ZCZC MIATCDAT1 ALL TTAA00 KNHC DDHHMM TROPICAL STORM ARLENE DISCUSSION NUMBER 3 NWS NATIONAL HURRICANE CENTER MIAMI FL AL012011 400 AM CDT WED JUN 29 2011 THUNDERSTORM COVERAGE HAS INCREASED MARKEDLY NEAR AND TO THE SOUTHEAST OF THE CENTER OF ARLENE DURING THE PAST SEVERAL HOURS. HOWEVER...A TRMM MICROWAVE PASS AT 0502 UTC DID NOT SHOW MUCH IN THE WAY OF ORGANIZATION NEAR THE CENTER...WITH A LACK OF PROMINENT BANDING. SATELLITE INTENSITY ESTIMATES SUPPORT AN INTENSITY OF ABOUT 35 KT...SO THAT WILL REMAIN THE INITIAL WIND SPEED. AN AIR FORCE RESERVE RECONNAISSANCE AIRCRAFT IS SCHEDULED TO INVESTIGATE ARLENE LATER THIS MORNING TO PROVIDE MORE INFORMATION ON THE STRUCTURE AND INTENSITY OF THE CYCLONE. UPPER-LEVEL CLOUD MOTIONS SUGGEST THAT THE SHEAR IS DECREASING...AND GIVEN AN INCREASINGLY FAVORABLE ENVIRONMENT...IT SEEMS LIKE IT IS ONLY A MATTER OF TIME BEFORE ARLENE STRENGTHENS. THE BULK OF THE INTENSITY GUIDANCE SHOWS THE SYSTEM AS A MODERATE TROPICAL STORM BEFORE LANDFALL...THOUGH THE HWRF HAS THE SYSTEM BRIEFLY AS A HURRICANE. GIVEN THE LARGE SIZE OF ARLENE AND THE LACK OF ANY INNER CORE FEATURES...HURRICANE STRENGTH APPEARS UNLIKELY...AND THE NHC FORECAST WILL STAY CLOSE TO THE INTENSITY MODEL CONSENSUS AND THE PREVIOUS FORECAST. OVERNIGHT MICROWAVE IMAGERY HAS NOT PROVIDED A DEFINITIVE CENTER POSITION...HOWEVER GEOSTATIONARY IMAGERY SUGGESTS THAT ARLENE IS STILL MOVING TOWARD THE WEST-NORTHWEST AT ABOUT 7 KT...OR EVEN A BIT FASTER THAN THAT DURING THE PAST FEW HOURS. A WESTWARD TURN IS EXPECTED LATER TODAY AS ARLENE IS STEERED AROUND A STRONG RIDGE OVER THE SOUTH-CENTRAL UNITED STATES. THE CYCLONE COULD EVEN MOVE A LITTLE SOUTH OF WEST TOMORROW DUE TO THE POSITIONING OF THE RIDGE...AS SUGGESTED BY A FEW GLOBAL MODELS. THE NEW FORECAST IS BASICALLY AN UPDATE OF THE PREVIOUS ONE...SHOWING LANDFALL IN A LITTLE OVER 24 HOURS. GIVEN THE LARGE SIZE OF THE CIRCULATION OF ARLENE...ONE SHOULD NOT FOCUS ON THE EXACT FORECAST TRACK...AS IMPACTS WILL LIKELY BE FELT OVER A LARGE PORTION OF NORTHEASTERN MEXICO WELL AWAY FROM THE CENTER. FORECAST POSITIONS AND MAX WINDS INIT 29/0900Z 21.8N 95.0W 35 KT 40 MPH 12H 29/1800Z 22.1N 95.9W 40 KT 45 MPH 24H 30/0600Z 22.1N 97.1W 50 KT 60 MPH 36H 30/1800Z 22.0N 98.2W 40 KT 45 MPH...INLAND 48H 01/0600Z 21.8N 99.4W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 02/0600Z...DISSIPATED $$ FORECASTER BLAKE/BRENNAN NNNN
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Page last modified: Tuesday, 17-Jul-2012 13:43:43 UTC