Tropical Storm ERNESTO

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TROPICAL STORM ERNESTO DISCUSSION NUMBER   9
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL052006
500 PM EDT SAT AUG 26 2006
 
ON A MISSION THAT FEATURED A SATCOM FAILURE...AN AIR FORCE RESERVE
HURRICANE HUNTER AIRCRAFT REPORTED THAT THE CENTER OF ERNESTO WAS
WELL EAST-NORTHEAST OF THE INTERMEDIATE ADVISORY POSITION.  HOW
MUCH OF THIS IS DUE TO RE-FORMATION OF THE CENTER AND HOW MUCH IS
DUE TO AN ACTUAL TRACK CHANGE IS UNCLEAR.  THE AIRCRAFT REPORTED A
CENTRAL PRESSURE OF 997 MB...AND A DROPWINDSONDE NORTHEAST OF THE
CENTER SHOWED THAT THE MAXIMUM WINDS HAVE INCREASED TO AT LEAST 50
KT.  WHILE THE RE-FORMATION PUTS THE CENTER CLOSER TO THE
CONVECTION...ERNESTO IS STILL ENCOUNTERING NOTABLE WESTERLY TO
SOUTHWESTERLY VERTICAL WIND SHEAR.

THE INITIAL MOTION IS A VERY UNCERTAIN 295/11.  WHILE THE OVERALL
SYNOPTIC PATTERN IS UNCHANGED FROM THE PREVIOUS ADVISORY...THE
REFORMATION OF THE CENTER REQUIRES SHIFTING THE FIRST 72 HR OF THE
TRACK ABOUT 50 N MI NORTHEAST OF THE PREVIOUS TRACK.  THIS
INCREASES THE THREAT TO HAITI...THE DOMINICAN REPUBLIC...CUBA...AND
THE FLORIDA KEYS.  IT SHOULD BE NOTED THAT THE GFS SOLUTION OF
BRINGING THE LOW-LEVEL CENTER OF ERNESTO TO SOUTH FLORIDA LOOKS
DUBIOUS...AS THE 500 MB CENTER STAYS WELL TO THE SOUTH OVER CUBA. 
AFTER 72 HR...THE LARGE-SCALE MODELS ARE COMING INTO BETTER
AGREEMENT THAT THE MID-LEVEL RIDGE OVER THE GULF OF MEXICO WILL BE
BROKEN BY A SHORTWAVE TROUGH MOVING SOUTHEASTWARD FROM THE
MISSISSIPPI VALLEY INTO THE SOUTHEASTERN STATES.  THIS SHOULD ALLOW
ERNESTO TO TURN NORTHWARD OVER THE CENTRAL OR EASTERN GULF OF
MEXICO...ALTHOUGH THERE ARE STILL DIFFERENCES IN SPEED BETWEEN THE
SLOWER UKMET AND ECMWF AND THE FASTER NOGAPS.  THE LATTER PART OF
THE FORECAST TRACK CALLS FOR A GRADUAL TURN TOWARD THE NORTH AT A
SLOW SPEED...SIMILAR TO BUT EAST OF THE PREVIOUS FORECAST.  MORE
ADJUSTMENTS OF THE FORECAST TRACK MAY NECESSARY ON THE NEXT
ADVISORY DEPENDING ON ANY NEW JUMPS IN THE CENTER POSITION TONIGHT.
 
THE LARGE-SCALE MODELS CONTINUE TO FORECAST THE DEVELOPMENT OF A
LARGE UPPER-LEVEL ANTICYCLONE ALONG THE FORECAST TRACK...ALTHOUGH
SO FAR THEY HAVE BEEN TOO FAST IN DOING SO.  IF THE MODELS ARE
CORRECT...THE SHEAR SHOULD DIMINISH DURING THE NEXT 12-24 HR AND
ALLOW ERNESTO TO STRENGTHEN.  THE INTENSITY FORECAST CALLS FOR SLOW
STRENGTHENING DURING THE FIRST 24 HR...AND STEADY STRENGTHENING
THEREAFTER.  THE INTENSITY FORECAST CALLS FOR ERNESTO TO REACH 105
KT INTENSITY IN 120 HR...SLIGHTLY STRONGER THAN THE SHIPS MODEL...
AND THE STORM COULD GET STRONGER THAN THAT.  ONE POTENTIAL PROBLEM
WITH THE INTENSITY FORECAST IS INTERACTION WITH LAND...AS ERNESTO
MIGHT NOT STRENGTHEN AS MUCH AS FORECAST IF IT GETS TOO CLOSE TO
HISPANIOLA OR CUBA.
 
IN SUMMARY...ERNESTO COULD BECOME A POTENTIALLY DANGEROUS HURRICANE
AS IT MOVES ACROSS THE NORTHWESTERN CARIBBEAN SEA AND THE GULF OF
MEXICO. INTERESTS IN THESE AREAS SHOULD CLOSELY MONITOR THE
PROGRESS OF THIS SYSTEM.

 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      26/2100Z 15.9N  71.6W    50 KT
 12HR VT     27/0600Z 16.8N  73.3W    50 KT
 24HR VT     27/1800Z 18.1N  75.4W    60 KT
 36HR VT     28/0600Z 19.4N  77.6W    70 KT
 48HR VT     28/1800Z 20.8N  79.8W    80 KT
 72HR VT     29/1800Z 23.5N  83.5W    85 KT
 96HR VT     30/1800Z 25.5N  86.0W    95 KT
120HR VT     31/1800Z 28.0N  87.0W   105 KT
 
$$
FORECASTER BEVEN
 
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