|
Show Selection: |
| #289901 (Received by flhurricane at: 10:49 AM 21.Aug.2009) TCDAT3 HURRICANE BILL DISCUSSION NUMBER 25 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL032009 1100 AM AST FRI AUG 21 2009 AFTER SOME DETERIORATION OF THE CLOUD PATTERN EARLY THIS MORNING...VISIBLE SATELLITE IMAGES INDICATE THAT THE EYE HAS BECOME APPARENT AGAIN ALTHOUGH IS NOT AS DISTINCT IT WAS YESTERDAY. MICROWAVE IMAGES SHOW A CONVECTIVE RING ASSOCIATED WITH THE EYEWALL WITH AN OUTER CONVECTIVE BAND. AT THIS POINT IT IS DIFFICULT TO KNOW WHETHER THIS IS THE BEGINNING OF THE FORMATION OF A SECONDARY EYEWALL. IT IS ALSO POSSIBLE THAT THE WEAKENING OVERNIGHT WAS RELATED TO AN EYEWALL REPLACEMENT CYCLE. THE AVERAGE OF THE LATEST OBJECTIVE AND SUBJECTIVE DVORAK T-NUMBERS INDICATE THAT INITIAL INTENSITY CAN BE ADJUSTED DOWN TO 100 KT. AN AIR FORCE HURRICANE HUNTER PLANE WILL CHECK THE INTENSITY LATER TODAY. THE HURRICANE STILL HAS TO MOVE OVER THE WARMEST OCEAN YET TODAY AND SATURDAY...AND THE SHEAR IS LOW AS DIAGNOSED BY THE SHIPS MODEL. BILL HAS THE POTENTIAL TO RESTRENGTHEN A LITTLE BUT MOST LIKELY THE HURRICANE WILL EXPERIENCE SOME FLUCTUATIONS IN INTENSITY DURING THE NEXT 24 HOURS. THEREAFTER...SHEAR AND A COLDER OCEAN SHOULD WORK AGAINST INTENSIFICATION AND BILL SHOULD BEGIN ITS EXTRATROPICAL TRANSITION BEYOND 72 HOURS. BILL IS MOVING TOWARD THE NORTHWEST OR 325 DEGREES AT 16 KNOTS WHILE EMBEDDED IN VERY WELL-ESTABLISHED STEERING CURRENTS ASSOCIATED WITH THE AZORES-BERMUDA HIGH. BILL IS ALREADY REACHING THE SOUTHWESTERN EDGE OF THE RIDGE AND SOON WILL BECOME STEERED NORTHWARD AND NORTHEASTWARD BY THE FLOW BETWEEN THE HIGH AND A LARGE MID-LATITUDE TROUGH DEVELOPING OVER THE EASTERN UNITED STATES. THESE TWO FEATURES ARE BEING HANDLED CONSISTENTLY ACROSS MOST OF THE DYNAMICAL MODELS AND CONSEQUENTLY THE TRACK GUIDANCE IS TIGHTLY PACKED. THE FACT THAT TRACK GUIDANCE IS IN VERY GOOD AGREEMENT INCREASES MY CONFIDENCE IN THE TRACK FORECAST. LARGE SWELLS GENERATED BY THIS HURRICANE WILL AFFECT A LARGE PORTION OF THE WESTERN NORTH ATLANTIC COASTAL AREA DURING THE NEXT FEW DAYS. THESE SWELLS WILL LIKELY CAUSE EXTREMELY DANGEROUS SURF AND LIFE-THREATENING RIP CURRENTS. PLEASE CONSULT STATEMENTS ISSUED BY YOUR LOCAL WEATHER OFFICE AND METEOROLOGICAL SERVICES FOR MORE DETAILS. FORECAST POSITIONS AND MAX WINDS INITIAL 21/1500Z 27.6N 66.3W 100 KT 12HR VT 22/0000Z 29.8N 67.7W 100 KT 24HR VT 22/1200Z 33.0N 68.5W 100 KT 36HR VT 23/0000Z 36.5N 68.4W 90 KT 48HR VT 23/1200Z 41.0N 66.0W 80 KT 72HR VT 24/1200Z 48.5N 52.0W 60 KT 96HR VT 25/1200Z 53.5N 27.5W 50 KT...EXTRATROPICAL 120HR VT 26/1200Z 57.5N 10.0W 40 KT...EXTRATROPICAL $$ FORECASTER AVILA |
