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TROPICAL DEPRESSION TWO DISCUSSION NUMBER 2
NATIONAL WEATHER SERVICE MIAMI FL
5 AM EDT THU JUL 12 2001
TROPICAL DEPRESSION TWO HAS REMAINED STEADY THROUGH MOST OF THIS
MORNING WITH SOME SLIGHT IMPROVEMENT IN THE OUTER BANDING FEATURES
...WHILE THE INNER CONVECTION HAS WEAKENED. THE INITIAL INTENSITY IS
MAINTAINED AT 25 KT BASED ON A SATELLITE INTENSITY ESTIMATE OF
T1.5...25 KT...FROM BOTH TAFB AND AFWA. OUTFLOW IS GOOD TO THE
NORTH AND FAIR ELSEWHERE.
THE INITIAL MOTION IS 295/16. OVERNIGHT...THE DEPRESSION HAS
ACCELERATED MORE TOWARD THE WEST. HOWEVER...THE INITIAL POSITION
WAS KEPT A LITTLE FARTHER NORTH THAN THE SATELLITE POSITIONS IN
ORDER TO MAINTAIN CONTINUITY WITH THE PREVIOUS FORECAST AND THE BUOY
POSITION FROM ABOUT 6 HOURS AGO. BUT EVEN WITH THIS...THE INITIAL
POSITION AND OFFICIAL FORECAST TRACK IS SOUTH OF AND FASTER THAN THE
PREVIOUS FORECAST. ALTHOUGH THE MODEL GUIDANCE IS SPLIT INTO TWO
CAMPS... THERE IS STILL REASONABLE AGREEMENT AMONG THE VARIOUS
FORECAST TRACKS. THE CLIMATOLOGICAL MODELS TAKE THE DEPRESSION
WEST-NORTHWEST... WHEREAS THE DYNAMICAL AND STATISTICAL-DYNAMICAL
MODELS TAKE THE SYSTEM MORE WESTWARD. THE 00Z AVN AND NOGAPS MODELS
DID NOT INITIALIZE THE DEPRESSION VERY WELL AND LOSE THE SYSTEM
AFTER ABOUT 24 HOURS. THE UKMET MODEL WEAKENS THE DEPRESSION SLOWLY
AND TAKES IT ALMOST DUE WEST. HOWEVER...ALL OF THE GLOBAL MODELS
AGREE ON THE SUBTROPICAL RIDGE TO THE NORTH OF THE DEPRESSION TO
GRADUALLY BUILD WESTWARD AS THE LARGE COLD LOW NORTH OF PUERTO RICO
GRADUALLY FILLS AND LIFTS OUT TO THE NORTH. THE OFFICIAL FORECAST
IS A BLEND BETWEEN THE BAM DEEP AND CLIPER MODELS.
TROPICAL DEPRESSION TWO IS CURRENTLY OVER MARGINAL SSTS FOR ANY
FURTHER DEVELOPMENT TO OCCUR. LOW-LEVEL INFLOW FROM THE NORTHEAST IS
PASSING OVER A TONGUE OF COOLER SSTS...WHILE THE WARM MOIST INFLOW
FROM THE SOUTH IS LIKELY HELPING THE RECENT REDEVELOPMENT OF
CONVECTION. ONCE THE SYSTEM MOVES WEST OF 50W LONGITUDE...SSTS
BECOME MORE FAVORABLE FOR STRENGTHENING AND THIS IS INDICATED IN THE
OFFICIAL FORECAST. THE ONE FLY-IN-THE-OINTMENT IS THE EXACT TRACK OF
THE DEPRESSION. RECENT TRENDS IN THE SATELLITE MOTIONS SUGGEST THAT
THE CYCLONE MAY BE TRACKING MORE WESTWARD. IF THE DEPRESSION TRACKS
FARTHER SOUTH THAN FORECAST...THEN THE VERTICAL SHEAR WILL BE LESS
AND MORE STRENGTHENING COULD OCCUR THAN IS CURRENTLY FORECAST.
FORECASTER STEWART
FORECAST POSITIONS AND MAX WINDS
INITIAL 12/0900Z 12.3N 46.2W 25 KTS
12HR VT 12/1800Z 13.2N 48.4W 30 KTS
24HR VT 13/0600Z 14.3N 51.1W 35 KTS
36HR VT 13/1800Z 15.2N 53.6W 40 KTS
48HR VT 14/0600Z 16.0N 56.0W 50 KTS
72HR VT 15/0600Z 17.5N 60.5W 55 KTS
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