000 AGXX40 KNHC 271634 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1235 PM EDT FRI JUL 27 2012 MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. GULF OF MEXICO... THE MID LEVEL TROUGH OVER THE NE GULF WILL LINGER THROUGH MON...SHIFTING SLOWLY WESTWARD INTO THE N CENTRAL GULF AHEAD OF A COLD FRONT THAT WILL NOT MOVE AS FAR S AS THE GULF COAST. THE SHOWERS AND TSTMS WILL CONTINUE TO IMPACT THE N GULF NEAR THIS TROUGHING THROUGH MON. THE RIDGE AXIS THAT SPANS FROM FORT MYERS TO GALVESTON BAY WILL STAY IN PLACE THROUGH SUN AND THEN BEGIN TO ALIGN ITSELF ALONG 26N. THE PRES GRADIENT ON THE S SIDE OF THE RIDGE WILL BE STRENGTHENED TODAY THROUGH SAT AS THE NORTHERN PORTION OF A TROPICAL WAVE PASSES THROUGH THE BAY OF CAMPECHE. HOWEVER...WINDS ARE NOT EXPECTED TO EXCEED 20 KT WITH THE WAVE. THE 06Z GFS WAS RELIED ON FOR MUCH OF THE FORECAST PERIOD...WITH THE EXCEPTION OF THE WINDS ASSOCIATED WITH THE REFLECTION OF THE MID LEVEL TROUGH IN THE NE GULF WHERE A BLEND OF THE GFS AND ECMWF WAS USED TO ACCOUNT FOR UNCERTAINTY WITH THIS FINE-SCALE FEATURE. CARIBBEAN SEA AND TROPICAL N ATLC W OF 55W... HIGH PRES N OF THE AREA HAS BUILT IN BEHIND THE TROPICAL WAVE MOVING THROUGH THE YUCATAN. THIS HIGH PRES IS MAINTAINING FRESH TO STRONG E-NE WINDS ACROSS THE BASIN...WITH THE 0238 UTC ASCAT PASS SHOWING NEAR GALE FORCE WINDS OFF THE COAST OF COLOMBIA. THE GFS IS DOING A REASONABLY GOOD JOB DEPICTING THESE TRADE WINDS. LOOK FOR WINDS TO BACK OFF A NOTCH OVER THE NEXT TWO DAYS AS THE NEXT TROPICAL WAVE ENTERS THE CARIBBEAN AND DIMINISHES THE PRES GRADIENT. THIS TROPICAL WAVE LIES ALONG 55W. THIS WAVE WILL CONTINUE WESTWARD THROUGH THE TROPICAL N ATLC TODAY INTO EARLY SAT MORNING...THE E CARIBBEAN SAT AFTERNOON THROUGH SUN...AND INTO THE WEST CARIBBEAN MON AND TUE. THE WAVE IS EMBEDDED IN AN AREA OF DRY AIR AND AFRICAN DUST THAT IS INHIBITING CONVECTION. WINDS ARE ONLY A MODERATE BREEZE WITH THE SYSTEM. A SIMILAR AIRMASS IS ALSO IMPACTING THE TROPICAL WAVE ALONG 37W. THE CYCLONIC CIRCULATION ASSOCIATED WITH THIS WAVE IS VERY BROAD AND IS BEGINNING TO PICK UP MORE MOISTURE. SOME MODERATE CONVECTION AND LIGHTNING ARE NOW NOTED ALONG THE WAVE FROM 15N-16N. THE 1148 UTC ASCAT PASS SHOWS AN AREA OF 20 KT NE WINDS PRIMARILY W OF THE WAVE FROM 15N TO 19N. THE MODELS SHOW THIS AREA OF WINDS EXPANDING AS THE WAVE MOVES W. THE 06Z GFS AND 00Z UKMET HAVE BACKED OFF ON THE DEVELOPMENT OF A WELL-DEFINED LOW PRES SYSTEM FROM THIS WAVE LIKE EARLIER RUNS HAVE SHOWN. THIS IS A TREND TOWARD THE MORE OPEN WAVE SEEN IN THE ECMWF. THESE THREE MODELS REMAIN IN REASONABLE AGREEMENT ON THE TIMING OF THE SYSTEM. THE GRIDS WERE ADJUSTED TOWARD A BLEND OF THE 06Z GFS AND THE MORE CONSISTENT 00Z ECMWF. SW N ATLC S OF 31N W OF 65W... A WEAKENING STATIONARY FRONT LIES FROM 31N60W TO 27N62W TO 31N71W. SHIP OBSERVATIONS AND THE 1326 UTC ASCAT PASS SHOW WINDS ARE LESS THAN 20 KT NEAR THE BOUNDARY AND THE 1040 UTC JASON2 PASS CONFIRMS SEAS ARE LESS THAN 8 FT. THIS FRONT IS EXPECTED TO DISSIPATE TONIGHT. THE FRONT HAS FORCED THE SUBTROPICAL RIDGE SOUTHWARD FROM ITS USUAL POSITION. THE RIDGE AXIS CURRENTLY EXTENDS ACROSS THE REGION FROM 24N65W TO 26N80W BUT WILL LIFT TO 28N BY MON. MODERATE TO FRESH TRADE WINDS WILL PERSIST S OF THE RIDGE AS THE NORTH END OF TWO TROPICAL WAVES MAKE THEIR WAY THROUGH SE WATERS. THE FIRST WAVE IS EXPECTED TO MOVE THROUGH PUERTO RICO LATE SAT WHILE THE SECOND WAVE WILL PASS PUERTO RICO LATE MON INTO TUE. SEE THE SECTION ABOVE FOR MORE DETAILS ON THESE ATLC TROPICAL WAVES. ASIDE FROM THESE TROPICAL WAVES...THE FORECAST PRIMARILY RELIES UPON THE GFS SOLUTION. NOTE...GRIDDED MARINE FORECAST IS AVAILABLE AT WWW.NHC.NOAA.GOV/TAFB/GRIDDED_MARINE GULF OF MEXICO... .NONE. CARIBBEAN SEA... .NONE. SW N ATLANTIC... .NONE. FOR ADDITIONAL INFORMATION PLEASE VISIT WWW.HURRICANES.GOV/MARINE $$ FORECASTER SCHAUER