[Tropical] Tropical Cyclone Discussion

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WTNT44 KNHC 101458
TCDAT4

TROPICAL STORM MARIA DISCUSSION NUMBER  16
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL142011
1100 AM AST SAT SEP 10 2011

MARIA HAS BECOME SIGNIFICANTLY LESS ORGANIZED DURING THE LAST
12-18 HOURS.  THE LARGE UPPER-LEVEL LOW AND TROUGH LOCATED NORTH
OF PUERTO RICO IS PRODUCING MODERATE WEST TO NORTHWESTERLY SHEAR
OVER THE CYCLONE.  SATELLITE IMAGERY...SURFACE OBSERVATIONS...AND
DATA FROM AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT INDICATE
THAT THE WEAK CIRCULATION CENTER IS APPROACHING ANTIGUA.  THE
CIRCULATION IS NOT VERY WELL DEFINED...BUT HAS ENOUGH DEFINITION TO
MAINTAIN ADVISORIES FOR NOW.  THE INITIAL INTENSITY IS GENEROUSLY
KEPT AT 35 KT...WITH THE ASSUMPTION THAT TROPICAL-STORM-FORCE WINDS
ARE OCCURRING IN THE CONVECTION WELL TO THE NORTHEAST OF THE
CENTER.  BECAUSE THESE WINDS ARE SO FAR REMOVED FROM THE
CENTER...AND NOT EXPECTED TO IMPACT THE LESSER ANTILLES...ALL
TROPICAL STORM WARNINGS HAVE BEEN DISCONTINUED.

MODEL GUIDANCE SUGGESTS THAT SHEAR WILL CONTINUE OVER THE CYCLONE
DURING THE NEXT COUPLE OF DAYS.  THE NEW INTENSITY FORECAST
THEREFORE CALLS FOR CONTINUED WEAKENING DURING THE NEXT DAY OR
TWO.  IF MARIA SURVIVES AS A TROPICAL CYCLONE...THE UPPER-LEVEL
ENVIRONMENT COULD BECOME A LITTLE MORE FAVORABLE WHEN IT IS
FORECAST TO BE EAST OF THE BAHAMAS.  THE OFFICIAL FORECAST REFLECTS
RESTRENGTHENING...BUT GIVEN THE CURRENT LACK OF STRUCTURE OF THE
CYCLONE...IS MUCH LOWER THAN THE OBJECTIVE GUIDANCE.

THE TRACK GUIDANCE IS IN GOOD AGREEMENT ON A NORTHWESTWARD
MOTION DURING THE NEXT COUPLE OF DAYS AROUND THE WESTERN SIDE OF THE
SUBTROPICAL RIDGE.  A TROUGH MOVING ACROSS THE SOUTHEASTERN UNITED
STATES IN 2-3 DAYS IS FORECAST TO TURN MARIA NORTHWARD...THEN
NORTH-NORTHEASTWARD LATER IN THE FORECAST PERIOD.  THE NEW TRACK
FORECAST IS A LITTLE TO THE RIGHT OF THE PREVIOUS ADVISORY DURING
THE FIRST COUPLE OF DAYS...BUT THE REMAINDER OF THE TRACK IS
ESSENTIALLY AN UPDATE OF THE PREVIOUS NHC FORECAST.


FORECAST POSITIONS AND MAX WINDS

INIT  10/1500Z 17.3N  61.5W   35 KT  40 MPH
 12H  11/0000Z 18.4N  63.2W   30 KT  35 MPH
 24H  11/1200Z 19.9N  64.9W   30 KT  35 MPH
 36H  12/0000Z 21.4N  66.5W   30 KT  35 MPH
 48H  12/1200Z 22.7N  68.0W   35 KT  40 MPH
 72H  13/1200Z 24.9N  70.2W   45 KT  50 MPH
 96H  14/1200Z 29.0N  71.0W   55 KT  65 MPH
120H  15/1200Z 36.0N  68.0W   55 KT  65 MPH

$$
FORECASTER BROWN/FRANKLIN


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