Subtropical Storm ANDREA

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SUBTROPICAL STORM ANDREA DISCUSSION NUMBER   2
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL012007
500 PM EDT WED MAY 09 2007
 
THE ORGANIZATION OF ANDREA HAS DETERIORATED SOMEWHAT DURING THE PAST
FEW HOURS...WITH A SIGNIFICANT DECREASE IN CONVECTION PARTICULARLY
IN THE NORTHWESTERN QUADRANT. SOME BANDS OF DEEP CONVECTION
PERSIST...HOWEVER...ELSEWHERE IN THE CIRCULATION...AND SHIP WBVY
REPORTED 37 KT WINDS AT 18Z ABOUT 75 N MI NORTH-NORTHEAST OF THE
CIRCULATION CENTER. THE NEXT RECONNAISSANCE AIRCRAFT WILL
INVESTIGATE ANDREA TOMORROW MORNING...AND THE NEXT QUIKSCAT PASS
OVER OR NEAR ANDREA WILL OCCUR NEAR 00Z THIS EVENING. IN THE
MEANTIME...IT IS REASONABLE TO MAINTAIN THE INTENSITY AT 40 KT.
ANDREA IS CURRENTLY OVER SSTS NO WARMER THAN ABOUT 25 CELSIUS...AND
THE SLOW MOTION SHOWN IN THE TRACK FORECAST PROBABLY MEANS SOME
EVEN COOLER WATERS WILL BE CHURNED UP FROM BENEATH THE SURFACE.
THEREFORE...IN ACCORDANCE WITH ALL OF THE INTENSITY GUIDANCE...A
WEAKENING TREND IS ANTICIPATED AND THE OFFICIAL FORECAST SHOWS
DISSIPATION NEAR THE COAST IN LESS THAN FOUR DAYS.
 
THE SLOPPY CIRCULATION MAKES IT DIFFICULT TO CONFIDENTLY DETERMINE
THE INITIAL MOTION...BUT MY BEST ESTIMATE REMAINS SLOW AND
GENERALLY WESTWARD OR 265/4.  RECENT IMAGERY SUGGESTS THE
SYSTEM MIGHT HAVE STARTED SAGGING TOWARD THE SOUTHWEST.
THERE IS NO SIGNIFICANT CHANGE TO THE TRACK FORECAST OR THE
SUPPORTING REASONING.  SINCE ANDREA IS TRAPPED WITHIN A LARGE
MIDDLE- TO UPPER-LEVEL TROUGH THAT THE DYNAMICAL MODELS FORECAST TO
NOT MOVE MUCH DURING THE NEXT COUPLE OF DAYS...A SLOW AND GENERALLY
SOUTHWARD MOTION IS FORECAST.  BEYOND THAT TIME...SOME OF THE
MODELS FORECAST THE LOW-LEVEL CIRCULATION TO DECOUPLE FROM THE
DECAYING MIDDLE- AND UPPER-LEVEL VORTICITY MAXIMA...SO THE OFFICIAL
FORECAST INDICATES A NEARLY STATIONARY AND DISSIPATING SYSTEM NEAR
THE COAST BY 72 HOURS.  GIVEN THE UNCERTAINTIES IN THE FORECAST
TRACK...INTENSITY...AND WIND RADII... THE TROPICAL STORM WATCH IS
UNCHANGED FROM THIS MORNING.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      09/2100Z 30.8N  80.1W    40 KT
 12HR VT     10/0600Z 30.6N  80.6W    35 KT
 24HR VT     10/1800Z 30.2N  80.8W    35 KT
 36HR VT     11/0600Z 29.8N  80.9W    30 KT
 48HR VT     11/1800Z 29.5N  80.9W    30 KT
 72HR VT     12/1800Z 29.5N  80.9W    25 KT...DISSIPATING
 96HR VT     13/1800Z...DISSIPATED
 
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FORECASTER KNABB
 
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