000 WTNT44 KNHC 132053 TCDAT4 TROPICAL STORM IKE DISCUSSION NUMBER 51 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL092008 500 PM EDT SAT SEP 13 2008 IKE IS STEADILY WINDING DOWN AS A TROPICAL STORM...AND SURFACE OBSERVATIONS AND DOPPLER VELOCITY DATA INDICATE THAT IKE IS BARELY ABOVE TROPICAL STORM THRESHOLD...DESPITE THE RATHER LOW PRESSURE OF 980.7 MB RECENTLY REPORTED AT TYLER TEXAS. ADDITIONAL WEAKENING SHOULD OCCUR AS IKE MOVES FARTHER INLAND OVER NORTHEASTERN TEXAS...AND THE CYCLONE COULD WEAKEN INTO A TROPICAL DEPRESSION BEFORE THE CENTER REACHES SOUTHWESTERN ARKANSAS LATER TONIGHT. IKE IS FORECAST OT MERGE WITH A STOUT COLD FRONT IN 24 TO 36 HOURS... AFTER WHICH THE CYCLONE COULD BECOME A FAIRLY STRONG MID-LATITUDE LOW PRESSURE SYSTEM OVER THE UPPER-MIDWEST...AND THEN OVER THE NORTHEASTERN UNITED STATES IN 48 HOURS. THE INITIAL MOTION ESTIMATE IS 010/16. IKE CONTINUES TO ROUND THE WESTERN PERIPHERY OF A STRONG SUBTROPICAL RIDGE CENTERED OVER GEORGIA AND SOUTH CAROLINA. THE NHC MODEL GUIDANCE IS IN STRONG AGREEMENT ON A RAPID NORTHEASTWARD TRACK THROUGH ARKANSAS... MISSOURI...ILLINOIS..AND INDIANA FOR THE NEXT 24 TO 36 HOURS. HOWEVER...THE OFFICIAL FORECAST TRACK IS A LITTLE SLOWER THAN MANY OF THE GLOBAL MODELS IN ANTICIPATION OF THE MID- AND UPPER-LEVEL CIRCULATIONS BECOMING DECOUPLED FROM THE LOW-LEVELS...AND THEN ACCELERATING RAPIDLY NORTHEASTWARD UNDER THE INFLUENCE OF HOSTILE VERTICAL SHEAR CONDITIONS OF MORE THAN 110 KT. THE FORECAST TRACK IS SIMILAR TO THE PREVIOUS ADVISORY...AND THE TIMING OF EXTRATROPICAL TRANSITION IS BASED ON INPUT FROM THE NOAA HYDROMETEOROLOGICAL PREDICTION CENTER. ALTHOUGH IKE IS QUICKLY DEGENERATING AS A TROPICAL CYCLONE... ATMOSPHERIC CONDITIONS ARE GRADUALLY BECOMING MORE FAVORABLE FOR TORNADOES TO DEVELOP ACROSS MUCH OF EASTERN TEXAS...WESTERN LOUISIANA...AND ARKANSAS THROUGH TONIGHT. LOCALLY HEAVY RAINFALL PRODUCING FLOODING WILL REMAIN A THREAT AS WELL. FORECAST POSITIONS AND MAX WINDS INITIAL 13/2100Z 32.4N 95.3W 40 KT...INLAND 12HR VT 14/0600Z 35.1N 93.9W 30 KT...INLAND 24HR VT 14/1800Z 38.9N 88.9W 30 KT...EXTRATROPICAL INLAND 36HR VT 15/0600Z 43.0N 80.3W 30 KT...EXTRATROPICAL INLAND 48HR VT 15/1800Z...ABSORBED BY FRONTAL ZONE $$ FORECASTER STEWART