September 25, 2009
Tropical Depression 8 forms in the Atlantic
TD 8 has formed but at the moment the forecast has it meandering harmlessly in the open Atlantic. We'll keep an eye on it and send out more alerts if the situation changes.
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.
