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| #163322 (Received by flhurricane at: 9:52 AM 11.Dec.2007) TCDAT2 SUBTROPICAL STORM OLGA DISCUSSION NUMBER 3 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL172007 1000 AM EST TUE DEC 11 2007 RECENT BUOY...QUIKSCAT...AND SHIP REPORTS INDICATE THAT OLGA'S PEAK WINDS ARE NEAR 40 KT...AND EXTEND FARTHER AWAY FROM THE CENTER THAN EARLIER ESTIMATED. THE STRUCTURE OF OLGA...WITH ITS STRONGEST WINDS LOCATED STILL 100-200 NMI FROM CENTER...CONTINUES TO BE CONSISTENT WITH THAT OF A SUBTROPICAL CYCLONE. THE INITIAL MOTION ESTIMATE IS 260/13...ALTHOUGH THE CENTER HAS MOVED LITTLE OVER THE PAST FEW HOURS. A LOW- TO MID-LEVEL RIDGE OVER THE WESTERN ATLANTIC IS EXPECTED TO KEEP OLGA ON A BASIC WESTWARD PATH NEAR THE SOUTH COAST OF HISPANIOLA AND INTO THE NORTHWESTERN CARIBBEAN SEA...AND MODEL GUIDANCE IS IN RELATIVELY GOOD AGREEMENT ON THIS SCENARIO. THE OFFICIAL FORECAST LIES ALONG THE SOUTHERN EDGE OF THE GUIDANCE ENVELOPE AND IS IN BEST AGREEMENT WITH THE GFS. ALTHOUGH THE CIRCULATION OF OLGA WILL BE INTERACTING WITH THE RUGGED TERRAIN OF HISPANIOLA...THE PRESSURE GRADIENT AWAY FROM THE CENTER...WHERE THE STRONGEST WINDS ARE LOCATED...WILL BE SLOW TO DIMINISH. THE UPPER-LEVEL TROUGH CURRENTLY OVER THE CYCLONE IS FORECAST BY ALL THE GLOBAL MODELS TO WEAKEN AND BE REPLACED BY STRONG NORTHWESTERLY SHEAR OVER THE NEXT 24-36 HOURS OR SO...AND WHEN THIS HAPPENS OLGA SHOULD DEGENERATE TO A REMNANT LOW. THE PRIMARY THREAT FROM OLGA IS HEAVY RAINFALL...WHICH IS ALREADY PRODUCING LIFE-THREATENING MUD SLIDES IN PUERTO RICO. THESE RAINS WILL BE SPREADING ACROSS HISPANIOLA OVER THE NEXT 24 HOURS...WHERE FLASH FLOODS AND MUD SLIDES ARE ALSO LIKELY. FORECAST POSITIONS AND MAX WINDS INITIAL 11/1500Z 18.1N 68.0W 40 KT 12HR VT 12/0000Z 18.0N 70.5W 35 KT 24HR VT 12/1200Z 18.1N 74.0W 30 KT 36HR VT 13/0000Z 18.2N 77.4W 30 KT...REMNANT LOW 48HR VT 13/1200Z 18.2N 80.5W 25 KT...REMNANT LOW 72HR VT 14/1200Z 18.0N 85.0W 25 KT...REMNANT LOW 96HR VT 15/1200Z...DISSIPATED $$ FORECASTER FRANKLIN |
