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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Is Grand Ridge Close enough?
Yes sir, about 15 miles north of Blountstown
Except for the heat and lack of rain (my area), I think we're enjoying the tropics so far.
I know, that'll change...
Will Have to remember to bring my Jacket!!
sigh...no one can answer that.
Have a good one!
Morning Storm.
Any chance of the NAO going negative soon?
Bored of this below average temperatures and rain, already.
The "pattern" is an ever changing phantom type of thing. Today it's this but tomorrow it might be that. Whether it's educated or not, any long range prediction should be considered a guess.
Asking when the next big one will strike Florida is about the same as asking when you'll have your next traffic accident.
Humidity is a glorious 96 percent -- temp 75 degrees, add 20 degrees to the 75 for how it feels when you are running....and at this hour -- it won't feel like I'm running 'cross the Sahara. In two hours - it will be like running cross Death Valley.
Wowza - great Roll Call in here this AM!!!!
(((Pottery)))
Feel like I got hit my a 2x4 ..... need coffee (coke)
Come on Dfly...that 2x4 would not phase you. i think more like a 4x4 for you. hehe nice this am in wcfl 75
Any waves? as in surfing? just curious, learning your waters and how the wind affects things
LOVE the way this guy writes:
Local surf report: AuraSurf/M.Weaver
As we found out last time just because the NHC puts a name on a bunch of clouds does not mean that a real storm is going to produce surf. This was never about Colin. Just that Colin was swept up in the same wave of energy crossing the Atlantic. So don't focus on whether he regenerates or not. The swell is set to arrive Friday am, still smallish but ridable and clean. The more solid swell will hit Saturday afternoon. The wind is supposed to be crankin offshore so that's cool. Check comoestaeso.com Thursday pm to see this swell arrive on the north coast of PR. Back here on the gulf it's flat as a lake and will stay that way.
Colorado State's (Bill Gray and Phil Klotzbach) predictions were updated yesterday, and they are unchanged with 18 named storms, 10 hurricanes, and 5 majors. So far there have been 3 named storms and 1 hurricane, which leaves 15 more named storms, 9 more hurricanes, and 5 majors still to come according to them. There is still plenty to suggest the peak of the season will be active, and that is yet to come.
Regeneration of Colin may not occur, but if it were to it would be tonight at the earliest, with it being more likely toward the weekend. It's still currently at a 40% chance to regenerate. Odds still greatly favor it going out to sea regardless of development.
The wave in the Caribbean, on the other hand, fell apart overnight and chances for development will likely be dropping, and may never develop.
Another area in the Central Atlantic could be worth watching over the weekend or next week, but the overall set up for storms doesn't improve until at or just after mid August.
Come on back vacationers...to Destin,FL. area!!!
Heck after Destin come on down to Orlando too!!!
No, you're absolutely correct. You're no troll; just stating facts.
Pretty area down there.
The Gulf will hopefully enjoy a season in the sun with no TCs Link
I wish.... My youngest daughter likes to play punch buggy but still doesnt understand all the rules that you must punch the person in the arm/ shoulder.. (she is 6) we where walking Im 6'6" and she is about 3 foot tall and I was facing here... (that would put her at a very precarious height compared to me) and WHAMMMmmmm I was doubled up in the Target parking lot.. Poor thing didnt understand but Im still feeling the "sensitivity" of the whole ordeal...
You guys have awesome beaches and community.. I love it up there!
Just give credit when credit is due.
The last significant one here(hurricane conditions), was Opal...in 1995.
It is a nice area.
storm you still in a coastal city?
