000 AGXX40 KNHC 090600 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 200 AM EDT MON JUL 09 2012 MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. GULF OF MEXICO... AN E TO W RIDGE EXTENDS ACROSS THE NORTHERN GULF WITH A SURFACE HIGH PRESSURE CENTER OF ABOUT 1016 MB...DEVELOPING OCCASIONALLY ALONG THE RIDGE AXIS OVER THE NE WATERS AS A WEAK N-S TROUGH FORMS OVER THE FL PENINSULA AND EFFECTIVELY SEPARATES THE GULF OF MEXICO SEGMENT OF THE RIDGE FROM ITS PARENT ATLC RIDGE. THE NORTHERN EXTENSION OF A TROPICAL WAVE IS MOVING W THROUGH THE BAY OF CAMPECHE AND HAS INCREASED THE LOW LEVEL WINDS TO 15-20 KT AND ISOLATED TSTMS. THE WAVE AND ITS EFFECTS SHOULD MOVE W OF THE AREA LATE TONIGHT. A SECOND TROPICAL WAVE WILL MOVE INTO THE FL STRAITS THU AND WEAKEN OVER THE THE S-CENTRAL WATERS ON FRI. GUIDANCE DOES NOT SHOW ANY INCREASE IN WINDS WITH THIS 2ND WAVE...BUT SUGGESTS AN INCREASE IN PRECIP. EXPECT SLY RETURN FLOW TO INCREASE TO 15-20 KT OVER THE W-CENTRAL WATERS TONIGHT AND CONTINUE THROUGH LATE WED...WITH THE GRADIENT RELAXING SOME WED NIGHT THROUGH THU. GUIDANCE BEGINS TO DIFFER ON THU NIGHT AND FRI CONCERNING THE EXTENT A WEAK COLD FRONT WILL PENETRATE THE NW WATERS. EXPECT THE FRONT TO STALL FROM SE LA TO THE TX COASTAL BEND MIDDAY FRI WITH SLY FLOW AHEAD OF THE FRONT MAXING AT 15 KT. LIKELY SEE ADJUSTMENTS TO THIS STALLED POSITION IN FUTURE FORECAST CYCLES. BLENDED IN A SMALL PERCENT OF LATEST GFS INTO PREVIOUS FORECAST. SW N ATLC S OF 31N W OF 55W... A RIDGE EXTENDING E TO W FROM 31N55W TO NE FL WILL CHANGE LITTLE TODAY AND TUE...THEN LIFT N TO ALONG 31N ON WED...AND BE POSITIONED N OF AREA THU AND FRI. SW WINDS N OF THE RIDGE WILL CONTINUE AT 10-15 KT...WHILE ELY WINDS S OF 22N W OF 67W WILL CONTINUE IN THE 15-20 KT RANGE THROUGH THE PERIOD. A TROPICAL WAVE CURRENTLY S OF 25N ALONG 63W WILL REACH THE SE BAHAMAS TUE...AND MOVE THROUGH THE CENTRAL BAHAMAS WED...MOVE THROUGH THE FL STRAITS THU...AND INTO THE GULF OF MEXICO THU NIGHT. THE WAVE IS ACCOMPANIED BY ONLY 15 KT NE-E-SE WIND SHIFT AND SCATTERED SHOWERS. BLENDED LATEST GFS INTO PREVIOUS FORECAST. CARIBBEAN SEA AND TROPICAL N ATLC W OF 55W... A TROPICAL WAVE TO THE N OF 15N IS PASSING THROUGH THE LEEWARDS ATTM. THE WAVE SHOULD REACH THE LONGITUDE OF PUERTO RICO LATER TODAY...PASS THROUGH THE HISPANIOLA AREA TUE...AND PASS THROUGH THE NW CARIBBEAN WED-THU NIGHT. ELY TRADES HAVE DIMINISHED TO 25 KT ACROSS THE CENTRAL CARIBBEAN BETWEEN 68W AND 77W...WITH ELY 20 KT OBSERVED ELSEWHERE S OF 17N BETWEEN 65W AND 82W. THE TRADES WILL INCREASE TO 20 KT OVER THE TROPICAL ATLC WATERS S OF 18N TONIGHT...WITH THE INCREASE IN THE EASTERLIES SPREADING W ACROSS THE ENTIRE CARIBBEAN S OF 18N BY LATE TUE NIGHT. AS THE GRADIENT INCREASES ACROSS THE AREA THE LOW LEVEL FLOW WILL INCREASE TO 25-30 KT BRIEFLY AGAIN ALONG THE NW COAST OF COLOMBIA WED AND THU...THEN DIMINISH AGAIN OF FRI. BLENDED LATEST GFS WITH PREVIOUS FORECAST PACKAGE. NOTE...GRIDDED MARINE OUTPUT 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 NELSON