[Tropical] Tropical Cyclone Discussion

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WTNT42 KNHC 150847
TCDAT2

TROPICAL STORM GERT DISCUSSION NUMBER   6
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL072011
500 AM AST MON AUG 15 2011

GERT HAS STRENGTHENED OVERNIGHT.  AN 0543 UTC AMSR-E PASS AND
DOPPLER RADAR DATA FROM BERMUDA INDICATE THAT GERT HAS A FAIRLY
WELL-DEVELOPED INNER CORE AND A SPIRAL BAND THAT WRAPS ABOUT
THREE-QUARTERS OF THE WAY AROUND THE CENTER.  IN ADDITION...
SATELLITE IMAGES INDICATE THAT BANDING FEATURES HAVE BECOME MORE
ESTABLISHED DURING THE PAST SEVERAL HOURS.  THE INITIAL WIND SPEED
IS INCREASED TO 50 KT...WHICH IS SLIGHTLY HIGHER THAN THE DVORAK
CLASSIFICATIONS FROM TAFB AND SAB.  THERE IS STILL SOME NORTHERLY
SHEAR IMPACTING THE CYCLONE...AS SEEN IN THE UW-CIMSS SATELLITE
ANALYSIS AND THE SOUTHWARD TILT WITH HEIGHT OF THE CIRCULATION
CENTER IN THE AMSR-E IMAGERY.  AN AIR FORCE RESERVE RECONNAISSANCE
AIRCRAFT WILL BE INVESTIGATING GERT LATER THIS MORNING AND WILL
PROVIDE A BETTER ASSESSMENT OF ITS INTENSITY.

THE TROPICAL STORM APPEARS TO HAVE TURNED TO THE NORTH DURING THE
PAST 6 HOURS...AND THE LATEST INITIAL MOTION ESTIMATE IS 355/12.
GERT IS FORECAST TO TURN NORTH-NORTHEASTWARD AND THEN NORTHEASTWARD
AND GAIN FORWARD SPEED DURING THE NEXT FEW DAYS AS IT BECOMES
EMBEDDED IN THE STRONGER FLOW TO THE EAST OF A DEEP-LAYER TROUGH
MOVING OFFSHORE OF THE UNITED STATES EAST COAST.  THE OFFICIAL
FORECAST IS ESSENTIALLY AN UPDATE OF THE PREVIOUS ONE AND IS NEAR
THE MULTI-MODEL CONSENSUS.

SOME ADDITIONAL INTENSIFICATION OF GERT APPEARS LIKELY DURING THE
NEXT 24 HOURS AS IT REMAINS OVER RELATIVELY WARM WATER AND BENEATH
AN UPPER-LEVEL ANTICYCLONE.  AFTER 24 HOURS...GERT IS FORECAST TO
MOVE OVER WATERS COOLER THAN 26C...WHICH SHOULD INDUCE SOME
WEAKENING.  IN 2 TO 3 DAYS THE STORM IS FORECAST TO MOVE INTO AN
ENVIRONMENT OF STRONG SOUTHWESTERLY SHEAR AND WATERS COOLER THAN
20C...WHICH SHOULD RESULT IN EXTRATROPICAL TRANSITION DURING THAT
TIME PERIOD.  THE GLOBAL MODELS ARE IN AGREEMENT THAT A FRONT WILL
ABSORB GERT IN 3 TO 4 DAYS.

INTERESTS IN BERMUDA ARE REMINDED NOT TO FOCUS ON THE EXACT FORECAST
TRACK OF GERT...AS ONLY A SLIGHT DEVIATION TO THE LEFT DURING THE
NEXT 6 TO 12 HOURS COULD BRING STRONG WINDS CLOSE TO...OR OVER...THE
ISLAND.

FORECAST POSITIONS AND MAX WINDS

INIT  15/0900Z 31.3N  63.4W   50 KT  60 MPH
 12H  15/1800Z 33.5N  62.9W   55 KT  65 MPH
 24H  16/0600Z 36.8N  60.8W   60 KT  70 MPH
 36H  16/1800Z 40.3N  57.2W   55 KT  65 MPH
 48H  17/0600Z 43.0N  51.5W   50 KT  60 MPH
 72H  18/0600Z 48.0N  36.5W   40 KT  45 MPH...POST-TROP/EXTRATROP
 96H  19/0600Z...DISSIPATED

$$
FORECASTER CANGIALOSI/BRENNAN

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