TROPICAL DEPRESSION #4
ISSUED: 10:00 P.M. – WEDNESDAY – 8/15/01
TD#4 CONTINUES TO MOVE QUICKLY TOWARD THE WEST.
CURRENT MOTION IS WEST (270) AT 20 KTS.
MOST SIGNIFICANT CHANGE OVER THE LAST 6 HOURS HAS BEEN THE
MUCH IMPROVED OUTFLOW OVER THE NORTHERN SEMI-CIRCLE. LATEST IR SAT PICS AS WELL AS WV LOOPS SHOW THIS IMPROVING
OUTFLOW. LATEST IR IMAGES ALSO SHOW
INCREASE IN CONVECTION OVER THE WESTERN SEMI-CIRCLE OF THE OVERALL CIRCULATION
WITH CLOUD TOPS ON THE ORDER OF –70/-75C.
THE CENTER OF CIRCULATION HOWEVER IS TO THE EAST OF THE DEEPEST
CONVECTION. IN SHORT, T.D. #4
CONTINUES TO BECOME SLOWLY BUT STEADILY BETTER ORGANIZED.
AN UPGRADE TO TROPICAL STORM STATUS IS LIKELY WITHIN THE NEXT 1-2
ADVISORIES FROM TPC. RAPID FORWARD MOTION IS THE ONLY FACTOR I SEE
HINDERING/SLOWING DEVELOPMENT.
TRACK: ONCE
AGAIN I’M IN AGREEMENT WITH LATEST TPC TRACK PACKAGE. SYSTEM IS EMBEDDED IN DEEP EASTERLIES TO SOUTH OF STRONG
RIDGE TO THE NORTH. RIDGE IS FCST
TO BUILD WEST NEXT 24-48 HOURS AND THUS GENERAL WEST TO MORE WEST-NORTHWEST
MOTION BY 48-72 HOURS IS EXPECTED. A
GRADUAL REDUCTION IN FORWARD SPEED IS EXPECTED BEYOND 18-24 HOURS. UNTIL THEN A BRISK 20 MPH+ PACE IS EXPECTED.
LATEST CIMSS LOWER LEVEL WIND ANALYSIS SUPPORTS A SLOWING OF FORWARD
SPEED STARTING IN THE NEXT 18-24 HOURS. ONCE
SYSTEM BECOMES MORE VERTICALLY STACKED IT WILL BE GUIDED MORE BY THE UPPER LEVEL
WINDS. CYCLONE SHOULD ENTER INTO THE CARIBBEAN SOMEWHERE BETWEEN
13-15 NORTH DURING FRIDAY MORNING OR EARLY AFTERNOON.
INTENSITY: TOUGH CALL HERE. FOR SEVERAL RUNS IN A ROW SHIPS HAS PERSISTED IN A 90-100 KT.
HURRICANE BY 72 HOURS. LATEST GFDL
HAS NOW FOLLOWED SUIT AND IS NO LONGER DISSIPATING THE SYSTEM.
WATER TEMPS ARE INCREASINGLY WARMER AHEAD OF THE DEPRESSION….UPPER
LEVEL WINDS ARE FAVORABLE AND ARE FORECAST TO REMAIN THAT WAY.
WILL GO ALONG WITH LATEST TPC FCST OF 70 KTS. BY 72 HOURS.
STILL BELIEVE THE ONLY THING HINDERING MORE RAPID DEVELOPMENT IS FAST
FORWARD SPEED. ONCE THE FORWARD
SPEED SLOWS INTENSIFICATION SHOULD FOLLOW RATHER QUICKLY.
INTENSITY FORECASTING IS A VERY DIFFICULT AND IS NOT AN
EXACT SCIENCE BY ANY MEANS. RESIDENTS
OF THE ISLANDS ESPECIALLY THE CENTRAL AND NORTHERN ISLANDS SHOULD BE AWARE OF
THIS AND REALIZE THEY MAY HAVE TO DEAL WITH A HURRICANE DURING THE NEXT 36-48
HOURS. WATCHES WILL LIKELY BE
ISSUED LATER TONIGHT.
LONGER RANGE TRACK: LATEST
NCEP MANUAL PROGS TRACKS THE SYSTEM OVER THE DOMINICAN REPUBLIC BY MONDAY…THEN
TOWARD THE S.E. BAHAMA ISLANDS…THEN TO VCTY 35N/72 WEST BY NEXT WEDNESDAY.
I BELIEVE THIS IS NOT THE RIGHT IDEA.
ALTHOUGH THERE WILL BE A WEAKNESS DEVELOPING NEAR THE WESTERN EXTENSION
OF THE SUB-TROPICAL RIDGE I DO NOT BELIEVE IT WILL BE NEARLY ENOUGH TO DRAW THE
SYSTEM NORTH ACROSS THE DOMINICAN REPUBLIC.
OVER TIME A MORE NW TRACK IS LIKELY AND I BELIEVE THE SYSTEM IS DESTINED
FOR THE GULF OF MEXICO EITHER BY WAY OF NORTH OR SOUTH OF CUBA.
THIS IMPLIES SYSTEM TILL TANGLE WITH THE CUBAN LAND MASS…EITHER THE
EASTERN END OR THE WESTERN END. IN
SHORT…AT THIS TIME I DO NOT SEE THIS AS A RECURVING STORM OVER THE WESTERN
ATLANTIC….NOR DO I SEE IT AS A THREAT TO THE EASTERN UNITED STATES WITH THE
SOLE EXCEPTION OF THE SOUTHERN ONE HALF OF FLORIDA…AT THIS EARLY VANTAGE POINT
THERE IS SOME THREAT THERE. THAT IS
DAYS AWAY SO THE WORD FOR NOW IS MONITOR AND FOLLOW FUTURE UPDATES.