Official Discussion issued by the National Hurricane Center
IKE (AL092008) DATA RELEASED: 9/5/2008 3:00:00 PM UTC
Copy of official data HURRICANE IKE DISCUSSION NUMBER 18 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL092008 1100 AM EDT FRI SEP 05 2008 NORTHERLY SHEAR CONTINUES TO A TAKE A TOLL ON IKE. SATELLITE IMAGES SHOW THAT THE EYE HAS BECOME LESS CLEAR AND THAT MOST OF THE CONVECTION IS IN THE SOUTHERN SEMICIRCLE. IN ADDITION...A RECENT SSMIS MICROWAVE IMAGE SHOWS THAT THE EYEWALL IS OPEN ON THE NORTH SIDE. USING A BLEND OF THE OBJECTIVE AND SUBJECTIVE DVORAK CLASSIFICATIONS...THE INITIAL INTENSITY IS LOWERED TO 105 KT...AND THIS COULD BE GENEROUS. AN AIR FORCE RESERVE RECONNAISSANCE PLANE IS SCHEDULED TO INVESTIGATE THE HURRICANE THIS AFTERNOON TO OBTAIN A BETTER ESTIMATE OF THE CURRENT INTENSITY AND WIND RADII. ALMOST ALL OF THE GLOBAL MODELS SHOW DECREASING SHEAR OVER IKE IN ABOUT A DAY DUE TO A WEAKENING OF STRONG NORTHEASTERLY UPPER WINDS. EXCEPT FOR A SMALL PATCH OF SSTS NEAR AND NORTH OF THE SOUTHEASTERN BAHAMAS...WATERS ARE VERY WARM ALONG THE FORECAST PATH. THE OFFICIAL FORECAST SHOWS A SLOW WEAKENING OF THE HURRICANE DUE TO THE SHEAR FOR THE FIRST 24 HOURS...THEN SHOWS INTENSIFICATION AS UPPER-WINDS SLACKEN...IN GENERAL AGREEMENT WITH THE LGEM MODEL. IN A COUPLE DAYS...VERTICAL WIND SHEAR WILL LIKELY BECOME LIGHT...AND CONDITIONS LOOK RATHER FAVORABLE FOR INTENSIFICATION. THE OFFICIAL FORECAST COULD BE CONSERVATIVE IN THE LONGER-RANGE AS THE HWRF AND GFDL SHOW A MORE INTENSE HURRICANE. REGARDLESS OF EXACTLY HOW STRONG IT IS...ALL SIGNS ARE THAT IKE WILL BE A DANGEROUS HURRICANE FOR DAYS TO COME. IKE HAS BEEN MOVING SOUTH OF WEST DURING THE PAST FEW HOURS...ABOUT 260/14. THIS GENERAL TRACK WITH SOME DECREASE IN FORWARD SPEED IS FORECAST OVER THE NEXT 36 HOURS DUE TO A STRONG RIDGE WEDGING INTO BETWEEN IKE AND HANNA. THE RIDGE SHOULD WEAKEN SOMEWHAT IN A COUPLE OF DAYS...STEERING THE HURRICANE MORE TO THE WEST AND EVENTUALLY WEST-NORTHWEST. HOWEVER...MODELS ARE NOT IN GOOD AGREEMENT ON WHEN THIS WEST-NORTHWEST MOTION COULD MATERIALIZE. GENERALLY THE MODELS THAT DRIVE THE SYSTEM FARTHER SOUTH...SUCH AS THE ECMWF/HWRF/GFDL MODELS...SUGGEST THE RIDGE WILL REMAIN INTACT ENOUGH TO EVENTUALLY SEND IKE TOWARD CUBA OR THE SOUTHEASTERN GULF OF MEXICO. THE UKMET/GFDN/NOGAPS...ON THE OTHER HAND...SUGGEST THE HURRICANE WILL MOVE MORE THE WEST AND HAS A BETTER CHANCE OF BEING AFFECTED BY A WEAKNESS IN THE RIDGE AROUND 80W. SINCE THE HURRICANE IS MOVING WELL SOUTH OF THE LATTER CLUSTER OF MODELS ALREADY...THE OFFICIAL FORECAST LEANS MORE TOWARD THE SOUTHERN GUIDANCE AND SHIFTED SOUTHWEST OF THE PREVIOUS FORECAST. IT CANNOT BE REPEATED ENOUGH THAT FOUR- AND FIVE-DAY TRACK FORECASTS CAN HAVE SIGNIFICANT ERRORS...AND COMBINED WITH THE FACT THAT THE MODEL SPREAD IS STILL NOTABLE BEYOND 72 HOURS...ONE SHOULD NOT FOCUS ON THE EXACT TRACK. FORECAST POSITIONS AND MAX WINDS INITIAL 05/1500Z 23.2N 62.7W 105 KT 12HR VT 06/0000Z 22.9N 64.7W 95 KT 24HR VT 06/1200Z 22.5N 67.4W 90 KT 36HR VT 07/0000Z 22.2N 69.9W 95 KT 48HR VT 07/1200Z 22.2N 72.5W 105 KT 72HR VT 08/1200Z 23.0N 77.0W 115 KT 96HR VT 09/1200Z 24.0N 80.0W 115 KT 120HR VT 10/1200Z 25.5N 82.0W 100 KT $$ FORECASTER BLAKE |