433
WTNT43 KNHC 252034
TCDAT3
TROPICAL DEPRESSION EIGHT DISCUSSION NUMBER 1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL082009
500 PM AST FRI SEP 25 2009
SATELLITE IMAGERY INDICATES THAT THE TROPICAL WAVE OVER THE EASTERN
ATLANTIC HAS DEVELOPED SUFFICIENT CONVECTION AND CIRCULATION TO BE
DESIGNATED A TROPICAL DEPRESSION. SATELLITE INTENSITY ESTIMATES
BASED ON BANDING IN THE NORTHERN SEMICIRCLE ARE 30 KT FROM TAFB AND
25 KT FROM SAB. THE INITIAL INTENSITY IS SET TO 30 KT. THE CIRRUS
OUTFLOW IS FAIR TO GOOD IN THE NORTHERN SEMICIRCLE AND RESTRICTED
ELSEWHERE.
THE DEPRESSION IS CURRENTLY EXPERIENCING 10-15 KT OF SOUTHWESTERLY
VERTICAL WIND SHEAR. THE SHEAR IS FORECAST TO INCREASE AFTER 12 HR
OR SO...WITH THE FORECAST TRACK LIKELY TAKING THE CYCLONE NEAR AN
UPPER-LEVEL TROUGH BY 48 HR. THIS...COMBINED WITH A TONGUE OF
COOLER SEA SURFACE TEMPERATURES ALONG THE FORECAST TRACK...SUGGEST
THAT THE SYSTEM WILL ONLY HAVE A SMALL CHANCE TO STRENGTHEN BEFORE
ENCOUNTERING CONDITIONS THAT SHOULD CAUSE DISSIPATION. THE
INTENSITY FORECAST CALLS FOR SLIGHT STRENGTHENING DURING THE FIRST
12 HR...FOLLOWED BY GRADUAL WEAKENING. THE SYSTEM IS FORECAST TO
BECOME A REMNANT LOW BY 72 HR AND DISSIPATE COMPLETELY BY 96 HR.
THE INITIAL MOTION IS 305/12. THE CYCLONE IS FORECAST TO CONTINUE
THIS GENERAL MOTION TOWARD AN UPPER-LEVEL TROUGH AND AN ASSOCIATED
WEAKNESS IN THE LOW/MID-LEVEL SUBTROPICAL RIDGE FOR THE NEXT 36 HR
OR SO...THEN TURN NORTHWARD INTO THE WEAKNESS BEFORE DISSIPATION.
FORECAST POSITIONS AND MAX WINDS
INITIAL 25/2100Z 16.4N 31.6W 30 KT
12HR VT 26/0600Z 17.3N 33.1W 35 KT
24HR VT 26/1800Z 18.4N 35.0W 35 KT
36HR VT 27/0600Z 19.8N 36.8W 30 KT
48HR VT 27/1800Z 21.4N 38.1W 25 KT
72HR VT 28/1800Z 24.0N 39.5W 20 KT...REMNANT LOW
96HR VT 29/1800Z...DISSIPATED
FORECASTER BEVEN
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