000 AGXX40 KNHC 230555 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 155 AM EDT TUE SEP 23 2008 MARINE WEATHER DISCUSSION FOR GULF OF MEXICO... CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. UPPER LEVELS... TROUGH OVER ATLANTIC WEST OF 75W AND FLORIDA WILL PERSIST AND EXPAND IN COVERAGE AND INCREASE IN INTENSITY THROUGH FRIDAY THEN ONLY WEAKEN SLIGHTLY SATURDAY. ON FRIDAY THE TROUGH WILL COVER THE AREA NORTH OF 22N FROM 65W TO 90W WITH A CYCLONIC CIRCULATION CENTER OVER THE CAROLINAS. ELSEWHERE WEAK RIDGE OVER THE AREA. SURFACE... RIDGE OVER THE UNITED STATES FROM NEW ENGLAND TO TEXAS WILL CHANGE LITTLE TODAY AND TONIGHT THEN WEAKEN SLIGHTLY THROUGH SATURDAY. BESIDES THE POSSIBLE TROPICAL CYCLONE NEAR THE MONA PASSAGE AND EASTERN REPUPLICA DOMINICANA A BROAD LOW COVERS THE CARIBBEAN. THIS LOW WILL EXPAND NORTHWARD MOSTLY OVER THE WESTERN ATLANTIC WITH AN INCREASING PRESSURE GRADIENT OVER THE NORTHWEST PART OF THE SOUTHWEST NORTH ATLANTIC AND THE NORTHERN GULF OF MEXICO BETWEEN THE RIDGE AND THE EXPANDING LOW. BY FRIDAY THE LOW WILL OCCUPY MOST OF THE ATLANTIC AREA NORTH OF 23N AND THE PRESSURE GRADIENT WILL WEAKEN. ELSEWHERE AND OTHERWISE BESIDES POSSIBLE TROPICAL CYCLONE A WEAK PRESSURE PATTERN WILL BE OVER THE AREA. THE POSSIBLE TROPICAL CYCLONE NEAR THE MONA PASSAGE AND EASTERN REPUPLICA DOMINICANA IS FORECAST TO MOVE LITTLE OR DRIFT SLIGHTLY NORTH TODAY AND TONIGHT. ON WEDNESDAY THE SYSTEM WILL MOVE NORTH REACHING 31N EARLY FRIDAY AND CONTINUE MOVING NORTH. THE SYSTEM IS FORECAST TO STAY EAST OF 70W. DEVELOPMENT OF THE SYSTEM WILL DEPEND ON MANY FACTORS MANY OF WHICH WE KNOW LITTLE. WARNINGS... ATLANTIC... NONE. CARIBBEAN... NONE. GULF OF MEXICO... NONE. FORECASTER LL. TROPICAL PREDICTION CENTER.