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| #513430 (Received by flhurricane at: 10:44 PM 25.May.2012) TCDAT2 SUBTROPICAL STORM BERYL DISCUSSION NUMBER 1 NWS NATIONAL HURRICANE CENTER MIAMI FL AL022012 1100 PM EDT FRI MAY 25 2012 CONVENTIONAL AND MICROWAVE SATELLITE PICTURES AS WELL AS REPORTS FROM NOAA BUOY 41002 THIS EVENING INDICATE THAT THE BROAD LOW PRESSURE AREA OFF OF THE SOUTHEASTERN UNITED STATES COAST HAS COALESCED INTO A TIGHT...WELL-DEFINED CIRCULATION. AROUND 2200 UTC...THE BUOY REPORTED A MINIMUM PRESSURE OF 1004 MB ALONG WITH PEAK 1-MINUTE WINDS OF 37 KNOTS...SUGGESTING A MINIMUM PRESSURE AROUND 1001 MB. SINCE THAT TIME...THUNDERSTORM ACTIVITY NEAR THE CENTER HAS BECOME BETTER ORGANIZED AND CLOUD TOP TEMPERATURES HAVE GENERALLY COOLED. DVORAK SATELLITE CLASSIFICATIONS FROM SAB AND TAFB WERE A SUBTROPICAL ST2.5. GIVEN THESE DATA AND THE FACT THAT THE SYSTEM IS CENTERED UNDERNEATH AN UPPER TROPOSPHERIC CYCLONE... THE LOW IS BEING DESIGNATED AS A SUBTROPICAL STORM AT THIS TIME WITH AN INITIAL INTENSITY OF 40 KT. THE INITIAL MOTION ESTIMATE IS 015/08...THOUGH RECENT FIXES SUGGEST THAT THE FORWARD SPEED MAY BE SLOWING. A MIDDLE- TO UPPER-LEVEL TROUGH LIFTING OUT OF THE NORTHEASTERN STATES IS TEMPORARILY LEAVING BERYL IN A REGION OF WEAK STEERING. HOWEVER...GLOBAL MODELS AGREE THAT BERYL WILL TURN WEST-SOUTHWESTWARD OR SOUTHWESTWARD WITH AN INCREASE IN FORWARD SPEED DURING THE NEXT COUPLE OF DAYS AS IT STEERED AROUND THE EASTERN PERIPHERY OF A STRONG MID-LEVEL HIGH FORECAST TO BUILD OVER THE LOWER MISSISSIPPI VALLEY. THIS MOTION SHOULD BRING BERYL INLAND OVER A PORTION OF THE SOUTHEASTERN U.S IN ABOUT 2 DAYS...WHERE IT SHOULD BRIEFLY STALL. ALTHOUGH THE SPREAD IN THE GUIDANCE INCREASES AFTER THIS TIME...ALL THE MODELS SHOW A DEEP LONGWAVE TROUGH MOVING FROM THE PLAINS TO THE GREAT LAKES IN THE 3-5 DAY PERIOD. THIS SHOULD CAUSE BERYL TO TURN EAST- NORTHEASTWARD WITH SOME ACCELERATION...WITH THE CENTER LIKELY EMERGING OVER WESTERN ATLANTIC WATERS BY THE END OF THE FORECAST PERIOD. THE OFFICIAL NHC FORECAST TRACK REPRESENTS A BLEND OF THE MORE RELIABLE ECMWF AND GFS SOLUTIONS AND IS A BIT SOUTH OF THE MULTI-MODEL CONSENSUS. THE PROXIMITY OF BERYL TO AN UPPER-LEVEL COLD LOW MAY SLOW ITS ABILITY TO TRANSITON TO A TROPICAL CYCLONE. MARGINALLY WARM WATERS AND DRY AIR IN THE VICINITY OF THE CYCLONE COULD ALSO IMPEDE ITS INTENSIFICATION...ALONG WITH A PERSISTENT NORTHWESTERLY VERTICAL WIND SHEAR FORECAST OVER THE STORM. ONE POSITIVE FACTOR COULD BE THE PASSAGE OF BERYL OVER WARM GULF STREAM WATERS WHICH COULD POTENTIALLY PROVIDE IT WITH A MOMENTARY BOOST. THE OFFICIAL NHC INTENSITY FORECAST CLOSELY FOLLOWS THE STATISTICAL GUIDANCE WHICH SHOWS ONLY SLOW INTENSIFICATION...FOLLOWED BY WEAKENING ONCE THE CENTER MOVES INLAND. FORECAST POSITIONS AND MAX WINDS INIT 26/0300Z 32.5N 74.8W 40 KT 45 MPH 12H 26/1200Z 32.3N 75.6W 40 KT 45 MPH 24H 27/0000Z 31.4N 77.1W 45 KT 50 MPH 36H 27/1200Z 30.5N 79.1W 45 KT 50 MPH 48H 28/0000Z 30.2N 81.0W 45 KT 50 MPH...TROPICAL 72H 29/0000Z 30.5N 83.1W 30 KT 35 MPH...INLAND 96H 30/0000Z 31.2N 82.1W 25 KT 30 MPH...INLAND 120H 31/0000Z 32.5N 78.0W 30 KT 35 MPH...OVER WATER $$ FORECASTER KIMBERLAIN |
