[Tropical] Tropical Cyclone Discussion

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WTNT44 KNHC 071457
TCDAT4

TROPICAL STORM MARIA DISCUSSION NUMBER   4
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL142011
1100 AM AST WED SEP 07 2011

CONSIDERING THAT THERE WERE TROPICAL STORM FORCE WINDS IN AN EARLIER
ASCAT PASS AND A RECENT ONE WITH STRONGER WINDS...THE DEPRESSION HAS
BEEN UPGRADED TO TROPICAL STORM MARIA WITH AN INITIAL INTENSITY OF
45 KNOTS. THE CONVECTION IS NOT VERY DEEP AT THIS TIME AND THE ONLY
IMPRESSIVE FEATURE OF THE OVERALL CLOUD PATTERN IS A CURVED BAND TO
THE NORTH OF THE CENTER. THE OUTFLOW IS WELL ESTABLISHED IN THE
WESTERN SEMICIRCLE. GLOBAL MODELS SUGGEST THAT THE UPPER-LEVEL
WINDS WILL BE ONLY MARGINALLY FAVORABLE FOR STRENGTHENING DUE TO
THE PRESENCE OF SOUTHEASTERLY SHEAR. IN FACT...NEITHER SHIPS NOR
LGEM DEVELOPS THE CYCLONE TOO MUCH. THE MOST AGGRESSIVE MODEL IS
THE GFDL AND IT ONLY INTENSIFIES THE CYCLONE NEAR THE END OF THE
FORECAST PERIOD. GIVEN SUCH GUIDANCE...THE OFFICIAL FORECAST CALLS
FOR A SLIGHT STRENGTHENING ONLY.

MARIA IS RACING TOWARD THE WEST OR 280 DEGREES AT 20 KNOTS. MOST OF
THE TRACK MODELS...WHICH ARE IN EXCELLENT AGREEMENT...KEEP MARIA ON
THIS GENERAL HEADING WITH THE SAME SPEED FOR THE NEXT 2 TO 3 DAYS.
ONCE MARIA REACHES THE EXTREME NORTHEASTERN CARIBBEAN SEA IN ABOUT 3
DAYS...THE STEERING CURRENTS WEAKEN A LITTLE BIT AND THE CYCLONE
SHOULD DECREASE IN FORWARD SPEED. A TURN TO THE WEST-NORTHWEST
AROUND THE WESTERN EDGE OF THE SUBTROPICAL RIDGE SHOULD THEN BEGIN.
THE OFFICIAL FORECAST LIES IN THE MIDDLE OF THE GUIDANCE ENVELOPE
WHICH IS BOUNDED BY THE GFS ON THE NORTH AND THE ECMWF ON THE
SOUTH.


FORECAST POSITIONS AND MAX WINDS

INIT  07/1500Z 13.0N  42.0W   45 KT  50 MPH
 12H  08/0000Z 13.5N  45.0W   45 KT  50 MPH
 24H  08/1200Z 14.0N  49.0W   45 KT  50 MPH
 36H  09/0000Z 14.5N  53.0W   50 KT  60 MPH
 48H  09/1200Z 15.5N  56.5W   55 KT  65 MPH
 72H  10/1200Z 17.5N  62.0W   55 KT  65 MPH
 96H  11/1200Z 20.0N  66.0W   55 KT  65 MPH
120H  12/1200Z 23.0N  70.0W   55 KT  65 MPH

$$
FORECASTER AVILA


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