ZCZC MIATCDAT1 ALL TTAA00 KNHC DDHHMM TROPICAL STORM ALEX DISCUSSION NUMBER 11 NATIONAL WEATHER SERVICE MIAMI FL 11 PM EDT WED JUL 29 1998 SATELLITE PICTURES OF ALEX SHOW A LESS COHERENT PATTERN THAN 24 HOURS AGO. DEEP CONVECTION IS LIMITED AND NOT WELL ORGANIZED AND THE OVERALL CONFIGURATION...PARTICULARLY AT MID LEVELS...HAS BEEN ELONGATED FROM SOUTHWEST TO NORTHEAST BY AN INTERACTION WITH A COMPLEX CYCLONIC CIRCULATION SEEN NEARBY IN WATER VAPOR IMAGERY. THE INITIAL WIND SPEED FOR THIS ADVISORY IS AGAIN 35 KT. ALEX IS MOVING JUST NORTH OF DUE WEST AT ABOUT 13 KT. WHETHER ALEX HAS A DIRECT IMPACT ON THE LESSER ANTILLES DEPENDS ON HOW SOON AND HOW MUCH THE WESTERN SIDE OF THE ANTICYCLONE TO THE NORTH IS ERODED WHEN THE LONGWAVE TROUGH ALONG THE EAST COAST IS REINFORCED. YESTERDAY...THE 12Z NOGAPS SEEMED TO PROVIDE THE BEST GUIDANCE... KEEPING A STRONGER HIGH TO THE NORTH AND A MORE WESTERLY TRACK THAN SHOWN BY THE OTHER MODELS. THERE IS A SIMILAR DIFFERENCE TODAY WITH THE NEW 18Z AVN NOW ALSO SHOWING A PROLONGED WESTWARD HEADING... THROUGH 36-48 HOURS. IN DEFERENCE TO YESTERDAYS PARTIAL VERIFICATION...THE OFFICIAL FORECAST IS ON THE LEFT SIDE OF THE CLUSTER OF 12Z AVN-BASED TRACKS...BUT NOT AS FAR SOUTH AS THE NOGAPS. INTENSIFICATION IS STILL POSSIBLE AND THE GFDL AND SHIPS SCHEMES BRING ALEX TO THE THRESHOLD OF HURRICANE STRENGTH BY 72 HOURS. THE OFFICIAL FORECAST ALSO SHOWS STRENGTHENING...BUT THIS IS POSTPONED ABOUT A DAY...UNTIL THE PERIOD WHEN THE AVN SHOWS A SOMEWHAT MORE FAVORABLE UPPER-LEVEL PATTERN. RAPPAPORT FORECAST POSITIONS AND MAX WINDS INITIAL 30/0300Z 14.3N 43.2W 35 KTS 12HR VT 30/1200Z 14.5N 45.1W 35 KTS 24HR VT 31/0000Z 15.0N 47.7W 40 KTS 36HR VT 31/1200Z 15.5N 50.6W 45 KTS 48HR VT 01/0000Z 16.5N 53.1W 50 KTS 72HR VT 02/0000Z 18.0N 58.0W 55 KTS NNNN