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| #54439 (Received by flhurricane at: 10:55 AM 28.Oct.2005) TCDAT1 TROPICAL STORM BETA DISCUSSION NUMBER 7 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 11 AM EDT FRI OCT 28 2005 BETA IS GENERATING STRONG CENTRAL CONVECTION WITH TOPS TO -86C. HOWEVER...OVERPASSES FROM AMSR-E AT 0705Z AND SSM/I AT 1148Z SUGGEST THE STORM HAS BECOME SOMEWHAT SHEARED...WITH THE CONVECTION DISPLACED SOUTH AND SOUTHWEST OF THE CENTER. THERE ARE HINTS OF THIS IN VISIBLE IMAGERY AS WELL. WHILE CIRRUS EAST OF BETA ARE BLOWING TOWARD THE CENTER...ANALYSES FROM CIMSS AT THE UNIVERSITY OF WISCONSIN SHOW ONLY ABOUT 10 KT OF SHEAR...WHICH IF CORRECT DOES NOT FULLY EXPLAIN THE APPARENT STRUCTURE. SATELLITE INTENSITY ESTIMATES ARE 65 KT FROM TAFB...55 KT FROM SAB...AND 45 KT FROM AFWA. THE INITIAL INTENSITY REMAINS 55 KT BASED ON A BLEND OF THESE AND A 50 KT REPORT AT 0900Z FROM SHIPS ZCAM4 JUST SOUTH OF THE CENTER. AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT WILL INVESTIGATE BETA THIS AFTERNOON. THE INITIAL MOTION IS 360/4. BETA IS MOVING NORTHWARD TOWARD A WEAKNESS IN THE SUBTROPICAL RIDGE CAUSED BY A DEEP-LAYER TROUGH OVER THE EASTERN UNITED STATES. RAWINSONDE DATA AND WATER VAPOR IMAGERY INDICATE THAT A STRONG SHORTWAVE TROUGH IS MOVING EASTWARD ACROSS THE SOUTHEASTERN U. S. AND THE EASTERN GULF OF MEXICO. THE DYNAMICAL MODELS FORECAST HEIGHTS TO RISE IN THESE AREAS AFTER THE TROUGH MOVES INTO THE ATLANTIC IN 12-24 HR. SATELLITE IMAGERY AND SURFACE OBSERVATIONS ALSO SUGGEST THAT THE LOW-LEVEL RIDGE OVER THE WESTERN ATLANTIC AND NORTHERN CARIBBEAN IS BUILDING WESTWARD. THIS EVOLUTION SHOULD TURN BETA MORE NORTHWESTWARD DURING THE NEXT 24 HR AND MORE WESTWARD THEREAFTER. THE GFS...GFDL...NOGAPS...AND ECMWF ALL CALL FOR A VERY SHARP TURN...WHILE THE UKMET AND CANADIAN CALL FOR A MORE GRADUAL TURN. THE NEW FORECAST TRACK IS SHIFTED A LITTLE MORE TO THE NORTH BASED ON THE CURRENT POSITION AND MOTION...CALLING FOR LANDFALL IN NORTHEASTERN NICARAGUA IN 36-48 HR. THE NEW TRACK IS SOUTH OF THE UKMET BUT NORTH OF THE OVERALL MODEL CONSENSUS. IF BETA IS AS SHEARED AS THE MICROWAVE DATA SUGGESTS...THEN THE SHORT-TERM INTENSIFICATION COULD BE SLOWER THAN CURRENTLY FORECAST. THAT BEING SAID...THE SHIPS MODEL FORECASTS THE SHEAR TO DECREASE IN 12-18 HR...AND THE GFDL IS CALLING FOR BETA TO REACH 95 KT BEFORE LANDFALL. THUS...THE INTENSITY FORECAST WILL CONTINUE TO CALL FOR BETA TO REACH CATEGORY TWO INTENSITY BEFORE LANDFALL. THE CYCLONE SHOULD WEAKEN AFTER LANDFALL...AND IT COULD DISSIPATE FASTER THAN FORECAST OVER THE MOUNTAINS OF CENTRAL AMERICA. ONE OUTER RAINBAND IS CURRENTLY SPREADING ONSHORE IN NORTHEASTERN NICARAGUA AND EASTERN HONDURAS. AS BETA GETS CLOSER TO THE CENTRAL AMERICAN COAST...THE THREAT OF HEAVY RAINS...FLOODS...AND MUDSLIDES WILL INCREASE. FORECASTER BEVEN FORECAST POSITIONS AND MAX WINDS INITIAL 28/1500Z 12.9N 81.2W 55 KT 12HR VT 29/0000Z 13.3N 81.2W 65 KT 24HR VT 29/1200Z 13.9N 81.8W 75 KT 36HR VT 30/0000Z 14.2N 82.6W 85 KT 48HR VT 30/1200Z 14.6N 83.6W 80 KT...INLAND 72HR VT 31/1200Z 15.0N 85.5W 30 KT...INLAND 96HR VT 01/1200Z 15.0N 87.0W 25 KT...INLAND DISSIPATING 120HR VT 02/1200Z 15.5N 88.5W 20 KT...INLAND REMNANT LOW |
