Tropical Storm ALETTA

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TROPICAL STORM ALETTA DISCUSSION NUMBER   8
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP012006
800 PM PDT SUN MAY 28 2006

AS WAS THE CASE EARLIER TODAY...THE CENTER OF THE TROPICAL CYCLONE IS
VERY DIFFICULT TO LOCATE USING GEOSYNCHRONOUS SATELLITE IMAGES.  THE
CURRENT POSITION IS BASED ON EXTRAPOLATION OF A SLOW NORTHWARD
MOTION AND A FAIR CENTER FIX OFF OF A RECENT...0051 UTC... SSM/I
IMAGE.  THE INITIAL MOTION ESTIMATE REMAINS 360/2.  DYNAMICAL MODELS
ARE IN GENERAL AGREEMENT ABOUT A GRADUAL TURN TOWARD THE WEST DURING
THE NEXT COUPLE OF DAYS.  EVEN THE GFDL HAS BACKED OFF FROM ITS
INSISTENT FORECAST OF A LANDFALL IN MEXICO...AND NOW SHOWS A TRACK
PARALLEL TO THE COAST.  A GRADUAL LEFT TURN IS ALSO CONSISTENT
WITH THE GLOBAL MODELS FORECASTS SHOWING THE BUILDING OF A WEAK
MID-LEVEL RIDGE ALONG ABOUT 20N LATITUDE BY 36-48 HOURS.   

THE CLOUD PATTERN IS QUITE POORLY ORGANIZED AT THE MOMENT.  THERE ARE
NO OBVIOUS BANDING FEATURES...AND DEEP CONVECTION HAS DIMINISHED IN
COVERAGE AND INTENSITY OVER THE PAST SEVERAL HOURS.  I CONSIDERED
DECREASING THE CURRENT INTENSITY...BUT THE SYSTEM IS PROBABLY
UNDERGOING THE USUAL DIURNAL DECREASE THAT WE OBSERVE DURING THE
EVENING HOURS.  VERTICAL SHEAR IS EXPECTED TO RELAX SOMEWHAT OVER
THE NEXT DAY OR SO...HENCE A SLIGHT INCREASE IN STRENGTH IS FORECAST
OVER THE 48 HOURS.  LATER IN THE PERIOD...ALETTA IS LIKELY TO ENTER
A REGION OF STRENGTHENING WEST-SOUTHWESTERLY FLOW AND THE SHEAR
COULD INCREASE TO MORE THAN 20 KT IN 2-3 DAYS...WHICH WOULD INHIBIT
ANY FURTHER STRENGTHENING. THE OFFICIAL INTENSITY FORECAST FOLLOWS
THE SHIPS GUIDANCE RATHER CLOSELY...HOWEVER THERE IS A DISTINCT
POSSIBILITY THAT THE INCREASING SHEAR COULD WEAKEN ALETTA MORE THAN
EXPECTED IN 3-5 DAYS.
 
FORECASTER PASCH
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      29/0300Z 16.0N 101.0W    40 KT
 12HR VT     29/1200Z 16.2N 101.0W    40 KT
 24HR VT     30/0000Z 16.5N 101.2W    45 KT
 36HR VT     30/1200Z 16.6N 101.5W    50 KT
 48HR VT     31/0000Z 16.6N 102.4W    50 KT
 72HR VT     01/0000Z 16.5N 104.0W    50 KT
 96HR VT     02/0000Z 16.5N 105.5W    50 KT
120HR VT     03/0000Z 16.5N 107.0W    45 KT
 
 
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