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TROPICAL DEPRESSION ELEVEN DISCUSSION NUMBER   2
NATIONAL WEATHER SERVICE MIAMI FL
11 PM EDT TUE SEP 17 2002
 
INFRARED SATELLITE IMAGERY INDICATES TROPICAL DEPRESSION ELEVEN HAS 
CHANGED LITTLE DURING THE PAST 12 HOURS. WHILE DEEP CONVECTION HAS 
BECOME SHEARED INTO THE EASTERN SEMICIRCLE...A 17/2206Z QUIKSCAT 
OVERPASS ISTILL NDICATED A WELL-DEFINED 180 NMI CIRCULAR WIND FIELD 
ASSOCIATED WITH THE CYCLONE. THE INITIAL INTENSITY OF 30 KT IS BASED 
ON A DVORAK SATELLITE INTENSITY ESTIMATE OF T2.0...OR 30 KT...FROM 
TAFB AND A FEW 30 KT NON-RAIN CONTAMINATED QUIKSCAT WIND VECTORS.
 
THE INITIAL MOTION ESTIMATE IS 030/08. THE DEPRESSION IS BEING 
STEERED NORTH-NORTHEASTWARD BY A HIGH-LATITUDE RIDGE LOCATED TO THE 
SOUTHEAST.  HOWEVER...AS A STRONG MID-LATITUDE TROUGH STEADILY 
APPROACHES FROM THE WEST...THE CYCLONE IS EXPECTED TO GRADUALLY 
ACCELERATE MORE TOWARD THE NORTHEAST BEFORE EVENTUALLY MERGING WITH 
A COLD FRONT BY ABOUT 48 HOURS. THERE IS GOOD AGREEMENT AMONG ALL OF 
THE GLOBAL MODELS ON THIS SCENARIO. THE OFFICIAL TRACK IS TO THE 
RIGHT OF THE PREVIOUS TRACK THROUGH 36 HOURS AND THEN BACK ON TRACK 
AT 48 HOURS...AND IS ALSO VERY CLOSE TO THE AVN SOLUTION.

THERE APPEARS TO BE A BRIEF WINDOW OF OPPORTUNITY FOR A SOME SLIGHT 
INTENSIFICATION TO OCCUR DURING THE NEXT 12 HOURS OR SO AS SOME 
UPPER-LEVEL RIDGING AHEAD OF THE APPROACHING TROUGH BUILDS OVER THE 
DEPRESSION. THE AVN IS FORECASTING THE SHEAR TO BRIEFLY DROP BELOW 
10 KT IN 12 HOURS...AND THEN INCREASE ABOVE 20 KT FROM THE SOUTHWEST 
AFTER THAT. THERE WAS ONE 35 KT NON-RAIN CONTAMINATED QUIKSCAT WIND 
VECTOR NOTED...SO THE DEPRESSION IS ALREADY VERY CLOSE TO TROPICAL 
STORM STRENGTH. HOWEVER...ANY TROPICAL STORM FORCE WINDS WOULD BE 
CONFINED TO A VERY SMALL AREA IN THE SOUTHEAST QUADRANT. HOWEVER... 
THE OVERALL INTENSITY TREND OF THE SHIPS INTENSITY MODEL APPEARS TO 
BE TOO ROBUST BY BRINGING THE SYSTEM UP TO NEAR 60 KT IN 60 HOURS 
OVER 19C SST WATER. ALSO...NONE OF THE GLOBAL MODELS ARE SUGGESTING 
ANY STRONG DEEPENING DUE TO BAROCLINIC EFFECTS ONCE MERGER OCCURS.

NOTE...12 FT SEAS RADII WERE ADDED TO THE FORECAST/ADVISORY PRODUCT 
BASED ON THE QUIKSCAT WIND DATA AND WIND-WAVE FORECAST PRODUCTS.
 
FORECASTER STEWART
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     18/0300Z 34.1N  52.2W    30 KTS
12HR VT     18/1200Z 35.2N  51.1W    35 KTS
24HR VT     19/0000Z 37.2N  48.2W    30 KTS
36HR VT     19/1200Z 40.1N  44.3W    30 KTS...BECOMING EXTRATROPICAL
48HR VT     20/0000Z 44.2N  39.2W    30 KTS...EXTRATROPICAL
72HR VT     21/0000Z...ABSORBED BY LARGER EXTRATROPICAL LOW
 
 
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