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| #163371 (Received by flhurricane at: 3:34 PM 11.Dec.2007) TCDAT2 SUBTROPICAL STORM OLGA DISCUSSION NUMBER 4 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL172007 400 PM EST TUE DEC 11 2007 AN ASCAT PASS FROM LATE THIS MORNING SUGGESTS THAT THE WINDS TO THE NORTH OF THE CENTER MAY HAVE DECREASED A LITTLE...BUT A RECONNAISSANCE AIRCRAFT WILL REACH THE AREA SHORTLY...AND I WOULD PREFER TO WAIT FOR THEIR REPORTS BEFORE ADJUSTING THE ESTIMATED INTENSITY. GRAND TURK ISLAND RECENTLY REPORTED A SUSTAINED WIND OF 31 KT. THERE HAS BEEN AN INCREASE IN CONVECTION NEAR THE CENTER OVER THE PAST COUPLE OF HOURS...AND THE ASCAT DATA ALSO SUGGEST THAT THE RADIUS OF MAXIMUM WINDS MAY BE DECREASING. IF THIS IS CONFIRMED BY THE AIRCRAFT...OLGA COULD BE CLASSIFIED AS A TROPICAL CYCLONE THIS EVENING. THE CENTER OF OLGA MADE LANDFALL IN THE DOMINICAN REPUBLIC JUST TO THE SOUTH OF PUNTA CANA AROUND 18Z. THE MOTION OF THE CENTER HAS BEEN ERRATIC...BUT OVERALL IS ESTIMATED TO BE 270/11. THERE HAS BEEN LITTLE CHANGE TO THE SYNOPTIC REASONING...WHICH CALLS FOR OLGA TO BE STEERED BASICALLY WESTWARD TO THE SOUTH OF A LOW- TO MID-LEVEL RIDGE OVER THE WESTERN ATLANTIC. AFTER 48 HOURS...OLGA WILL BE ROUNDING THE PERIPHERY OF THIS RIDGE...BUT THERE IS LIKELY TO BE LITTLE LEFT OF THE CYCLONE BY THEN. THE OFFICIAL FORECAST IS VERY CLOSE TO THE GFS AND THE DYNAMICAL MODEL CONSENSUS. WATER VAPOR IMAGERY SUGGESTS THAT WESTERLY SHEAR IS BEGINNING TO INCREASE OVER THE CENTER OF CIRCULATION. GLOBAL MODELS CONTINUE TO INDICATE THAT THE UPPER LOW TO THE WEST OF THE CYCLONE WILL WEAKEN...ALLOWING THE SHEAR TO INCREASE. THIS...COUPLED WITH THE INTERACTION OF THE CENTER WITH HISPANIOLA...SHOULD RESULT IN A DECAY OF THE SYSTEM. A STRONG PRESSURE GRADIENT IS LIKELY TO PERSIST TO THE NORTH OF THE DECAYING CYCLONE...HOWEVER...AND WINDS THERE WILL BE SLOW TO DIMINISH. 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 TONIGHT...WHERE FLASH FLOODS AND MUD SLIDES ARE ALSO LIKELY. FORECAST POSITIONS AND MAX WINDS INITIAL 11/2100Z 18.5N 68.8W 40 KT...INLAND 12HR VT 12/0600Z 18.5N 71.4W 35 KT...INLAND 24HR VT 12/1800Z 18.6N 74.5W 30 KT...OVER WATER 36HR VT 13/0600Z 18.9N 77.8W 25 KT...REMNANT LOW 48HR VT 13/1800Z 19.2N 80.5W 25 KT...REMNANT LOW 72HR VT 14/1800Z 19.5N 83.0W 25 KT...REMNANT LOW 96HR VT 15/1800Z...DISSIPATED $$ FORECASTER FRANKLIN |
