ZCZC MIATCDEP5 ALL TTAA00 KNHC DDHHMM TROPICAL STORM ISIS DISCUSSION NUMBER 7 NATIONAL WEATHER SERVICE MIAMI FL 2 AM PDT THU SEP 03 1998 THE LAST AVAILABLE RADAR IMAGE FROM THE MEXICAN WEATHER SERVICE DOPPLER RADAR AT GUASAVE...0413Z...SHOWS THAT THE CENTER OF ISIS IS OVER LAND ABOUT 60 MILES OF LOS MOCHIS. THE INITIAL INTENSITY IS REDUCED TO 55 KNOTS...AND ISIS IS DOWNGRADED TO A TROPICAL STORM. FURTHER WEAKENING IS FORECAST AS THE SYSTEM INTERACTS WITH LAND. THE SYSTEM HAS TAKEN A MORE NORTHERLY HEADING THE LAST SEVERAL HOURS AND THE INITIAL MOTION ESTIMATE IS NOW 350/10 KNOTS. MOST OF THE 00Z TRACK GUIDANCE CONTINUE TO MOVE ISIS ON A GENERAL NORTHWEST COURSE THROUGH 72 HOURS. THE OFFICIAL FORECAST TRACK IS VERY SIMILAR TO THE PREVIOUS PACKAGE AND IS IN CLOSEST AGREEMENT WITH THE MEDIUM BAM MODEL. SATELLITE PICTURES SHOW A BURST OF DEEP CONVECTION WITH TOPS TO -75C INDICATING VERY HEAVY RAINFALL. AS INDICATED PREVIOUSLY THE MAIN IMPACT FROM ISIS WILL BE HEAVY RAINFALL...5 TO 10 INCHES WITH LOCALLY HIGHER AMOUNTS...OVER THE NEXT 12-36 HOURS RESULTING IN POSSIBLE FLASH FLOODS...AND MUDSLIDES IN HIGH TERRAIN. THE OFFICIAL TRACK FORECAST BRINGS THE SYSTEM TO THE MEXICAN-ARIZONA BORDER BETWEEN 36 AND 48 HOURS. WE WILL BE COORDINATING WITH HPC AND THE APPROPRIATE WEATHER OFFICES REGARDING THE RAINFALL THREAT IN THIS REGION. GUINEY FORECAST POSITIONS AND MAX WINDS INITIAL 03/0900Z 26.5N 109.4W 50 KTS 12HR VT 03/1800Z 27.7N 109.9W 30 KTS...INLAND 24HR VT 04/0600Z 29.1N 111.0W 25 KTS...INLAND 36HR VT 04/1800Z 30.7N 112.2W 20 KTS...INLAND 48HR VT 05/0600Z 32.4N 113.4W 20 KTS...INLAND 72HR VT 06/0600Z 35.5N 116.0W 20 KTS...INLAND NNNN