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| #54265 (Received by flhurricane at: 10:49 AM 27.Oct.2005) TCDAT1 TROPICAL STORM BETA DISCUSSION NUMBER 3 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 11 AM EDT THU OCT 27 2005 MORNING SATELLITE IMAGERY SHOWS BETA AS A SMALL BUT WELL ORGANIZED TROPICAL STORM. VISIBLE IMAGERY SHOWS A CENTRAL DENSE OVERCAST WITH SOME OUTER BANDING IN BOTH THE EAST AND WEST QUADRANTS...WITH INFRARED IMAGERY INDICATING CLOUD TOPS TO -80C. A RECENT SSM/I OVERPASS SHOWS AN SMALL EYEWALL FORMING UNDER THE CDO. SATELLITE INTENSITY ESTIMATES ARE 45 KT FROM TAFB AND SAB...AND THAT IS THE INITIAL INTENSITY. THE CENTER OF BETA IS SOMEWHAT TO THE EAST OF THE PREVIOUS ADVISORY...AND THE INITIAL MOTION IS A SOMEWHAT UNCERTAIN 350/2. BETA IS DRIFTING TOWARD A WEAKNESS IN THE SUBTROPICAL RIDGE CAUSED BY A LARGE DEEP-LAYER TROUGH OVER THE EASTERN UNITED STATES. LARGE-SCALE MODELS SUGGESTS THAT AFTER A SERIES OF SHORTWAVES PASS THROUGH THE SOUTHERN END OF THE TROUGH IN THE NEXT 24-36 HR...THE TROUGH SHOULD LIFT A LITTLE NORTHWARD AND ALLOW WEAK RIDGING TO BUILD ACROSS THE NORTHWESTERN CARIBBEAN. THIS EVOLUTION SHOULD CAUSE BETA TO DRIFT SLOWLY NORTHWARD OR NORTH-NORTHWESTWARD FOR THE NEXT 24-36 HR...FOLLOWED BY A WESTWARD MOTION. ALL THE DYNAMICAL MODELS EXCEPT THE CANADIAN...WHICH HAS HAD A NORTHWARD BIAS IN SIMILAR SITUATIONS...FOLLOW THIS SCENARIO. THE NEW FORECAST TRACK IS SHIFTED TO THE NORTH AND EAST OF THE PREVIOUS TRACK BASED ON THE INITIAL POSITION AND MOTION. THE FORECAST TRACK NOW CALLS FOR LANDFALL IN NORTHEASTERN NICARAGUA IN 72 TO 96 HR. WITH THE SMALL EYEWALL AND GOOD OUTFLOW IN THE WESTERN SEMICIRCLE... BETA APPEARS SET UP FOR RAPID INTENSIFICATION. INDEED...THE RAPID INTENSIFICATION INDEX ATTACHED TO THE SHIPS MODEL SHOWS A 56 PERCENT CHANCE OF 25 KT OR GREATER STRENGTHENING DURING THE NEXT 24 HOURS. THE NEW INTENSITY FORECAST WILL NOT INCREASE QUITE THAT MUCH...BUT DOES SHOW SIGNIFICANT STRENGTHENING DURING THE NEXT 72 HR SIMILAR TO THAT OF THE GFDL. THE INTENSITY FORECAST MAY NEED TO BE REVISED SIGNIFICANTLY UPWARD IN THE NEXT ADVISORY IF CURRENT TRENDS CONTINUE. ONE POSSIBLE RESTRAINING FACTOR IS THAT THE WARM WATER OF THE SOUTHWESTERN CARIBBEAN IS RELATIVELY SHALLOW...AND THE SLOW MOTION OF BETA WILL LIKELY RESULT IN SOME UPWELLING OF COLD WATER. HOWEVER...THE EFFECTS OF THIS MAY NOT BE FELT FOR 24 HR OR MORE. FORECASTER BEVEN FORECAST POSITIONS AND MAX WINDS INITIAL 27/1500Z 11.5N 81.3W 45 KT 12HR VT 28/0000Z 11.9N 81.3W 55 KT 24HR VT 28/1200Z 12.4N 81.4W 65 KT 36HR VT 29/0000Z 12.9N 81.7W 75 KT 48HR VT 29/1200Z 13.3N 82.1W 80 KT 72HR VT 30/1200Z 13.5N 83.0W 85 KT 96HR VT 31/1200Z 13.5N 84.5W 40 KT...INLAND 120HR VT 01/1200Z 13.0N 86.5W 25 KT...DISSIPATING |
