ZCZC MIATCDAT1 ALL TTAA00 KNHC DDHHMM TROPICAL STORM ALEX DISCUSSION NUMBER 7 NATIONAL WEATHER SERVICE MIAMI FL 11 PM EDT TUE JUL 28 1998 DEEP CONVECTION HAS BLOSSOMED A LITTLE THIS EVENING NEAR THE CIRCULATION CENTER AND IN A BAND IN THE EASTERN SEMICIRCLE. THIS DEVELOPMENT...ALONG WITH TAFB AND SAB GIVING DVORAK TECHNIQUE T-NUMBERS OF 2.5...SUPPORT UPGRADING THE SYSTEM TO TROPICAL STORM ALEX WITH 35 KT WINDS. THE SPURT IN FORWARD SPEED NOTED EARLIER TODAY SEEMS TO HAVE ENDED AND INITIAL MOTION IS NOW ESTIMATED AT 280/18 KT. WATER VAPOR IMAGERY SHOWS A LARGE CYCLONIC CIRCULATION WITH MULTIPLE VORTICES TO THE NORTH TO NE OF THE TROPICAL STORM. THE 12Z AVN HAS THIS FEATURE PRIMARILY IN THE UPPER ATMOSPHERE...PERHAPS MOST DISTINCT NEAR 300 MB. AT 500 MB...IT SHOWS A WESTWARD RETROGRESSION OF AN ANTICYCLONE FROM 35-40W TO 55-60W OVER THE NEXT 72 HOURS...BUT INDICATES THAT THE HIGH WILL NOT BE STRONG ENOUGH TO PREVENT ALEX FROM GRADUALLY ACQUIRING A GREATER NORTHWARD COMPONENT. THE TRACK GUIDANCE IS CONSISTENT WITH THAT IDEA...AS IS THE OFFICIAL FORECAST WHICH IS A LITTLE TO THE LEFT OF THE PREVIOUS NHC FORECAST. FURTHER DECELERATION IS ALSO PREDICTED. ALTERNATELY...THE 12Z NOGAPS SHOWS THE RETROGRADING HIGH TO BE STRONGER...AND KEEPS THE STORM AT FAIRLY LOW LATITUDE...LOCATED ABOUT 200 NM SOUTH OF OUR FORECAST POINT AT 72 HOURS. ALTHOUGH SOME MID-LEVEL MOISTURE APPEARS TO BE HEADING NORTHEASTWARD AWAY FROM THE CENTER...MOST FACTORS INFLUENCING INTENSITY...AS INDICATED BY THE SHIPS INTENSITY FORECAST GUIDANCE...POINT TOWARD STRENGTHENING. A SHIP REPORT OF 10 KT 150 NM TO THE SOUTHEAST OF THE SYSTEM AT 18Z SUGGESTS THAT THE WIND RADII ARE NOT TOO LARGE AS YET...AT LEAST IN THAT PART OF THE CIRCULATION. RAPPAPORT FORECAST POSITIONS AND MAX WINDS INITIAL 29/0300Z 13.8N 37.8W 35 KTS 12HR VT 29/1200Z 14.3N 40.4W 40 KTS 24HR VT 30/0000Z 15.0N 43.4W 50 KTS 36HR VT 30/1200Z 15.8N 45.9W 55 KTS 48HR VT 31/0000Z 16.8N 48.2W 60 KTS 72HR VT 01/0000Z 19.5N 51.5W 60 KTS NNNN