ZCZC MIATCDAT3 ALL TTAA00 KNHC DDHHMM TROPICAL STORM MITCH DISCUSSION NUMBER 7 NATIONAL WEATHER SERVICE MIAMI FL 11 AM EDT FRI OCT 23 1998 MITCH IS NOT STRENGTHENING AT THIS TIME. ALTHOUGH THE LOW-LEVEL CIRCULATION IS WELL DEFINED...THE CONVECTION IS WEAK. UNEXPECTED UPPER-LEVEL WESTERLY WINDS HAVE BECOME ESTABLISHED OVER THE SYSTEM DISRUPTING THE EXCELLENT OUTFLOW WHICH WAS OBSERVED YESTERDAY. INITIAL INTENSITY IS KEPT AT 50 KNOTS IN THIS ADVISORY...BUT A RECONNAISSANCE PLANE WILL DETERMINE IF MITCH HAS WEAKENED AS SUSPECTED. ALL AVAILABLE MODELS SUGGEST THAT AN UPPER-LEVEL ANTICYCLONE SHOULD FORM OVER THE WESTERN CARIBBEAN WITHIN THE NEXT 24 HOURS OR SO. SUCH A PATTERN WOULD PROVIDE EXCELLENT CONDITIONS FOR STRENGTHENING AND IN FACT...BOTH SHIPS AND THE GFDL MODELS BRING MITCH TO A 75- AND 100-KNOT HURRICANE... RESPECTIVELY. HOWEVER...IT IS DIFFICULT TO VISUALIZE SUCH INTENSIFICATION WITH THE PRESENT POORLY DEFINED PATTERN OBSERVED ON SATELLITE IMAGES AND KNOWING THAT THE GLOBAL MODELS TEND TO GET RID OF WESTERLIES TOO FAST. AT THIS TIME...THE OFFICIAL FORECAST CALLS FOR NO CHANGE IN INTENSITY DURING THE NEXT 24 HOURS AND IF MITCH SURVIVES...THEN..STRENGTHENING SHOULD BEGIN. MITCH HAS BEEN NEARLY STATIONARY AND LITTLE MOTION IS FORECAST DURING THE NEXT 12 HOURS. A MID-LEVEL TROUGH LOCATED ALONG THE EAST COAST OF THE UNITED STATES IS FORECAST TO MOVE OUT OF THE AREA AND BE REPLACED BY A RIDGE. CONSEQUENTLY...A SLOW NORTHWEST TRACK SHOULD BEGIN IN ABOUT 24 HOURS. THIS IS CONSISTENT WITH MOST OF THE TRACK MODELS WHICH ARE FORECASTING MITCH TO BE IN THE NORTHWESTERN CARIBBEAN IN 3 DAYS. NO WATCHES OR WARNINGS ARE NECESSARY AT THIS TIME BUT INTERESTS IN THE WESTERN CARIBBEAN SHOULD CLOSELY MONITOR THE PROGRESS OF THIS SYSTEM. AVILA FORECAST POSITIONS AND MAX WINDS INITIAL 23/1500Z 12.7N 77.9W 50 KTS 12HR VT 24/0000Z 12.9N 78.0W 50 KTS 24HR VT 24/1200Z 14.0N 78.2W 50 KTS 36HR VT 25/0000Z 14.8N 78.6W 65 KTS 48HR VT 25/1200Z 16.0N 79.0W 75 KTS 72HR VT 26/1200Z 17.0N 81.0W 80 KTS NNNN