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
647 AM EDT THU AUG 05 2010
PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI. STRONG CONVECTION TO THE NORTH OF THE LEEWARD ISLANDS ASSOCIATES WITH THE
REMNANTS OF TS COLIN AS IT INTERACTS WITH A TUTT LOW TO THE NORTH. THE TUTT CONTINUES TO RETROGRESS AS THE SUBEQUATORIAL RIDGE BUILDS
INTO THE EASTERN CARIBBEAN. THE RIDGE ALOFT WILL REACH MAXIMUM AMPLITUDE EARLY IN THE CYCLE...AND IT IS TO PERSIST INTO THE
WEEKEND. BUT LATE SUNDAY-MONDAY IT WILL BEGIN TO ERODE AS ANOTHER TUTT LOW APPROACHES FROM THE EAST.
AT LOW LEVELS A SOUTHEASTERLY FLOW ESTABLISHES ACROSS THE ISLAND CHAIN TO PUERTO RICO/USVI...AS THE REMNANT LOW TO THE NORTH AND A INDUCES AN INVERTED TROUGH ACROSS THE EASTERN CARIBBEAN. A SHORT WAVE RIDGE TO THE EAST WILL HELP SUSTAIN THIS FLOW FOR THE NEXT 36-48 HRS...WITH EASTERLIES TO SLOWLY ESTABLISH LATER IN THE WEEKEND. THE ENSUING FLOW WILL SUSTAIN MOIST FLUX CONVERGENCE ACROSS THE ISLAND CHAIN EARLY IN THE CYCLE...WITH PWS OF 40-50MM.
THIS SLOWLY ADVECTS ACROSS THE VIRGIN ISLANDS DURING THE EVENING HOURS TODAY...AND ACROSS PUERTO RICO ON FIRST LIGHT FRIDAY. HIGH
MOISTURE CONTENT IS TO PERSIST THROUGH MORNING HOURS ON SATURDAY WITH A GRADUAL DRYING TREND EXPECTED LATER ON THE DAY TO SUNDAY.
THE GFS INITIALLY KEEPS MOST ACTIVE CONVECTION OVER THE VIRGIN AND LEEWARD ISLES...WITH A GRADUAL INCREASE ACROSS PUERTO RICO BY
SATURDAY MORNING. BUT DURING THE SHORT RANGE MAXIMA ACROSS THE ISLANDS PEAK AT LESS THAN 20MM. THE ECMWF CONTINUES TO SHOW MEAGER
AMOUNTS...LESS THAN 05MM/DAY IN THE SHORT TO MEDIUM RANGE PERIOD. THE NAM...ALTHOUGH NOT AS EXPLOSIVE AS ON THE PREVIOUS CYCLES...REMAINS THE WETTEST...SHOWING MAXIMA OF 30-40MM TO
APPROACH FROM THE SOUTH LATE ON FRIDAY AND INTO SATURDAY MORNING. THE NAM TAKES A TWO PUNCH APPROACH...WITH THE REMNANT LOW TO THE
NORTH INDUCING AND INVERTED TROUGH OVER THE EASTERN CARIBBEAN...WHILE ALSO SUSTAINING AN ITCZ CONNECTION AS THE LOW PULLS TO THE NORTH. ALTHOUGH THIS AMOUNTS SEEM MORE REALISTIC THAN
WHAT THE NAM PREVIOUSLY SHOWED...IT REMAINS ON THE HIGH END OF THE SCALE...AND IT WILL BE HIGHLY DEPENDENT ON HOW LONG THE ITCZ CONNECTION LASTS. SO WORTHWHILE ONSIDERING...BUT DO NOT BET THE
HOUSE ON IT.
Hopefully their forecast remains true.
Excerpt:
THE LOW DEPICTED OVER THE GULF OF MEXICO IN THE MANUAL PROGS IS INTENDED TO BE A REFLECTION OF THE TAIL END OF THE FRONT ALONG THE ATLANTIC SEABOARD EARLY IN THE PERIOD BREAKING OFF AND DRIFTING WESTWARD...AND NOT NECESSARILY A TROPICAL FEATURE.
Uh... Ivan?
Former #1 for several weeks.
Here's to all the Blue Collar workers braving the heat/humidity. A blues tune~
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