ZCZC MIATCDAT4 ALL TTAA00 KNHC DDHHMM TROPICAL DEPRESSION CHANTAL DISCUSSION NUMBER 25 NATIONAL WEATHER SERVICE MIAMI FL 5 PM EDT TUE AUG 21 2001 SATELLITE IMAGERY AND RADAR OBSERVATIONS FROM BELIZE INDICATE THAT CONVECTION ASSOCIATED WITH CHANTAL HAS DECREASED SIGNIFICANTLY OVER THE PAST SEVERAL HOURS...AND MOST OF THE REMAINING CONVECTION IS OVER THE CARIBBEAN WELL REMOVED FROM THE CENTER. THE CYCLONE IS THUS DOWNGRADED TO A 30 KT DEPRESSION. THE INITIAL MOTION IS NOW 285/6. WATER VAPOR IMAGERY INDICATES A STRONG MID/UPPER LEVEL TROUGH OVER THE EASTERN GULF OF MEXICO... WITH A LARGE ANTICYCLONE DEVELOPING OVER TEXAS AND NORTHERN MEXICO. LARGE-SCALE MODELS INDICATE THIS ANTICYCLONE SHOULD MOVE EASTWARD WITH TIME...WITH CHANTAL FOLLOWING A WESTWARD OR WEST-NORTHWESTWARD TRACK TO ITS SOUTH. NHC HURRICANE GUIDANCE AGAIN AGREES WITH THIS SCENARIO...ALTHOUGH THE MAJOR DIFFERENCES IN SPEED NOTED EARLIER CONTINUE. THE OFFICIAL FORECAST IS BASICALLY AN UPDATE OF THE PREVIOUS PACKAGE SINCE CHANTAL SEEMS TO BE MORE OR LESS ON THE PREVIOUS FORECAST TRACK. CHANTAL SHOULD REMAIN A DEPRESSION WHILE OVER YUCATAN AS THE CIRCULATION IS NOW TOO WELL DEFINED FOR THE SYSTEM TO DISSIPATE DURING THE TIME IT WILL BE OVER LAND. THE CYCLONE HAS BEEN SHOWING ANTICYCLONIC OUTFLOW DURING THE DAY...SO CONDITIONS APPEAR AT LEAST SOMEWHAT FAVORABLE FOR RE-INTENSIFICATION WHEN IT MOVES BACK OVER THE WATER. THE INTENSITY FORECAST IS ALSO AN UPDATE OF THE PREVIOUS PACKAGE...CALLING FOR STRENGTHENING OVER WATER AND RAPID WEAKENING OVER THE MOUNTAINS OF EASTERN MEXICO AFTER LANDFALL. IF THE UPPER LEVEL RIDGE/ANTICYCLONE FORECAST OVER THE BAY OF CAMPECHE BY THE LARGE-SCALE MODELS ACTUALLY DEVELOPS...CHANTAL MAY MAKE YET ANOTHER BID TO BECOME A HURRICANE. TROPICAL STORM WARNINGS AND WATCHES REMAIN IN EFFECT FOR PORTIONS OF THE MEXICAN GULF COAST BASED ON THE FORECAST RE-INTENSIFICATION AFTER CHANTAL MOVES OFFSHORE. FORECASTER BEVEN FORECAST POSITIONS AND MAX WINDS INITIAL 21/2100Z 18.7N 89.7W 30 KTS 12HR VT 22/0600Z 18.9N 90.7W 30 KTS...INLAND 24HR VT 22/1800Z 19.3N 92.4W 35 KTS...OVER WATER 36HR VT 23/0600Z 19.6N 94.3W 45 KTS 48HR VT 23/1800Z 19.8N 96.2W 55 KTS 72HR VT 24/1800Z 20.0N 99.5W 25 KTS...INLAND NNNN