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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Member Since: Posts: Comments:
Quoting FLdewey:
I don't think they're ignoring it. It's just a big glob of disorganized convection... kind of like Walmart on Sunday.


Absolutely, but its worthy of a mention!! I am not saying its anywhere close to developing just the fact that its there.
Member Since: Posts: Comments:
1457. Drakoen
Windsat reveals a possible circulation with the EATL wave West of 30W above 10N:

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1456. Becca36
Quoting aquak9:
First the exclamation point, then the minus sign.

It's simple, folks.

Voice of reason.
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1455. calder
Quoting jasoncoolman2010xx:


TROPICAL UPDATE BY JASON..MY NEW COOL VIDEO OF THE TROPICALS


lol...
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Honest to GOD, I'm sick and tired of this JFV crap!!!, Frankly those that complain and report him, if it is him, over& over have fed him and made him grow & quitely frankly I find just as aggravating as the so called JFV himself!! Please learn the only beast that thrive is the one you feed!!!
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1453. xcool


Member Since: September 26, 2009 Posts: 2 Comments: 15603
Quoting hatteraswind:
Can someone tell me how to get the google earth data showing the recons?


Open google earth, and click the link.....

Link
Member Since: Posts: Comments:
Quoting aquak9:
First the exclamation point, then the minus sign.

It's simple, folks.
Yeah, I wish, people apparently like to deal with him since they keep quoting and interacting with him instead of just reporting and hitting the minus sign.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
1450. xcool
Drakoen /strong wave ???
Member Since: September 26, 2009 Posts: 2 Comments: 15603
Quoting thelmores:


negative.......


I guess negative!!!!!!!!!! ha!! I dont have a GPS but going out into the GOM and Colin do not seem to mix!! I guess I been sitting here in this double wide way too long!!
Member Since: July 8, 2010 Posts: 0 Comments: 345
1447. Drakoen
Quoting aquak9:
First the exclamation point, then the minus sign.

It's simple, folks.


Yup
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Quoting FLdewey:
I don't think they're ignoring it. It's just a big glob of disorganized convection... kind of like Walmart on Sunday.
Looks promising for development though in the near future
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1444. aquak9
Quoting FLdewey:
I don't think they're ignoring it. It's just a big glob of disorganized convection... kind of like Walmart on Sunday.


you've obviously never been to my walmart at 11pm on a friday...
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1441. aquak9
First the exclamation point, then the minus sign.

It's simple, folks.
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Quoting CybrTeddy:
Go away JFV, no one cares about what you do with your.. curtains.
what name does JFV have now
Member Since: July 14, 2009 Posts: 0 Comments: 2990
Is it safe to say Good Night :)
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Quoting psuweathernewbie:
The hunters are going into ex-Colin tonight, that is who people are seeing southeast of LA in the GOM. They are heading for Colin.


negative.......
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1437. Drakoen
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Quoting CybrTeddy:
Go away JFV, no one cares about what you do with your.. curtains.



this re port him



he be gone this like the rest of his litte names
Member Since: May 21, 2006 Posts: 5089 Comments: 114054
1433. Drakoen
Quoting LongBeachNY:
I cant believe NHC is ignoring the Cape Verde wave!!!!

Are they seeing something we aren't?


Avila wrote the TWO
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I cant believe NHC is ignoring the Cape Verde wave!!!!

Are they seeing something we aren't?
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Go away JFV, no one cares about what you do with your.. curtains.
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1427. Vero1
000
NOUS42 KNHC 041430
WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
1030 AM EDT WED 04 AUGUST 2010
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
VALID 05/1100Z TO 06/1100Z AUGUST 2010
TCPOD NUMBER.....10-066

I. ATLANTIC REQUIREMENTS
1. REMNANTS OF TROPICAL STORM COLIN
FLIGHT ONE -- TEAL 71
A. 05/1800Z
B. AFXXX 0204A COLIN
C. 05/1630Z
D. 23.0N 67.0W
E. 05/1730Z TO 05/2130Z
F. SFC TO 15,000 FT

2. SUCCEEDING DAY OUTLOOK:
A. A 06/1800Z FIX ON COLIN IF STILL A VIABLE
SYSTEM NEAR 27.0N 69.0W.
B. A POSSIBLE LOW LEVEL INVEST AT 06/1500Z
NEAR 16.5N 84.5W.

II. PACIFIC REQUIREMENTS
1. NEGATIVE RECONNAISSANCE REQUIREMENTS.
2. SUCCEEDING DAY OUTLOOK.....NEGATIVE.
JWP


Member Since: July 21, 2008 Posts: 4 Comments: 2233
Isn't the Cape Verde wave a little to far off to be affected by this trough and become a fish or is there another trough coming after by the time the wave reaches closer to the Antilles?
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1424. Ron5244
Quoting JupiterFL:


You obviously have no idea how to handle yourself. Show some respect. Not everyone on here is equal in their abilities when it comes to speaking, weather or whatever the discussion may be about.


Wise words from the humanitarian.
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Can someone tell me how to get the google earth data showing the recons?
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Quoting Orcasystems:


Yup.. just zig zagging along




Reminds me of my attempts at golf, left side, right side, left side....
Member Since: September 23, 2005 Posts: 13 Comments: 10466
Quoting Ron5244:


I'd prefer English...


You obviously have no idea how to handle yourself. Show some respect. Not everyone on here is equal in their abilities when it comes to speaking, weather or whatever the discussion may be about.
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Quoting HadesGodWyvern:
National Hurricane Center
Tropical Cyclone Outlook
0:00 AM UTC August 5 2010
=================================

Radar data from Mexico and satellite imagery indicates that the area of low pressure located 85 miles south southwest of Puerto Angel has become better organized this afternoon. Conditions are conducive for additional development and this system could become a tropical depression at any time tonight or Thursday.

Interest along the southern coast of Mexico should monitor the progress of this system.

Tropical Cyclone Formation Potential
=====================================
There is a HIGH chance of this disturbance to form into a significant tropical cyclone within the next 48 hours


---
Taz it was orange at 1800 UTC.



oh
Member Since: May 21, 2006 Posts: 5089 Comments: 114054
Quoting Vero1:


It appears to be just Flying in the Gulf.


Yup.. just zig zagging along


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1414. xcool
Member Since: September 26, 2009 Posts: 2 Comments: 15603
Quoting stormpetrol:
wait til 92L explodes later tonight or in the morning hours.


that is what Im thinking..!!!
Member Since: July 8, 2010 Posts: 0 Comments: 345

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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.