Tropical Storm GREG
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TROPICAL STORM GREG DISCUSSION NUMBER 4
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
8 PM PDT THU AUG 11 2005
A BURST OF DEEP CONVECTION BEGAN AT ABOUT 22Z NEAR THE ESTIMATED LOW
LEVEL CENTER LOCATION... AND THIS CONVECTION HAS PERSISTED THIS
EVENING. EXCEPT FOR A LITTLE RESTRICTION TO THE NORTHEAST... UPPER
LEVEL OUTFLOW HAS BECOME WELL ESTABLISHED. DVORAK INTENSITY
ESTIMATES ARE NOW 3.0 FROM BOTH TAFB AND SAB... SO THE INTENSITY IS
INCREASED TO 45 KT. CONDITIONS APPEAR FAVORABLE FOR FURTHER
INTENSIFICATION... AS VERTICAL SHEAR IS EXPECTED TO WEAKEN EVEN
MORE... AND ALONG THE FORECAST TRACK GREG SHOULD REMAIN OVER SSTS
EXCEEDING 27 CELSIUS. THE OFFICIAL INTENSITY FORECAST IS IN
BETWEEN THE GFDL AND SHIPS SOLUTIONS.
GREG HAS TURNED TOWARD THE WEST... 280/8... OBVIOUSLY UNAFFECTED BY
HURRICANE FERNANDA WHICH IS TOO FAR WEST TO INDUCE GREG TOWARD THE
NORTH. INSTEAD... GREG IS BEING STEERED BY A LOW TO MID LEVEL
RIDGE TO ITS NORTH. THE ONLY DYNAMICAL MODELS THAT SEEM TO HAVE A
REASONABLE HANDLE ON THE INITIAL MOTION ARE THE GFDL AND GFS... SO
THESE MODELS ARE GIVEN FAR GREATER WEIGHT THAN THE OTHERS IN THE
TRACK FORECAST. EVEN THE GFDL AND GFS FORECAST A TRACK
CONSIDERABLY SLOWER AND SOUTH OF THE PREVIOUS FORECAST... IN
RESPONSE TO A WEAKENING OF THE RIDGE TO THE NORTH JUST OFF THE
COAST OF MEXICO. THE NEW OFFICIAL TRACK FORECAST LEANS TOWARD
THESE MODELS BUT IS KEPT NORTH OF THEM FOR THE SAKE OF CONTINUITY.
FORECASTER KNABB
FORECAST POSITIONS AND MAX WINDS
INITIAL 12/0300Z 13.6N 111.9W 45 KT
12HR VT 12/1200Z 13.8N 112.9W 55 KT
24HR VT 13/0000Z 14.0N 114.1W 65 KT
36HR VT 13/1200Z 14.2N 115.0W 70 KT
48HR VT 14/0000Z 14.4N 115.9W 70 KT
72HR VT 15/0000Z 14.5N 117.5W 65 KT
96HR VT 16/0000Z 14.5N 120.0W 65 KT
120HR VT 17/0000Z 15.0N 123.5W 65 KT
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