000 AGXX40 KNHC 201706 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 110 PM EDT THU APR 20 2006 MARINE WEATHER DISCUSSION FOR GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. UPPER LEVELS... LONGWAVE TROUGH IS OVER THE ATLANTIC AREA AND A LONGWAVE RIDGE IS OVER THE EASTERN GULF OF MEXICO. THESE SYSTEMS WILL MOVE EAST WITH THE TROUGH PASSING EAST OF 60W FRIDAY NIGHT AND THE RIDGE MOVING OVER THE WESTERN PART OF THE ATLANTIC AREA FRIDAY NIGHT. A STRONG SHORTWAVE WILL ENTER THE GULF OF MEXICO AREA FRIDAY AND MOVE ACROSS THE SOUTHEAST U.S. THROUGH SATURDAY NIGHT WHEN IT WILL MOVE OFF THE SOUTHEAST U.S. COAST. SHORTWAVE WILL CONTINUE TO MOVE EAST ACROSS THE ATLANTIC AREA SUNDAY AND MONDAY WITH A RIDGE BUILDING OVER THE GULF OF MEXICO IN THE WAKE OF THE SHORTWAVE. THE SHORTWAVE WILL PASS EAST OF 65W MONDAY WITH A BROAD TROUGH OVER THE ATLANTIC AREA. ON TUESDAY THE BROAD TROUGH WILL WEAKEN AS THE LONGWAVE RIDGE OVER THE GULF OF MEXICO EXPENDS EASTWARD OVER THE ATLANTIC AREA COVERING BOTH THE GULF AND ATLANTIC AREAS LATE TUESDAY. SURFACE... RIDGE WILL BUILD OVER THE ATLANTIC WITH INCREASING RETURN FLOW OVER THE WESTERN GULF OF MEXICO AND INCREASING TRADES ESPECIALLY IN THE SOUTHERN CARIBBEAN WHERE WINDS OF UP TO 30 KNOTS WILL DEVELOP NEAR THE COAST OF COLOMBIA BY FRIDAY. RIDGE WILL MOVE EAST IN ADVANCE OF THE ABOVE MENTIONED SHORTWAVE WITH THE SOUTHERLY FLOW OVER THE GULF OF MEXICO DECREASING. THE TRADES IN THE CARIBBEAN WILL CONTINUE STRONG. THE SURFACE FRONT ASSOCIATED WITH THE SHORTWAVE WILL BE WEAK WITH ONLY A WEAK HIGH PRESSURE BEHIND THE FRONT. WINDS ASSOCIATED WITH THE FRONT WILL BE LIGHT BEHIND THE FRONT WITH MODERATE SOUTHERLY FLOW AHEAD OF THE FRONT AS IT MOVES ACROSS THE GULF SATURDAY AND BY SATURDAY NIGHT INCREASING SOUTHERLY WINDS WILL BE OVER THE NORTHWEST PART OF THE ATLANTIC AREA. THE FRONT WILL WEAKEN AS IT MOVES THROUGH THE ATLANTIC WATERS AND A RIDGE WILL BUILD OVER THE ATLANTIC AREA MONDAY. THIS WILL AGAIN INCREASE THE SOUTHERLY RETURN FLOW OVER THE WESTERN GULF OF MEXICO MONDAY AND TUESDAY. TRADES IN THE CARIBBEAN WEAKEN SOME TUESDAY. WARNINGS... ATLANTIC... NONE. CARIBBEAN... NONE. GULF OF MEXICO... NONE. FORECASTER LL