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| #39406 (Received by flhurricane at: 10:37 PM 13.Aug.2005) TCDAT4 TROPICAL STORM IRENE DISCUSSION NUMBER 38 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 11 PM EDT SAT AUG 13 2005 IRENE HAS BECOME A LITTLE BETTER ORGANIZED DURING THE PAST 6 HOURS WITH A STRONG BURST OF DEEP CONVECTION HAVING DEVELOPED OVER AND SOUTH OF THE WELL-DEFINED LOW-LEVEL CENTER. A 13/2232Z SSMI OVERPASS DEPICTED A LARGE BUT CLOSED EYE FEATURE IN THE LOW-LEVELS ...BUT THE MID- AND UPPER-LEVEL CIRCULATIONS WERE STILL OPEN TO THE NORTH. THE LAST RECON FLIGHT-LEVEL WIND DATA SUPPORTED 55-60 KT... SO WITH THE INCREASE IN DEEP CONVECTION SINCE THAT TIME...AN INTENSITY OF AT LEAST 60 KT SEEMS... ALTHOUGH IT COULD BE STRONGER. IF THE CURRENT CONVECTIVE TREND CONTINUES...THEN THE NEXT RECON FLIGHT AT 06Z SHOULD FIND IRENE AS A HURRICANE. THE INITIAL MOTION ESTIMATE IS 335/09. THERE IS NO SIGNIFICANT CHANGE TO THE PREVIOUS FORECAST TRACK OR REASONING THROUGH 96 HOURS. IRENE APPEARS TO BE MOVING THROUGH A WEAKNESS IN THE BERMUDA RIDGE AND IT SHOULD GRADUALLY TURN NORTHWARD ON SUNDAY AND THEN TURN NORTHEASTWARD AND ACCELERATE BY MONDAY AS THE CYCLONE GETS CAUGHT UP IN THE STRONG MID-TROPOSPHERIC WESTERLIES THAT LIE ACROSS THE NORTHERN U.S. AND NORTH ATLANTIC. BY 96 HOURS...A DEEP-LAYER MID-LATITUDE LOW PRESSURE SYSTEM IS EXPECTED TO RAPIDLY ACCELERATE THE THEN EXTRATROPICAL IRENE NORTHEASTWARD INTO THE FAR NORTH ATLANTIC. THE OFFICIAL TRACK IS SIMILAR TO THE NHC MODEL CONSENSUS AND IS CLOSE TO THE PREVIOUS FORECAST THROUGH 96 HOURS...AND THEN FASTER AND TO THE LEFT AFTER THAT. GIVEN THE IMPRESSIVE LOW-LEVEL EYE FEATURE NOTED IN THE SSMI IMAGERY AND THE RECENT INCREASE IN DEEP CONVECTION...IRENE COULD BECOME A LITTLE STRONGER THAN WHAT IS INDICATED BY THE OFFICIAL FORECAST ONCE THE CYCLONE MOVES ONTO AND NORTH OF THE BERMUDA RIDGE AXIS WHERE THE STEERING FLOWS SHOULD BECOME MORE ALIGNED AND REDUCE THE SHEAR. THE OFFICIAL INTENSITY FORECAST IS SIMILAR TO THE PREVIOUS PACKAGE AND REMAINS ABOVE THE SHIPS AND GFDL INTENSITY MODELS. FORECASTER STEWART FORECAST POSITIONS AND MAX WINDS INITIAL 14/0300Z 32.0N 69.9W 60 KT 12HR VT 14/1200Z 33.5N 70.0W 65 KT 24HR VT 15/0000Z 35.6N 69.3W 65 KT 36HR VT 15/1200Z 37.4N 67.3W 65 KT 48HR VT 16/0000Z 38.7N 64.3W 60 KT 72HR VT 17/0000Z 41.0N 58.0W 55 KT...BECOMING EXTRATROPICAL 96HR VT 18/0000Z 45.0N 50.0W 45 KT...EXTRATROPICAL 120HR VT 19/0000Z 55.0N 38.0W 40 KT...EXTRATROPICAL |
