Show Selection: |
#533213 (Received by flhurricane at: 10:56 AM 10.Aug.2012) TCDAT2 TROPICAL DEPRESSION SEVEN DISCUSSION NUMBER 4 NWS NATIONAL HURRICANE CENTER MIAMI FL AL072012 1100 AM AST FRI AUG 10 2012 THE CONVECTIVE STRUCTURE OF THE DEPRESSION HAS CHANGED LITTLE OVER THE PAST FEW HOURS...AND DVORAK CI NUMBERS ARE STILL 1.5 FROM TAFB AND SAB. WITHOUT ANY ADDITIONAL DATA AVAILABLE TO US AT THIS TIME...WE ARE KEEPING THE CYCLONE AS A 30-KT DEPRESSION. THE CENTER OF THE DEPRESSION HAS BECOME MORE APPARENT IN VISIBLE IMAGERY...AND THE UPDATED POSITION YIELDS A FASTER 12-HR MOTION OF 270/20 KT. THE SUBTROPICAL RIDGE TO THE NORTH OF THE DEPRESSION IS EXPECTED TO CONTINUE STEERING THE CYCLONE WESTWARD INTO THE CARIBBEAN SEA OVER THE NEXT FEW DAYS. THE RIDGE SHOULD BREAK DOWN OVER THE FAR WESTERN ATLANTIC AND GULF OF MEXICO BY DAYS 4 AND 5...BUT SINCE THE CYCLONE IS EXPECTED TO REMAIN WEAK...NOT MUCH GAIN IN LATITUDE IS EXPECTED. THE NEW NHC FORECAST IS AN UPDATE OF THE PREVIOUS ONE TO ACCOUNT FOR THE FASTER INITIAL MOTION AND CONTINUES TO LIE CLOSE TO THE GFS SOLUTION. NEEDLESS TO SAY...THE INTENSITY FORECAST IS A DIFFICULT ONE. THE ONLY ENVIRONMENTAL PARAMETER THAT APPEARS IDEAL FOR STRENGTHENING IS THE SEA SURFACE TEMPERATURE. ON THE OTHER HAND...THE DEPRESSION IS LIKELY BEING AFFECTED BY SURROUNDING DRY AIR...WHICH COULD BE COMPOUNDED BY INCREASING SOUTHERLY TO SOUTHWESTERLY SHEAR OVER THE NEXT COUPLE OF DAYS. THE FAST MOTION OF THE DEPRESSION WOULD NORMALLY FAVOR LESS STRENGTHENING AS WELL. PROBABLY DUE TO THESE FACTORS...THE MAJORITY OF THE GLOBAL MODELS CONTINUE TO DEGENERATE THE CYCLONE INTO AN OPEN WAVE OVER THE EASTERN CARIBBEAN SEA. AS PLAUSIBLE AS THAT SCENARIO IS...THE OFFICIAL FORECAST STILL KEEPS THE SYSTEM AS A TROPICAL CYCLONE THROUGH THE 5-DAY PERIOD BUT AT A SLIGHTLY LOWER INTENSITY. GIVEN THE HIGH UNCERTAINTY IN THE INTENSITY FORECAST...AND THE POSSIBILITY THAT THE DEPRESSION COULD BECOME AN OPEN WAVE EARLIER THAN INDICATED BY THE GLOBAL MODELS...TROPICAL STORM WATCHES AND WARNINGS ARE NOT BEING ISSUED FOR PORTIONS OF THE LESSER ANTILLES AT THIS TIME. FORECAST POSITIONS AND MAX WINDS INIT 10/1500Z 13.7N 49.5W 30 KT 35 MPH 12H 11/0000Z 13.7N 52.2W 35 KT 40 MPH 24H 11/1200Z 13.8N 55.7W 40 KT 45 MPH 36H 12/0000Z 14.1N 59.1W 40 KT 45 MPH 48H 12/1200Z 14.6N 62.5W 40 KT 45 MPH 72H 13/1200Z 15.5N 69.0W 40 KT 45 MPH 96H 14/1200Z 16.0N 76.0W 40 KT 45 MPH 120H 15/1200Z 17.0N 83.5W 40 KT 45 MPH $$ FORECASTER BERG |