[Tropical] Tropical Cyclone Discussion

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WTNT43 KNHC 180905
TCDAT3

HURRICANE GORDON DISCUSSION NUMBER  11
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL082012
500 AM AST SAT AUG 18 2012

GORDON HAS BECOME BETTER ORGANIZED DURING THE PAST FEW HOURS.
CONVECTION HAS WRAPPED ALL THE WAY AROUND THE CENTER...AND
RECENT TRMM AND SSM/I OVERPASSES SHOWED AN EYE HAS DEVELOPED.
SATELLITE INTENSITY ESTIMATES FROM TAFB AND SAB WERE 55 KT AT 0600
UTC...AND AN AMSU ESTIMATE FROM CIMSS AT 0454 UTC WAS 64 KT.  BASED
ON THESE DATA AND THE SUBSEQUENT INCREASE IN ORGANIZATION...GORDON
IS UPGRADED TO A HURRICANE.

THE INITIAL MOTION IS 090/16.  A LARGE DEEP-LAYER LOW CENTERED WEST
OF THE BRITISH ISLES SHOULD STEER GORDON EASTWARD TO EAST-
NORTHEASTWARD FOR THE NEXT 48-72 HR.  AFTER THAT...A SLOWER MOTION
TOWARD THE EAST IS EXPECTED AS THE LOW LIFTS OUT TO THE NORTHEAST
AND A LOW-LEVEL RIDGE BUILDS TO THE NORTH AND NORTHWEST OF GORDON.
THE NEW FORECAST TRACK IS SIMILAR TO THE PREVIOUS TRACK AND LIES
NEAR THE CENTER OF THE TRACK GUIDANCE ENVELOPE.

THE VERTICAL WIND SHEAR IS CURRENTLY LIGHT AND THE SEA SURFACE
TEMPERATURES ARE RELATIVELY WARM...FAVORABLE CONDITIONS FOR
STRENGTHENING OR AT LEAST MAINTAINING THE CURRENT INTENSITY FOR THE
NEXT 12-18 HR.  THE NEW INTENSITY FORECAST THUS CALLS FOR GORDON TO
REMAIN A HURRICANE TODAY.  AFTER THAT...INCREASING SHEAR...
DECREASING SSTS...AND THE ONSET OF EXTRATROPICAL TRANSITION SHOULD
CAUSE A STEADY WEAKENING.  GORDON IS FORECAST TO BECOME
EXTRATROPICAL BY 72 HR AND DISSIPATE COMPLETELY BY 120 HR IN
AGREEMENT WITH THE GLOBAL MODEL GUIDANCE.


FORECAST POSITIONS AND MAX WINDS

INIT  18/0900Z 34.0N  40.7W   65 KT  75 MPH
 12H  18/1800Z 34.0N  37.7W   65 KT  75 MPH
 24H  19/0600Z 34.5N  33.7W   60 KT  70 MPH
 36H  19/1800Z 35.3N  29.9W   55 KT  65 MPH
 48H  20/0600Z 36.5N  26.5W   50 KT  60 MPH
 72H  21/0600Z 38.5N  20.5W   35 KT  40 MPH...POST-TROP/EXTRATROP
 96H  22/0600Z 38.5N  16.5W   30 KT  35 MPH...POST-TROP/EXTRATROP
120H  23/0600Z...DISSIPATED

$$
FORECASTER BEVEN


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