








ZCZC MIATCDAT2 ALL TTAA00 KNHC DDHHMM HURRICANE EARL DISCUSSION NUMBER 34 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL072010 500 PM EDT THU SEP 02 2010 DATA FROM A RECONNAISSANCE PLANE INDICATE THAT EARL HAS WEAKENED A LITTLE BIT THIS AFTERNOON. THE CENTRAL PRESSURE ROSE TO 947 MB...AND A BLEND OF THE SFMR MEASUREMENTS AND FLIGHT-LEVEL WINDS SUGGEST THAT THE INITIAL INTENSITY HAS DECREASED TO 100 KNOTS. EARL SHOULD CONTINUE TO WEAKEN GRADUALLY AS THE SHEAR INCREASES AND THE HURRICANE SHOULD WEAKEN EVEN FASTER AFTER 24 HOURS AS IT MOVES OVER A COLDER OCEAN. AFTER CROSSING CANADA IN 48 HOURS...EARL SHOULD BECOME POST-TROPICAL/EXTRATROPICAL AND THEN DISSIPATE AS IT IS ABSORBED BY A MUCH LARGER EXTRATROPICAL CYCLONE. SATELLITE AND RECONNAISSANCE FIXES SHOW...AS ANTICIPATED...THAT EARL HAS TURNED NORTHWARD AND IS MOVING 360 DEGREES AT 16 KNOTS. THE STEERING PATTERN CONTROLLING THE MOTION OF EARL...AND THE CONSISTENCY IN TRACK GUIDANCE...HAVE BEEN ADEQUATELY DESCRIBED IN PREVIOUS DISCUSSIONS. EARL IS ABOUT TO BECOME EMBEDDED IN THE MID-LATITUDE FLOW AND IT IS READY TO GRADUALLY TURN TO THE NORTH-NORTHEAST AND NORTHEAST WITH AN INCREASE IN FORWARD SPEED. ALTHOUGH THE MAXIMUM WINDS IN THE CORE HAVE DECREASED...EARL CONTINUES TO BE A LARGE AND POWERFUL HURRICANE. FORECAST POSITIONS AND MAX WINDS INITIAL 02/2100Z 32.5N 75.2W 100 KT 12HR VT 03/0600Z 34.8N 74.8W 95 KT 24HR VT 03/1800Z 38.0N 72.7W 85 KT 36HR VT 04/0600Z 41.7N 69.0W 75 KT 48HR VT 04/1800Z 46.5N 64.5W 50 KT...POST-TROP/EXTRATROP 72HR VT 05/1800Z...DISSIPATED $$ FORECASTER AVILA NNNN






ZCZC MIATCDAT3 ALL TTAA00 KNHC DDHHMM TROPICAL STORM FIONA DISCUSSION NUMBER 13 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL082010 500 PM AST THU SEP 02 2010 THERE HAS BEEN LITTLE CHANGE WITH FIONA DURING THE DAY. THE STORM CONTINUES THE PATTERN OBSERVED DURING THE LAST DAY OR SO OF BURSTS OF CONVECTION FORMING NEAR THE CENTER...THEN SHEARING AWAY. AN ASCAT PASS FROM LATE THIS MORNING SHOWED MAXIMUM WINDS OF ABOUT 40 KT. GIVEN THE WELL-DOCUMENTED LOW BIAS OF THAT INSTRUMENT...45 KT SEEMS LIKE A REASONABLE INITIAL WIND SPEED. THE INTENSITY FORECAST IS DIFFICULT BECAUSE IT SEEMS LIKE FIONA HAS BEEN WITHSTANDING THE SHEAR BETTER THAN MOST TROPICAL CYCLONES. THE LATEST INTENSITY GUIDANCE DOES NOT WEAKEN THE STORM AS QUICKLY AS EARLIER...BUT IS ACTUALLY PRETTY CLOSE TO THE PREVIOUS FORECAST. THUS NO CHANGES ARE MADE TO THE LAST NHC FORECAST. AFTER 72 HOURS...ALL OF THE GLOBAL MODELS SHOW THE TROPICAL CYCLONE SHEARING OUT AS IT MOVES NORTHEASTWARD. FIONA HAS TURNED A LITTLE MORE AND IS NOW MOVING 335/15. THERE IS NO CHANGE IN SYNOPTIC REASONING WITH THE CYCLONE MOVING AROUND A SUBTROPICAL ANTICYCLONE. THE STORM SHOULD TURN TOWARD THE NORTH... THEN NORTHEAST AS IT STARTS TO MOVE INTO THE MID-LATITUDES. THE MODELS ARE GENERALLY SLOWER THAN THE PREVIOUS CYCLE...BUT SINCE THE CYCLONE CONTINUES SPEEDING ALONG...THE NHC FORECAST WILL STAY ON THE FASTER SIDE OF THE GUIDANCE ENVELOPE...WITH LITTLE CHANGE TO THE TRACK. THERE IS REASONABLE AGREEMENT THAT FIONA WILL BE CLOSE TO BERMUDA IN 36-48 HOURS. FORECAST POSITIONS AND MAX WINDS INITIAL 02/2100Z 25.6N 66.4W 45 KT 12HR VT 03/0600Z 27.5N 66.8W 45 KT 24HR VT 03/1800Z 29.7N 66.4W 45 KT 36HR VT 04/0600Z 31.7N 65.4W 40 KT 48HR VT 04/1800Z 33.7N 64.1W 35 KT 72HR VT 05/1800Z 38.0N 61.0W 25 KT...DISSIPATING 96HR VT 06/1800Z...DISSIPATED $$ FORECASTER BLAKE/BROWN NNNN



