CSU leaves their hurricane forecast unchanged; 92L and Colin's remains worth watching
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
Reader Comments
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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.
Thank you!!
TAZ.
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.
ok
but is he moving ?
could it be possible he can stall and miss that trof alltogether ?
He is moving.
I wish we had some more racoons around here...all we have are opossums (EWWWW)...
kind old
All we need to have is a closed LLC, and judging by the marked increase in organization the pass few hours that might happen soon.
Very very very stupid question. What does the next TWO mean.
mod could be reading the blog and just poofed them anyway, without being flagged.
It was to be exspected I enjoyed them, nice to take a break for 1 sec and enjoy the pics cause being new to this and learning can make your head spin lol BACK TO TROPICS!!
Thank you. I told you it was a stupid question. I appreciate all the knowledge you all share without getting frustrated at the guys like me that really don't know any thing.
000
WTNT42 KNHC 281454
TCDAT2
HURRICANE KATRINA DISCUSSION NUMBER 23
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 AM EDT SUN AUG 28 2005
THE AIR FORCE HURRICANE HUNTERS JUST MEASURED A 166 KT FLIGHT LEVEL
WIND IN THE NORTHEAST EYEWALL...WHICH REQUIRES AN ADDITIONAL UPWARD
ADJUSTMENT OF THE CURRENT INTENSITY TO 150 KT. A DROP IN THE EYE
GAVE A CENTRAL PRESSURE OF 907 MB. KATRINA IS COMPARABLE IN
INTENSITY TO HURRICANE CAMILLE OF 1969...ONLY LARGER. GPS
DROPSONDE DATA FROM THE NOAA G-IV MISSION EARLIER TODAY SHOWED
KATRINA'S INTENSE CYCLONIC CIRCULATION EXTENDING THROUGH THE 200 MB
LEVEL...WITH THE FLOW SPIRALING ANTICYLONICALLY OUTWARD IN A
WELL-DEVELOPED UPPER-LEVEL OUTFLOW PATTERN BEYOND A COUPLE HUNDRED
N MI FROM THE CENTER. FLUCTUATIONS IN STRENGTH...DUE TO INTERNAL
STRUCTURAL CHANGES...ARE LIKELY PRIOR TO LANDFALL. HURRICANES
RARELY SUSTAIN SUCH EXTREME WINDS FOR MUCH TIME. HOWEVER WE SEE
NO OBVIOUS LARGE-SCALE EFFECTS TO CAUSE A SUBSTANTIAL WEAKENING THE
SYSTEM...AND IT IS EXPECTED THAT THE HURRICANE WILL BE OF CATEGORY
4 OR 5 INTENSITY WHEN IT REACHES THE COAST.
THERE IS NO CHANGE TO THE TRACK FORECAST. KATRINA SHOULD GRADUALLY
TURN TOWARD THE NORTH...INTO A WEAKNESS IN THE SUBTROPICAL RIDGE
ASSOCIATED WITH A LARGE MID-LATITUDE CYCLONE OVER THE NORTHERN
UNITED STATES AND SOUTHERN CANADA. THE OFFICIAL FORECAST TRACK IS
ABOUT IN THE MIDDLE OF THE DYNAMICAL GUIDANCE MODELS...WHICH ARE
RATHER TIGHTLY CLUSTERED. RECALLING THAT THE AVERAGE NHC 24-HOUR
TRACK FORECAST ERROR IS ABOUT 80 N MI...THE ACTUAL LANDFALL POINT
COULD STILL BE ANYWHERE FROM SOUTHEASTERN LOUISIANA TO THE
MISSISSIPPI COAST. ALSO...WE MUST CONTINUE TO STRESS THAT THE
HURRICANE IS NOT JUST A POINT ON THE MAP...BECAUSE DESTRUCTIVE
WINDS...TORRENTIAL RAINS...STORM SURGE...AND DANGEROUS WAVES EXTEND
WELL AWAY FROM THE EYE. IT IS IMPOSSIBLE TO SPECIFY WHICH COUNTY
OR PARISH WILL EXPERIENCE THE WORST WEATHER.
THIS ADVISORY SHOWS AN ADDITIONAL EXPANSION OF THE WIND FIELD OVER
THE EASTERN SEMICIRCLE BASED ON AIRCRAFT AND SURFACE OBSERVATIONS.
HURRICANE FORCE WINDS ARE FORECAST TO SPREAD AT LEAST 150 N MI
INLAND ALONG THE PATH OF KATRINA. CONSULT INLAND WARNINGS ISSUED
BY NATIONAL WEATHER SERVICE FORECAST OFFICES.
FORECASTER PASCH
I don't see why you'r ticked off by it. Nearly all comments involving off topic pictures get removed because they do violate the rules of the road. I don't see what makes your case so special.
Anyway, 21Z CIMSS should be out soon. I'm curious to see how this:
and this:
change, mainly curious about 92L. Ex-Colin is already decent in both.
no red tonight yellow more likey
update
it will still be the same storm i think
and it's not like we got recon heading into a cat4 undergoing RI, ok?
same ch of that yes
NOGAPS brings the Tehuantepec low back into Mexico.
Since it is identifiable as the same circulation, it will keep the same name.
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