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| #519490 (Received by flhurricane at: 4:56 PM 19.Jun.2012) TCDAT3 TROPICAL STORM CHRIS DISCUSSION NUMBER 1 NWS NATIONAL HURRICANE CENTER MIAMI FL AL032012 500 PM EDT TUE JUN 19 2012 CONVECTION ASSOCIATED WITH THE LOW PRESSURE AREA LOCATED WELL SOUTHEAST OF THE CANADIAN MARITIMES HAS ACQUIRED ENOUGH ORGANIZATION AND COVERAGE FOR THE SYSTEM TO BE CLASSIFIED AS A TROPICAL CYCLONE. THIS IS SUPPORTED BY RECENT DVORAK CLASSIFICATIONS OF T2.5 FROM TAFB AND T1.5 FROM SAB. FSU CYCLONE PHASE SPACE DIAGRAMS ALSO SHOW THE SYSTEM AS A SYMMETRIC WARM CORE...ALBEIT SHALLOW...SYSTEM. THE INITIAL WIND SPEED OF 40 KT IS BASED ON EARLIER SCATTEROMETER DATA AND A SHIP THAT REPORTED 35-KT WINDS TO THE SOUTHEAST OF THE CENTER THIS MORNING. THE INITIAL MOTION ESTIMATE IS 090/7. THE TROPICAL STORM IS FORECAST TO ACCELERATE EASTWARD IN THE MID-LATITUDE WESTERLY FLOW DURING THE NEXT DAY OR SO. AFTER THAT TIME...IT IS FORECAST TO TURN NORTHEASTWARD...THEN NORTHWARD AROUND A DEVELOPING CUT-OFF LOW. THE TRACK GUIDANCE IS IN GOOD AGREEMENT ON THIS GENERAL SCENARIO...BUT THERE IS SOME SPREAD AS TO HOW SHARP THE CYCLONE TURNS NORTHWARD. FOR NOW...THE OFFICIAL FORECAST LIES NEAR THE MIDDLE OF THE GUIDANCE ENVELOPE...BETWEEN THE GFS AND ECMWF MODELS. LITTLE CHANGE IN STRENGTH IS EXPECTED DURING THE NEXT DAY OR SO AS CHRIS TRAVERSES THE MARGINALLY WARM WATERS NEAR THE SOUTHERN EDGE OF THE GULF STREAM. THE CYCLONE SHOULD MOVE OVER COLDER WATERS IN 36-48 HOURS...ALTHOUGH GLOBAL MODELS SHOW THE LOW STRENGTHENING AS A BAROCLINIC SYSTEM AT THAT TIME. THE CYCLONE IS LIKELY TO BE ABSORBED BY A LARGER EXTRATROPICAL LOW PRESSURE AREA IN 3 TO 4 DAYS...AND THIS IS REFLECTED IN THE NHC FORECAST. ONLY TWICE BEFORE...IN 1887 AND 1959...HAS THE THIRD STORM OF THE SEASON FORMED EARLIER THAN THIS DATE. FORECAST POSITIONS AND MAX WINDS INIT 19/2100Z 39.3N 57.7W 40 KT 45 MPH 12H 20/0600Z 39.2N 54.8W 40 KT 45 MPH 24H 20/1800Z 39.5N 50.5W 40 KT 45 MPH 36H 21/0600Z 40.9N 46.1W 40 KT 45 MPH...POST-TROP/EXTRATROP 48H 21/1800Z 43.3N 44.1W 45 KT 50 MPH...POST-TROP/EXTRATROP 72H 22/1800Z 45.5N 45.0W 40 KT 45 MPH...POST-TROP/EXTRATROP 96H 23/1800Z...ABSORBED BY EXTRATROPICAL LOW $$ FORECASTER BROWN |
