Hurricane IKE
ZCZC MIATCDAT4 ALL TTAA00 KNHC DDHHMM HURRICANE IKE DISCUSSION NUMBER 10 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL092008 500 PM EDT WED SEP 03 2008 AS ANTICIPATED...IKE HAS CONTINUED TO STRENGTHEN AND ALL SATELLITE-BASED ESTIMATES SAY IT HAS BECOME A HURRICANE. SINCE THE 1800 UTC DVORAK ESTIMATES OF 65 KT...AN EYE HAS BECOME APPARENT IN LATE-DAY VISIBLE IMAGERY...SO THE INTENSITY IS SET TO 70 KT. THE CYCLONE IS INTENSIFYING WITHIN A COCOON OF NEARLY ZERO VERTICAL WIND SHEAR...IN BETWEEN THE DEEP-LAYER LOW OVER THE NORTHWESTERN ATLANTIC AND AN UPPER-LEVEL TROUGH DOMINATING THE EASTERN PORTION OF THE BASIN. WATER VAPOR IMAGERY REVEALS THAT THE UPPER-LEVEL NORTHERLIES ALONG THE WESTERN FLANK OF THE EASTERN TROUGH ARE STARTING TO JUST SLIGHTLY RESTRICT IKE'S OUTFLOW. GLOBAL MODELS FORECAST THE SHEAR TO INCREASE FROM THE EAST...BUT PROBABLY NOT QUICKLY ENOUGH TO HALT IKE'S INTENSIFICATION TREND IN THE SHORT TERM. THE NEW OFFICIAL FORECAST SHOWS AN INTERMEDIATE INTENSITY PEAK AT 24 HOURS PRIOR TO THE ONSET OF THE SHEAR...FOLLOWED BY SLIGHT WEAKENING UNTIL THE SHEAR ABATES AFTER IKE GETS FARTHER WEST. BY THAT TIME...IN ABOUT 72 HOURS...OCEAN AND ATMOSPHERIC FACTORS BECOME QUITE CONDUCIVE FOR INTENSIFICATION...AND THE DYNAMICAL MODELS GFDL AND HWRF...FORECAST A MAJOR HURRICANE BY DAYS 4 AND 5...WHICH IS ALSO SHOWN IN THE OFFICIAL FORECAST. LONG-RANGE INTENSITY FORECASTS ARE RATHER UNCERTAIN...HOWEVER...AND THE INTENSITY PROBABILITY TABLE INCLUDED IN THIS ADVISORY PACKAGE INDICATES THAT THERE IS ROUGHLY A 50 PERCENT CHANCE THAT IKE WILL BE A MAJOR HURRICANE FOUR AND FIVE DAYS FROM NOW. IF IKE IS WEAKER THAN THE OFFICIAL FORECAST AT DAYS 3-5...THEN THE STATISTICAL-DYNAMICAL MODELS SHIPS AND LGEM WILL TURN OUT TO BE MORE ACCURATE. THE HURRICANE CONTINUES HEADING WEST-NORTHWESTWARD OR 290/16. AS THE LARGE AND DEEP-LAYER LOW CURRENTLY JUST OFF THE NORTHEAST U.S. COAST DEPARTS TO THE NORTHEAST...MID-LEVEL RIDGING WILL BUILD OVER THE WESTERN ATLANTIC...WHICH WILL PUSH IKE GENERALLY WESTWARD DURING THE NEXT SEVERAL DAYS. UNDULATIONS IN THE TRACK ARE LIKELY THOUGH. IKE SHOULD CONTINUE WEST-NORTHWESTWARD UNTIL THE WESTERN ATLANTIC RIDGE FORMS...AFTER WHICH THE TROPICAL CYCLONE WILL GRADUALLY ROUND THAT RIDGE. THE BIG QUESTION AT LONGER RANGES IS IF AND WHEN IKE WILL ROTATE AROUND THE WESTERN PERIPHERY OF THAT RIDGE...WHICH WILL DETERMINE WHETHER IKE DIRECTLY AFFECTS ANY LAND AREAS. THE MODELS DO NOT PROVIDE AN UNANIMOUS ANSWER...WHICH IS NOT SURPRISING THIS FAR IN ADVANCE. ALL OF THE MODELS DO SHOW THE BEGINNINGS OF A MOTION NORTH OF DUE WEST BY DAY 5...BUT IT IS TOO EARLY TO DETERMINE IF THIS IS THE START OF RECURVATURE...OR IF ENOUGH RIDGING WILL REMAIN BEYOND DAY 5 TO KEEP IKE MOVING GENERALLY WESTWARD. FORECAST POSITIONS AND MAX WINDS INITIAL 03/2100Z 21.6N 52.7W 70 KT 12HR VT 04/0600Z 22.6N 55.1W 75 KT 24HR VT 04/1800Z 23.8N 57.9W 85 KT 36HR VT 05/0600Z 24.3N 60.4W 80 KT 48HR VT 05/1800Z 23.8N 63.1W 80 KT 72HR VT 06/1800Z 22.5N 68.0W 90 KT 96HR VT 07/1800Z 22.5N 72.0W 100 KT 120HR VT 08/1800Z 23.5N 76.0W 100 KT $$ FORECASTER KNABB NNNN
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