15Z Tropical Update

TROPICAL DEPRESSION FOUR FORECAST #1
TROPICAL FORECAST CENTER
11:33 AM EDT MONDAY AUGUST 2, 2010

AT 11AM EDT/1500Z...THE CENTER OF NEWLY DEVELOPED TROPICAL DEPRESSION 4 WAS LOCATED NEAR 12.6N 41.1W OR ABOUT 1365 MILES EAST OF THE LESSER ANTILLES. THE DEPRESSION WAS MOVING TO THE WEST-NORTHWEST AT 17 MPH AND THIS MOTION AND A FASTER RATE OF SPEED IS EXPECTED OVER THE NEXT 24 HOURS. MAXIMUM SUSTAINED WINDS ARE NEAR 35 MPH AND THIS DEPRESSION IS EXPECTED TO BECOME A TROPICAL STORM BY TONIGHT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1006MB/29.71IN.

I HAVE BEEN WATCHING THIS SYSTEM FOR SEVERAL DAYS NOW AND WAS CLOSE TO BECOMING A TROPICAL DEPRESSION DURING THE PAST 24 HOURS. THIS MORNING...A CLOSED CIRCULATION WAS DETECTED IN MICROWAVE SATELLITE IMAGERY AND THOUGH THUNDERSTORMS HAVE DECREASED SOME...FORECASTS WILL BEGIN ON TD 4. INITIAL INTENSITY IS SET AT 30 KTS AND THIS IS THE SAME THAT THE DVORAK ESTIMATES SHOW ALSO. THIS DEPRESSION IS IN A FAVORABLE ENVIRONMENT TO CONTINUE TO STRENGTHEN OVER THE NEXT FEW DAYS AND WILL LIKELY BE A TROPICAL STORM WITHIN THE NEXT 12 HOURS...AND CLOSE TO HURRICANE STRENGTH IN ABOUT 72 HOURS...STRONGER THAN NHCs INTENSITY FORECAST. AFTER ABOUT 72 HOURS THE DEPRESSION WILL BE INTERACTING WITH AN UPPER LEVEL LOW AND DRIER AIR NORTH OF PUERTO RICO AND THIS COULD BRING AN END TO THE STRENGTHENING OF THIS SYSTEM...IN FACT I HAVE PUT A DECREASE IN WINDS BETWEEN DAYS 4 AND 5. THIS REMAINS TO BE SEEN.

INITIAL MOTION IS 290/15 KTS. THE DEPRESSION IS BEING STEERED BY A FAIRLY STRONG SUB-TROPICAL RIDGE TO THE NORTH OF THE DEPRESSION. A GENERAL WEST-NORTHWEST MOTION AND PERHAPS AT A FASTER MOTION IS EXPECTED THROUGH ABOUT 72 HOURS. FORECAST MODELS DO INDICATED A WEAKNESS AND THIS WEAKNESS COULD SLOW DOWN THE SYSTEM BY DAYS 4 AND 5. FORECAST MODELS DURING THIS TIME ARE FAIRLY SPREAD OUT WITH A FEW OF THE MODELS RECURVING THE DEPRESSION OUT TO SEA. MY FORECAST TRACK IS IN THE MIDDLE OF THE GUIDANCE AND SLOWER THAN MOST OF THE MODELS AND NHCs FORECAST TRACK DUE TO POSSIBLE SLOWING OF THE SYSTEM AND THE UNCERTAINITY OF THE FORECAST TRACK BEYOND DAY 4.

FORECAST POSITION AND INTENSITY:

02/15Z 12.6N 41.1W 30 KTS
03/03Z 13.5N 43.5W 35 KTS
03/15Z 14.8N 47.0W 45 KTS
04/03Z 16.3N 50.5W 50 KTS
04/15Z 17.7N 54.0W 55 KTS
05/15Z 20.5N 59.5W 60 KTS
06/15Z 23.0N 62.5W 60 KTS
07/15Z 24.0N 65.5W 55 KTS

JACKSON