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| #43778 (Received by flhurricane at: 11:05 PM 02.Sep.2005) TCDAT4 TROPICAL STORM MARIA DISCUSSION NUMBER 7 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 11 PM EDT FRI SEP 02 2005 THE CONVECTIVE PATTERN OF MARIA HAD DETERIORATED MARKEDLY DURING BETWEEN 18Z AND 00Z... WITH SUBSTANTIAL WARMING OF THE INFRARED CLOUD TOP TEMPERATURES. MICROWAVE IMAGERY FROM SSMI AT 2152Z AND FROM SSMIS AT 2324Z REVEALED VERY LITTLE DEEP CONVECTION NEAR THE CENTER AND ONLY REMAINING IN LIMITED PORTIONS OF THE WESTERN SEMICIRCLE. DVORAK INTENSITY ESTIMATES AT 00Z WERE 3.0/45 KT FROM TAFB AND SAB...BUT THE DATA T NUMBERS HAD COME DOWN TO 2.5. MORE RECENT INFRARED IMAGERY INDICATES A BURST OF CONVECTION IN THE NORTHERN SEMICIRCLE... WITHOUT WHICH IT WOULD BE TEMPTING TO ADJUST THE INITIAL INTENSITY SLIGHTLY DOWNWARD... SO THE ADVISORY INTENSITY IS KEPT AT 45 KT. IT IS A LITTLE CHALLENGING TO PRECISELY LOCATE THE CENTER OF CIRCULATION... BUT WITH THE HELP OF THE MICROWAVE OVERPASSES JUST BEFORE 00Z... THE INITIAL MOTION ESTIMATE IS 305/10... SIMILAR TO EARLIER TODAY. THE STORM IS BEING STEERED NORTHWESTWARD ALONG THE WESTERN EXTENT OF THE SUBTROPICAL RIDGE THAT IS ORIENTED EAST TO WEST ALONG ABOUT 25N. MODEL GUIDANCE IS IN GOOD AGREEMENT ON A GRADUAL TURN... BETWEEN THIS RIDGE AND A TROUGH TO THE NORTHWEST... TOWARD THE NORTH-NORTHWEST DURING THE NEXT 72 HOURS OR SO... WITH A LITTLE MORE SPREAD BEYOND THAT TIME. THE LATTER PORTIONS OF SOME OF THESE MODEL FORECASTS ARE A LITTLE COMPLICATED... WITH A VARIETY OF EVOLUTIONS. THE NOGAPS SUGGESTS A WEAKENED MARIA WILL MERGE IN ABOUT FOUR DAYS WITH A LOW PRESSURE SYSTEM NEAR BERMUDA TO FORM A STRENGTHENING EXTRATROPICAL CYCLONE ON DAY 5. THE UKMET DOES NOT FORECAST THIS EXTRATROPICAL DEVELOPMENT BUT HAS MARIA STALLING EAST OF BERMUDA BY THAT TIME... AND THERE IS NOTHING LEFT OF MARIA IN THE GFS BY 72 HOURS. THE NEW OFFICIAL FORECAST IS VERY SIMILAR TO THE PREVIOUS ADVISORY AND TO THE MODEL CONSENSUS...AS A COMPROMISE BETWEEN THE VARIOUS SOLUTIONS. THE INTENSITY FORECAST GUIDANCE IS A LITTLE CLEARER THAN LAST NIGHT. THE 18Z GFDL... AS IN THE EARLIER 12Z RUN... FORECASTS MARIA TO BECOME A HURRICANE WITHIN 36 HOURS...AND THE SHIPS GUIDANCE IS SIMILAR. ALL OF THE GLOBAL MODELS... HOWEVER... FORECAST AT LEAST GRADUAL WEAKENING OF MARIA DURING THE NEXT FEW DAYS. THE OFFICIAL INTENSITY FORECAST WILL REMAIN SIMILAR TO THE PREVIOUS ADVISORY AND FORECAST MARIA TO BECOME A HURRICANE... BUT GIVEN THE CURRENT DISORGANIZATION OF THE CONVECTION AND THE GFDL/SHIPS GUIDANCE... DELAY THE STRENGTHENING A LITTLE LONGER. FORECASTER KNABB FORECAST POSITIONS AND MAX WINDS INITIAL 03/0300Z 22.4N 51.4W 45 KT 12HR VT 03/1200Z 23.7N 52.8W 50 KT 24HR VT 04/0000Z 25.5N 54.1W 60 KT 36HR VT 04/1200Z 27.5N 55.0W 65 KT 48HR VT 05/0000Z 29.3N 55.7W 65 KT 72HR VT 06/0000Z 32.0N 56.5W 65 KT 96HR VT 07/0000Z 34.0N 57.0W 65 KT 120HR VT 08/0000Z 36.0N 56.5W 65 KT |
