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Tropical Depression ANA (Text)

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TROPICAL DEPRESSION ANA DISCUSSION NUMBER  20
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL022009
1100 PM AST SUN AUG 16 2009
 
RADAR IMAGERY FROM GUADELOUPE SUGGESTS THAT THE LOW-LEVEL CENTER OF
ANA HAS TURNED TOWARD THE WEST-NORTHWEST AND IS MOVING QUICKLY AT
AN INITIAL MOTION OF 285/23.  ALTHOUGH SOME DEEP CONVECTION HAS
RECENTLY RE-DEVELOPED...IT IS ORIENTED LINEARLY ALONG A NORTH-SOUTH
AXIS AND APPEARS MORE REPRESENTATIVE OF A TROPICAL WAVE. THE CENTER
APPEARS REASONABLY WELL-DEFINED ON THE GUADELOUPE RADAR BUT THIS IS
LIKELY DEPICTING A MID-LEVEL CIRCULATION RATHER THAN ONE AT THE
SURFACE.  AT THIS TIME WE WOULD RATHER NOT STOP ADVISORIES WHILE
THE SYSTEM IS MOVING ACROSS THE LESSER ANTILLES.  HOWEVER IF
SURFACE OBSERVATIONS FROM THOSE ISLANDS CONFIRM THE LACK OF A
CENTER...ADVISORIES WILL BE TERMINATED EARLY MONDAY.
 
VERY FEW OF THE DYNAMICAL MODELS SHOW ANY RE-STRENGTHENING...AND A
FEW SUCH AS THE GFS...HWRF...AND GFDL LOSE THE VORTEX AFTER ABOUT
36 HOURS.  THE TRACK GUIDANCE INDICATES THAT ANA SHOULD BE MOVING
OVER THE HIGH TERRAIN OF HISPANIOLA IN 24-36 HOURS...AND IT IS
DOUBTFUL THAT ITS CIRCULATION WILL MAKE IT ACROSS THAT ISLAND
INTACT.  THE OFFICIAL FORECAST SHOWS ANA BECOMING A REMNANT LOW BY
36 HOURS AFTER IT BEGINS CROSSING LAND...BUT IT IS POSSIBLE THAT IT
COULD BECOME AN OPEN WAVE AT ANY TIME.  THE TRACK FORECAST IS
SHIFTED NORTH OF THE PREVIOUS FORECAST TOWARD THE SHALLOW LAYER BAM
TRACK AND IN LINE WITH THE GFS AND ECMWF SINCE IT IS ASSUMED THAT
THE REMNANT CIRCULATION WILL BE STEERED BY THE LOW-LEVEL FLOW.
 
TROPICAL STORM WATCHES WILL REMAIN IN EFFECT UNTIL IT IS CLEAR THAT
ANA WILL NOT RE-STRENGTHEN OR UNTIL IT PASSES THE LEEWARD ISLANDS
LATER TONIGHT.

FORECAST POSITIONS AND MAX WINDS
 
INITIAL      17/0300Z 16.0N  61.2W    30 KT
 12HR VT     17/1200Z 16.7N  64.4W    30 KT
 24HR VT     18/0000Z 18.1N  68.6W    30 KT
 36HR VT     18/1200Z 19.6N  72.6W    25 KT...REMNANT LOW
 48HR VT     19/0000Z 21.2N  76.0W    25 KT...REMNANT LOW
 72HR VT     20/0000Z 24.0N  81.0W    25 KT...REMNANT LOW
 96HR VT     21/0000Z 26.0N  84.0W    25 KT...REMNANT LOW
120HR VT     22/0000Z 28.0N  86.0W    25 KT...REMNANT LOW
 
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FORECASTER BERG
 
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