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TROPICAL DEPRESSION FIVE DISCUSSION NUMBER   1
NATIONAL WEATHER SERVICE MIAMI FL
5 PM EDT SUN SEP 01 2002
 
AIR FORCE RESERVE RECONNAISSANCE AIRCRAFT...ALONG WITH SURFACE... 
RADAR...AND SATELLITE OBSERVATIONS INDICATE THAT THE TROPICAL 
DISTURBANCE EAST OF THE CENTRAL FLORIDA COAST HAS DEVELOPED INTO 
TROPICAL DEPRESSION FIVE. RECON FOUND 850 MB WINDS OF 35 KT AT 
AROUND 1900Z AND THE MELBOURNE DOPPLER RADAR HAS OCCASIONALLY BEEN 
INDICATING 36 TO 40 KT WINDS BETWEEN 10000 AND 13000 FT. RECON ALSO 
FOUND A RATHER BROAD LOW-LEVEL CIRCULATION AND A SURFACE PRESSURE OF 
ONLY 1014 MB. BASED ON THIS INFORMATION...THE INITIAL INTENSITY IS 
SET TO 30 KT. OUTFLOW IS GOOD TO THE EAST BUT SLIGHTLY RESTRICTED TO 
THE WEST DUE TO WEAK UPPER-LEVEL WESTERLY SHEAR.

THE INITIAL MOTION ESTIMATE IS 285/06. THERE IS SIGNIFICANT 
DIVERGENCE AMONG THE VARIOUS NHC MODELS WITH THE PATTERN BEING MORE 
REPRESENTATIVE OF A SQUASHED SPIDER. THE SHALLOW AND MEDIUM BAM 
MODELS AND THE LBAR MODEL TAKE THE DEPRESSION INLAND NEAR ST. 
AUGUSTINE FLORIDA IN ABOUT 36 HOURS...WHILE THE REMAINDER OF THE 
MODELS ARE SPREAD ALL ABOUT THE COMPASS. 01/12Z UPPER-AIR DATA 
INDICATES THE SURFACE TO 700 MB SUBTROPICAL RIDGE NORTH OF THE 
DEPRESSION EXTENDS WESTWARD TO THE TENNESSEE VALLEY...WHILE A BREAK 
IN THE RIDGE EXISTS FROM 500 MB ON UP. THE GLOBAL MODELS GRADUALLY 
ERODE THE LOW-LEVEL RIDGE AND TAKE THE SMALL DEPRESSION SLOWLY 
NORTHWARD AFTER 24 HOURS AND THEN TURN IT TO THE NORTHEAST AS A DEEP 
MID-LATITUDE TROUGH AND COLD FRONT PUSH SOUTHEAST TO NEAR THE U.S. 
EAST COAST BY 72 HOURS. GIVEN THE LARGE SPREAD IN THE MODEL GUIDANCE
...I HAVE DECIDED TO KEEP THE FORWARD SPEED SLOW AND MOVE THE 
CYCLONE NORTHWEST AND THEN NORTHWARD SIMILAR TO THE AVN MODEL...BUT 
FARTHER WEST THAN THE GFDL MODEL. HOWEVER...SINCE STEERING CURRENTS 
ARE WEAK...SOME ERRATIC MOTION IS POSSIBLE. THIS TRACK UNCERTAINTY 
HAS ALSO PROMPTED THE ISSUANCE OF A TROPICAL STORM WATCH FOR THE 
COASTAL AREAS OF NORTHEAST FLORIDA AND SOUTHEAST GEORGIA.

GIVEN THE INCREASING WEST TO NORTHWESTERLY SHEAR EXPECTED AFTER 24 
HOURS...ONLY MODEST INTENSIFICATION IS EXPECTED. THE SHIPS INTENSITY 
MODEL BRINGS THE SYSTEM TO TROPICAL STORM STRENGTH BY 24 HOURS AND 
59 KT BY 72 HOURS. HOWEVER...THE OFFICIAL INTENSITY FORECAST WAS 
HELD LOWER THAN SHIPS GIVEN THAT THE MID- TO UPPER-LEVEL SHEAR IS 
EXPECTED TO BE 20 TO 25 KT WITH PROBABLE DRY AIR INTRUSION AFTER 24 
HOURS.
 
FORECASTER STEWART
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     01/2100Z 29.0N  79.2W    30 KTS
12HR VT     02/0600Z 29.3N  80.0W    35 KTS
24HR VT     02/1800Z 30.0N  80.6W    40 KTS
36HR VT     03/0600Z 30.6N  80.7W    45 KTS
48HR VT     03/1800Z 31.7N  80.6W    45 KTS
72HR VT     04/1800Z 32.5N  79.5W    40 KTS
 
 
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