000 AGXX40 KNHC 210721 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 321 AM EDT TUE APR 21 2009 MARINE WEATHER DISCUSSION FOR GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. GULF OF MEXICO... A DEEP TROUGH OVER THE E CONUS CONTINUES TO DIG INTO THE GULF AS A STRONG UPPER LEVEL JET MAXIMUM OVER THE UPPER MIDWEST DIVES SOUTHEASTWARD INTO THE BASE OF THE TROUGH. AN ASSOCIATED COLD FRONT NOW EXTENDS FROM NEAR TAMPA TO THE YUCATAN PENINSULA... WITH NW TO N WINDS OF 15 TO 20 KT IN THE WAKE OF THE FRONT...HIGHEST OVER THE BAY OF CAMPECHE AND TO THE NW OF A NEWLY FORMED COLD FRONT OVER THE FAR NE GULF. THE FRONT IS FORECAST TO HAVE MOVED SE OF THE GULF BY EARLY THIS AFTERNOON WITH SURFACE HIGH PRESSURE TRANSLATING EASTWARD ACROSS THE N GULF FOR INTO WED AND THU. SE RETURN FLOW AROUND THIS HIGH IS FORECAST TO INCREASE OVER THE W GULF BY LATE WEEK...WITH A LARGE AREA OF 20-25 KT WINDS FRI AND SAT ACROSS THE GULF REGION. THESE WINDS WILL BUILD SEAS TO 6 TO 8 FT BY SAT ACROSS THE MIDDLE AND WEST GULF. SW N ATLC... THE MAIN FORECAST CONCERN IS THE COLD FRONT NOW PUSHING OFF THE SE CONUS COAST. SOUTHERLY WINDS CONTINUE TO INCREASE AHEAD OF THE FRONT...WITH THE QUIKSCAT PASS AROUND 21/2300 UTC INDICATING WINDS TO 25 KT AS FAR SOUTH AS 30N. SOUTHERLY WINDS OF 20-30 KT ARE EXPECTED N OF 25N E OF THE FRONT TODAY AS IT TRACKS WEST-TO-EAST ACROSS THE DISCUSSION AREA. INCREASING UPPER LEVEL SUPPORT WILL FORCE INCREASING PRESSURE FALLS IN THE VICINITY OF THE FRONT TODAY AS IT TRACKS WEST-TO-EAST ACROSS THE REGION. THIS WILL SERVE TO STEEPEN THE PRESSURE GRADIENT BETWEEN THE FRONT AND THE SURFACE RIDGE TO ITS EAST...WITH CONCERN INCREASING FOR A PERIOD OF GALES N OF 30N E OF THE FRONT. TIME HEIGHT ANALYSES AND CROSS SECTIONS ALONG 30.5N E OF THE FRONT DEPICT WINDS AT OR ABOVE GALE FORCE NEARING THE SURFACE BASED ON RECENT OPERATIONAL MODEL GUIDANCE. HOWEVER...THIS GUIDANCE COULD BE TOO AGGRESSIVE IN MIXING THESE WINDS TO THE SURFACE GIVEN WEAK LOW LEVEL LAPSE RATES RESULTING FROM THE WARM AIR ADVECTION OVER RELATIVELY WARMER WATERS. ALSO...ENSEMBLE GUIDANCE INDICATES LOW PROBABILITIES OF GALES REACHING THE FORECAST AREA AT THIS TIME. THUS...THE LATEST FORECAST HAS INCREASED SOUTHERLY WINDS AHEAD OF THE FRONT TO 30 KT...THOUGH THE POTENTIAL FOR GALES WILL CONTINUE TO BE MONITORED. IN THE WAKE OF THE FRONT...WINDS WILL BECOME W TO NW AT 15 TO 20 KT. HOWEVER...A REINFORCING FRONT MOVING OFF THE GEORGIA COAST EARLY WED WILL BRING A BRIEF PERIOD OF 20 TO 25 KT WINDS TO THE NW DISCUSSION AREA LATE WED. THIS FRONT WILL TRACK OVER THE N PORTION OF THE DISCUSSION AREA WHILE MERGING WITH THE INITIAL FRONT FURTHER TO THE E. SEAS TO 10 FT ARE FORECAST N OF 29N E OF THE FRONT THROUGH WED...THOUGH THEY WILL SUBSIDE AS THE WINDS AROUND THE FRONT DIMINISH THEREAFTER. STRONG SURFACE HIGH PRESSURE BUILDING OVER THE W ATLC AND SE CONUS BY LATE WEEK WILL INCREASE NE TO E WINDS TO 20 TO 25 KT ACROSS AREAS S OF 28N...INCLUDING THE BAHAMAS. THESE WINDS WILL BUILD SEAS TO 6 TO 8 FT. CARIBBEAN AND TROPICAL N ATLC... FRESH TO STRONG TRADES WILL AFFECT MUCH OF THE AREA FOR THE REMAINDER OF THE WEEK INTO THE WEEKEND. SURFACE HIGH PRESSURE OVER THE CENTRAL ATLC WILL FOCUS THE STRONGEST OF THESE WINDS S OF 18N AND OVER THE EASTERN TWO-THIRDS OF THE AREA THROUGH THURSDAY. THEREAFTER...A COLD FRONT MOVING ACROSS THE CENTRAL ATLC AND BUILDING HIGH PRESSURE OVER THE SE CONUS AND SW NORTH ATLC WILL FOCUS THE STRONGEST TRADES OVER THE WESTERN HALF OF THE AREA...WITH WINDS INCREASING THROUGH THE WINDWARD PASSAGE INTO SAT. THE STRONGEST WINDS WILL BE FOUND NEAR THE COAST OF COLOMBIA...WHERE THEY WILL REACH 30 KT THROUGH THE WEEKEND. WHILE SLIGHTLY STRONGER WINDS COULD PERIODICALLY OCCUR NEAR THE COAST OF COLOMBIA...GALE FORCE WINDS ARE NOT EXPECTED AT THIS TIME DUE TO RELATIVELY WEAK LAPSE RATES BETWEEN THE SURFACE AND STRONGER WINDS ALOFT. THE TRADES WILL BUILD WAVES TO AT LEAST 8 FT S OF 15N...WITH SEAS OF 9-12 FT NEAR THE COAST OF COLOMBIA. ATLC... .NONE.. CARIBBEAN... .NONE. GULF OF MEXICO... .NONE. FORECASTER COHEN. TROPICAL PREDICTION CENTER.