Official Discussion issued by the National Hurricane Center
IKE (AL092008) DATA RELEASED: 9/2/2008 3:00:00 PM UTC
Copy of official data TROPICAL STORM IKE DISCUSSION NUMBER 5 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL092008 1100 AM EDT TUE SEP 02 2008 CONVENTIONAL SATELLITE IMAGERY SHOWS THAT IKE HAS A COMPACT AND WELL-DEFINED CIRCULATION ALTHOUGH DEEP CONVECTIVE BANDING HAS PRIMARILY BEEN LIMITED TO THE EASTERN SEMICIRCLE. A 0847 UTC QUIKSCAT PASS REVEALED THAT THE AREA OF TROPICAL STORM FORCE WINDS HAS EXPANDED A BIT...AND A FEW 50-55 KT BARBS WERE LOCATED WITHIN THE MAIN CONVECTIVE BAND TO THE NORTHEAST OF THE CENTER. SINCE DVORAK T-NUMBERS REMAIN 3.0 FROM TAFB AND SAB...THE INITIAL INTENSITY IS RAISED CONSERVATIVELY TO 50 KT. MODEL GUIDANCE REMAINS IN EXCELLENT AGREEMENT REGARDING THE TRACK OF IKE. MOST MODELS...EXCEPT FOR THE GFDN...ARE TIGHTLY CLUSTERED WITHIN THE FIRST 48 HOURS THEN ONLY SLIGHTLY DIVERGE BEYOND THAT TO DAY 5. IN FACT...WITH A LATITUDINAL SPREAD OF ONLY 5 DEGREES AT DAY 5...WE COULDN'T HAVE ASKED FOR BETTER AGREEMENT IN THE GUIDANCE. THE STORM HAS INCREASED IN FORWARD SPEED WITH AN AVERAGE MOTION OF 280/16. THIS GENERAL MOTION IS EXPECTED THROUGH THE FORECAST PERIOD AS IKE IS STEERED BY A MID-LEVEL HIGH THAT WILL MOVE WEST IN TANDEM WITH THE CYCLONE. SOME OF THE MODELS... PARTICULARLY THE GFDL AND HWRF...SHOW A SLIGHT SOUTHWARD BEND AND BRING IKE VERY CLOSE TO OR OVER HISPANIOLA. HOWEVER...BOTH OF THESE MODELS BRING IKE TO A MAJOR HURRICANE...AND SINCE THE OFFICIAL INTENSITY FORECAST DOES NOT CALL FOR SUCH STRENGTHENING...I PREFER TO REMAIN CLOSER TO THE CONSENSUS OF THE OTHER MODELS. THE TOTAL PRECIPITABLE WATER PRODUCT INDICATES THAT RELATIVELY DRY AIR ALMOST COMPLETELY SURROUNDS IKE. GIVEN THE SMALL SIZE OF THE SYSTEM...IT IS PROBABLY MORE SUSCEPTIBLE TO THE DRY AIR AND WILL PROBABLY REMAIN SO UNTIL IT CAN DEVELOP JUST ENOUGH DEEP CONVECTION TO ISOLATE ITSELF. THE STATISTICAL-DYNAMICAL MODELS SUCH AS THE SHIPS AND LGEM INDICATE GRADUAL INTENSIFICATION TO A HURRICANE BEFORE NORTHEASTERLY SHEAR INCREASES OVER THE SYSTEM IN 48 HOURS. THE GFDL AND HWRF APPARENTLY IGNORE SUCH SHEAR AND FORECAST IKE TO BE A MAJOR HURRICANE IN 3-4 DAYS. WHILE THIS CANNOT BE RULED OUT AS A POSSIBILITY...THE OFFICIAL FORECAST REMAINS CLOSE TO THE PREVIOUS FORECAST AND THE INTENSITY CONSENSUS WITH A PEAK INTENSITY OF 90 KT AS THE SYSTEM APPROACHES HISPANIOLA AND THE SOUTHEASTERN BAHAMAS. FORECAST POSITIONS AND MAX WINDS INITIAL 02/1500Z 18.9N 45.0W 50 KT 12HR VT 03/0000Z 19.3N 47.3W 55 KT 24HR VT 03/1200Z 19.9N 50.3W 60 KT 36HR VT 04/0000Z 20.5N 53.5W 70 KT 48HR VT 04/1200Z 21.0N 56.5W 75 KT 72HR VT 05/1200Z 21.5N 62.5W 80 KT 96HR VT 06/1200Z 21.5N 68.5W 85 KT 120HR VT 07/1200Z 21.5N 74.0W 90 KT $$ FORECASTER BERG/KNABB |