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#8339 (Received by flhurricane at: 5:02 PM 14.Sep.2004) TCDAT1 TROPICAL STORM JEANNE DISCUSSION NUMBER 5 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 PM EDT TUE SEP 14 2004 RECONNAISSANCE...SATELLITE...AND SAN JUAN DOPPLER RADAR DATA INDICATE THAT TROPICAL STORM JEANNE HAS CONTINUED TO STRENGTHEN. THE PRESSURE HAS DECREASED TO 998 MB...DOWN 4 MB IN 2 HOURS. THE INITIAL INTENSITY OF 50 KT IS BASED ON A 1000-FT FLIGHT-LEVEL WIND OF 58 KT...EQUAL TO ABOUT A 46-KT SURFACE WIND...AND THE IMPROVED APPEARANCE IN SATELLITE AND RADAR IMAGERY SINCE THE RECON FIX. THE INITIAL MOTION ESTIMATE IS 290/08...ALTHOUGH THE TWO RECON FIX POSITIONS SUGGEST THE MOTION COULD BE CLOSER TO 285 DEGREES. THE 18Z 500 MB HEIGHT AT SAN JUAN HAS NOT CHANGED IN THE LAST 24 HOURS ...SUGGESTING THAT THE LARGE SUBTROPICAL RIDGE TO THE NORTH IS HOLDING STEADY. ALL OF THE NHC MODEL GUIDANCE...EXCEPT FOR THE BAM MODELS AND NOGAPS...MOVE JEANNE IMMEDIATELY NORTHWESTWARD AND TAKE THE CYCLONE JUST NORTH OF PUERTO RICO. THIS SEEMS UNREALISTIC GIVEN THE PAST 18-HR MOTION OF JEANNE AND THE 18Z SAN JUAN UPPER-AIR DATA. SO IN THE SHORT TERM...JEANNE IS FORECAST TO PASS NEAR THE SOUTH COAST OF PUERTO RICO IN 18-24 HOURS...AND THEN SKIRT THE NORTH COAST OF THE DOMINICAN REPUBLIC AFTER THAT THROUGH 48 HOURS. WHILE THE SPECIFIC SYNOPTIC DETAILS OF THE VARIOUS MODELS DIFFER SIGNIFICANTLY...THERE IS GENERAL AGREEMENT THAT THE RIDGE CURRENTLY LOCATED NORTH OF JEANNE WILL REMAIN INTACT THROUGHOUT THE FORECAST PERIOD. HOWEVER...THE GFS AND GFDL MODELS WEAKEN THE RIDGE ENOUGH TO ALLOW JEANNE TO MOVE ALMOST DUE NORTH AFTER 72 HOURS ALONG 70W LONGITUDE. GIVEN THE GFS RECENT POOR HISTORY OF FORECASTING TOO WEAK OF A RIDGE OVER THE WESTERN ATLANTIC...THE OFFICIAL FORECAST TRACK LEANS MORE TOWARD THE UKMET AND NOGAPS MODELS. IT SHOULD BE POINTED OUT THAT THE CANADIAN AND ECMWF MODELS KEEP A STRONG RIDGE BETWEEN JEANNE AND IVAN THROUGH 120 HOURS...AND TAKE THE CYCLONE WESTWARD TOWARD THE BAHAMAS AND THE FLORIDA PENINSULA. JEANNE HAS DEVELOPED AN EXCELLENT OUTFLOW PATTERN AND THIS IS EXPECTED TO PERSIST UNTIL THE CYCLONE NEARS PUERTO RICO. THIS OUTFLOW PATTERN...COMBINED WITH NEARLY 29C SSTS AND A VERY TIGHT INNER-CORE WIND FIELD AS NOTED IN THE RECON DATA...SHOULD ALLOW JEANNE TO POSSIBLY REACH HURRICANE STRENGTH BEFORE IT REACHES PUERTO RICO. AFTER THAT...CLOSE PROXIMITY TO HISPANIOLA SHOULD INHIBIT STRENGTHENING UNTIL AFTER 72 HOURS...WHEN JEANNE IS FORECAST TO MOVE AWAY FROM HISPANIOLA...AND NORTHERLY VERTICAL SHEAR IS EXPECTED TO WEAKEN AND BECOME EASTERLY IN DIRECTION. FORECASTER STEWART FORECAST POSITIONS AND MAX WINDS INITIAL 14/2100Z 16.8N 63.9W 50 KT 12HR VT 15/0600Z 17.4N 65.3W 55 KT 24HR VT 15/1800Z 18.1N 67.0W 65 KT...INLAND PUERTO RICO 36HR VT 16/0600Z 18.9N 68.6W 65 KT...NEAR DOM. REPUBLIC 48HR VT 16/1800Z 19.7N 70.0W 65 KT...NEAR DOM. REPUBLIC 72HR VT 17/1800Z 20.9N 72.0W 65 KT 96HR VT 18/1800Z 22.5N 74.5W 70 KT 120HR VT 19/1800Z 24.5N 75.5W 75 KT |