90 and 91. Am I wrong?


99L was designated inland in Mexico and was activated and deactivated in the same day.

90L was pre-Colin, but then they deactivated it, and then they activated it again as 91L the next day before it became TD 4, and then TS Colin.
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Quoting nolacane2009:
When does the next advisory come out? Does anyone thing Colin will be upgraded to TS on that next advisory?
there are no advisories its currently an area of low pressure
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Quoting largeeyes:
Will be interesting if the next invest is 99L or 93L, considering we skipped over 99-90-91


We did not skip 98L, 99L and 90L, 98L you know about, 99L was the inland circulation which 98L developed before moving inland just a few days later, because it was just inland and had a vigorous circulation, and 90L was the low pressure system in the ITCZ that got eaten by the tropical wave that developed into Tropical Storm Colin, which was 91L before then. 92L is in the Caribbean Sea now, so the next invest would be 93L.
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http://www.ssd.noaa.gov/goes/flt/t1/loop-vis.html
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When does the next advisory come out? Does anyone thing Colin will be upgraded to TS on that next advisory?
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04L/REM LOW
MARK
19.93N/62.56W
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BBL
Member Since: October 25, 2005 Posts: 19 Comments: 22357
Quoting Hurricanes101:


we didnt skip, they made a mistake by saying 98L but quickly changed it to 92L

the next invest should be 93L


I don't recall us having 99, 90 and 91. Am I wrong?
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AOI/XX/XL
MARK
9.11N/46.23W
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Quoting Hurricanes101:


I dont have access to the rammbdis pics of the East Atlantic, maybe someone else can post it though



ok
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if colin regenerates and stays weak would the trough miss it and continue towards the SE us Coast ??? just food for thought
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Quoting Tazmanian:



Hurricanes101 can you point out the area out by 30W that could be come 93L


I dont have access to the rammbdis pics of the East Atlantic, maybe someone else can post it though
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Ex Colin looking better this afternoon with the (convection injection). Will we see a new center and are the models picking up on this as far as direction is concerned?
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Quoting StormW:
Colin looking good!
afternoon storm, it appears colin is regenerating or trying real hard to looks like a sheared tropical storm
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Quoting Hurricanes101:
805. jasoncoolman2010xx 8:52 PM GMT on August 04, 2010

He didnt say we had 93L, he said we could have 93L out of the area by 30W



Hurricanes101 can you point out the area out by 30W that could be come 93L
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821. srada
Quoting Levi32:
Only problem with Colin strengthening later is that the GFS doesn't seem to initialize the 2nd center near Puerto Rico on the 850mb maps. With the GFS low resolution it's hard to say but it could give Colin more trouble if it can't concentrate the center in one spot, but we'll see.


Hi Levi

Do you think this storm will miss the east coast all together?
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Quoting largeeyes:
Will be interesting if the next invest is 99L or 93L, considering we skipped over 99-90-91


we didnt skip, they made a mistake by saying 98L but quickly changed it to 92L

the next invest should be 93L
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the low that sheared Colin is heading north. in the meantime...Colin is staying weak and heading just about west. in the water vapor imagery you can see the dry air is starting to close up and get moist. I am getting a funny feeling about Colin. Kinda an "andrew" type feeling...oh, I don't know...August...HOT....sst's...

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Quoting aquak9:
totally off-topic, but with all the heat, I've got a raccoon that keeps visiting for water and food. I have pics, but don't wanna get flagged.

Anyone wanna see the raccoon?

Sure!
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http://www.ssd.noaa.gov/goes/flt/t1/loop-vis.html

latest visible image of excolin
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Sure, let's see the racoon pics!
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814. xcool
jasoncoolman2010xx no 93L
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting aquak9:
totally off-topic, but with all the heat, I've got a raccoon that keeps visiting for water and food. I have pics, but don't wanna get flagged.

Anyone wanna see the raccoon?


I do =)
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Will be interesting if the next invest is 99L or 93L, considering we skipped over 99-90-91
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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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