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| #536338 (Received by flhurricane at: 10:47 AM 23.Aug.2012) TCDAT5 TROPICAL STORM JOYCE DISCUSSION NUMBER 5 NWS NATIONAL HURRICANE CENTER MIAMI FL AL102012 1100 AM AST THU AUG 23 2012 THE CLOUD PATTERN ASSOCIATED WITH THE DEPRESSION HAS INCREASED IN ORGANIZATION THIS MORNING. ANIMATION OF VISIBLE SATELLITE IMAGERY SUGGESTS THAT THE LOW-LEVEL CENTER IS ON THE SOUTH SIDE OF A FAIRLY CIRCULAR MASS OF COLD-TOPPED CONVECTION. DVORAK T-NUMBERS FROM TAFB AND SAB HAVE INCREASED TO A CONSENSUS 2.5...AND THE DEPRESSION IS UPGRADED TO A TROPICAL STORM WITH 35 KT WINDS. THE INITIAL MOTION ESTIMATE IS A STEADY 295/14. GLOBAL MODELS SHOW JOYCE CONTINUING ON A WEST-NORTHWESTWARD COURSE DURING THE NEXT COUPLE OF DAYS...ON THE SOUTH SIDE OF A SUBTROPICAL RIDGE OVER THE CENTRAL ATLANTIC. IN 3-4 DAYS...JOYCE SHOULD REACH THE WESTERN PERIPHERY OF THE RIDGE WHICH SHOULD CAUSE THE STORM TO TURN NORTHWESTWARD AND NORTHWARD. LATE IN THE FORECAST PERIOD...AN AMPLIFYING SHORTWAVE TROUGH MOVING THROUGH THE GREAT LAKES SHOULD ERODE THE WESTERN EXTENSION OF THE RIDGE OVER THE WESTERN ATLANTIC...ALLOWING JOYCE TO RECURVE INTO THE WESTERLIES. THE TRACK GUIDANCE IS IN EXCELLENT AGREEMENT ON THIS SCENARIO...BUT DIFFERENCES ARISE AS A RESULT OF THE FORECAST DEPTH OF THE CYCLONE. THE OFFICIAL TRACK GUIDANCE CONTINUES TO RELY ON A BLEND OF THE ECWMF AND GFS SOLUTIONS...WHICH FAVOR A STRONGER REPRESENTATION OF JOYCE THAN THE GFDL/HWRF SOLUTIONS WHICH HAVE BEEN FORECASTING A MUCH WEAKER SYSTEM. THE INTENSITY FORECAST COULD BE CHALLENGING. THE PROXIMITY OF JOYCE TO A MID- TO UPPER-LEVEL LOW AND ASSOCIATED TROUGH TO THE WEST IS IMPARTING SOUTHERLY SHEAR OVER THE CYCLONE. A DRY SAHARAN AIR LAYER WITHIN THE TROUGH IS ALSO WRAPPING AROUND THE SOUTHWESTERN PART OF THE CIRCULATION. WITH THE CYCLONE FORECAST TO GET CLOSER TO THE TROUGH IN THE NEXT COUPLE OF DAYS...LITTLE ADDITIONAL INTENSIFICATION IS EXPECTED IN THE SHORT TERM. IN ABOUT 4 DAYS...GLOBAL MODELS SHOW THE POSSIBILITY OF A DECREASE IN SHEAR OVER JOYCE IF IT IS FAR ENOUGH AWAY FROM THE UPPER-LEVEL OUTFLOW OF ISAAC. THE OFFICIAL NHC FORECAST IS SIMILAR TO BUT A LITTLE BELOW THE LGEM/SHIPS OUTPUT...SHOWING LITTLE CHANGE IN STRENGTH IN THE SHORT-TERM WITH SOME INTENSIFICATION LATER ON. THIS TIES THE SECOND-EARLIEST FORMATION OF THE TENTH NAMED TROPICAL STORM OF A SEASON. IN 2005...TROPICAL STORM JOSE FORMED ON 22 AUGUST AND IN 1995 TROPICAL STORM JERRY FORMED ON THIS DATE. FORECAST POSITIONS AND MAX WINDS INIT 23/1500Z 15.2N 42.2W 35 KT 40 MPH 12H 24/0000Z 16.0N 44.2W 40 KT 45 MPH 24H 24/1200Z 17.1N 46.9W 40 KT 45 MPH 36H 25/0000Z 18.4N 49.6W 40 KT 45 MPH 48H 25/1200Z 19.9N 52.7W 40 KT 45 MPH 72H 26/1200Z 23.9N 59.1W 40 KT 45 MPH 96H 27/1200Z 28.5N 63.7W 45 KT 50 MPH 120H 28/1200Z 33.5N 62.4W 50 KT 60 MPH $$ FORECASTER KIMBERLAIN |
