[Tropical] Tropical Cyclone Discussion

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WTNT44 KNHC 131438
TCDAT4

TROPICAL STORM MARIA DISCUSSION NUMBER  28
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL142011
1100 AM AST TUE SEP 13 2011

THE STRUCTURE OF MARIA HAS NOT CHANGED MUCH THIS MORNING. THE
LOW-LEVEL CENTER IS STILL EXPOSED TO THE WEST-NORTHWEST OF THE DEEP
CONVECTION DUE TO ABOUT 20 KT OF SHEAR AS SHOWN IN THE SHIPS MODEL
AND UW-CIMSS SATELLITE ANALYSES. THE INITIAL INTENSITY IS HELD AT
45 KT IN AGREEMENT WITH THE 12Z DVORAK ESTIMATES FROM TAFB AND SAB.
THE UPPER-LEVEL LOW NORTH OF MARIA CAUSING THE SHEAR IS FORECAST TO
WEAKEN AND LIFT NORTHWARD WITHIN 24 HOURS. HOWEVER...THE UPPER-
LEVEL WINDS NEVER BECOME IDEAL FOR INTENSIFICATION ACCORDING TO THE
GLOBAL MODELS...WITH STRONG SOUTHWESTERLY FLOW DEVELOPING OVER
MARIA AHEAD OF THE LARGE MID/UPPER-LEVEL TROUGH MOVING OFF THE EAST
COAST OF THE UNITED STATES. THE STATISTICAL GUIDANCE SUGGESTS SOME
MODEST STRENGTHENING OVER THE NEXT COUPLE OF DAYS...AND THE
OFFICIAL FORECAST IS CLOSE TO A BLEND OF THE SHIPS AND THE LGEM
MODELS. MARIA SHOULD BE EXTRATROPICAL BY 72 HOURS...AND THE GLOBAL
MODELS SHOW THE CYCLONE BEING ABSORBED BY A LARGER EXTRATROPICAL
LOW BY 96 HOURS.

THE INITIAL MOTION ESTIMATE IS 335/05. MARIA WILL ACCELERATE
NORTHWARD AHEAD OF THE TROUGH MOVING OFF THE U.S. EAST COAST OVER
THE NEXT COUPLE OF DAYS AND SHOULD TURN A LITTLE EAST OF DUE NORTH
BY 48 HOURS. A FASTER NORTHEASTWARD MOTION IS EXPECTED BY 72 HOURS
AS MARIA IS ABSORBED INTO THE MID-LATITUDE WESTERLIES. THE GUIDANCE
REMAINS IN GOOD AGREEMENT ON THIS SCENARIO AND THE OFFICIAL
FORECAST IS LARGELY AN UPDATE OF THE PREVIOUS ONE...LYING TO THE
RIGHT OF THE MULTI-MODEL CONSENSUS BUT BETWEEN THE RELIABLE ECMWF
AND GFS MODELS.


FORECAST POSITIONS AND MAX WINDS

INIT  13/1500Z 22.1N  68.0W   45 KT  50 MPH
 12H  14/0000Z 23.6N  68.4W   45 KT  50 MPH
 24H  14/1200Z 26.1N  68.8W   50 KT  60 MPH
 36H  15/0000Z 29.2N  68.5W   55 KT  65 MPH
 48H  15/1200Z 33.2N  67.0W   55 KT  65 MPH
 72H  16/1200Z 43.0N  57.0W   50 KT  60 MPH...POST-TROP/EXTRATROP
 96H  17/1200Z...ABSORBED

$$
FORECASTER BRENNAN


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