000 AGXX40 KNHC 291939 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 340 PM EDT WED JUL 29 2009 MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. GULF OF MEXICO... THE ATLANTIC RIDGE AXIS CONTINUES TO EXTEND FROM A 1031 MB HIGH LOCATED OVER THE W CENTRAL ATLC NEAR 33N56W...W-SW ACROSS CENTRAL FLORIDA AND THEN INTO THE NE GULF ALONG 27/28N. LITTLE OVERALL CHANGE IN THE PATTERN IS EXPECTED THROUGH THIS FORECAST PERIOD...WITH THE RIDGE AXIS FORECAST TO SHIFT SLOWLY NWD OVER THE NEXT SEVERAL DAYS TO ALONG 30/31N BY SUN. A MORNING QUIKSCAT PASS SHOWED SELY WINDS OF AROUND 20 KT ACROSS A LARGE PORTION OF THE WESTERN GULF. WINDS ALONG THE LOWER TEXAS COAST AND UPPER MEXICO HAVE BEGUN TO INCREASE TO NEAR 20 KT DUE TO DIURNAL HEATING. A BROAD AREA OF SAHARAN AIR IS SUGGESTED ACROSS THE SW GULF THIS MORNING...AHEAD OF THE NEXT APPROACHING TROPICAL WAVE ALONG 86/87W...AND WILL PROVIDE THE POTENTIAL FOR STRONG CONVECTIVELY DRIVEN DOWN DRAFTS WITH TSTMS MOVING NW OFF THE YUCATAN AND INTO THE SW GULF THROUGH THIS EVENING. THIS OCCURRED JUST A FEW DAYS AGO TO PRODUCE VERY LARGE ARCH CLOUDS RACING N TO NW IN EXCESS OF 30 KT ACROSS THE W CENTRAL GULF. A PORTION OF THIS TROPICAL WAVE WILL FRACTURE OR SHEAR OFF AND MOVE THROUGH THE BAY OF CAMPECHE LATE THU INTO FRI...AND BRING E-SE 20 KT WINDS AND BUILDING SEAS. SEAS THIS MORNING WERE IN THE 1-3 FT RANGE ACROSS THE NE ONE-THIRD OF THE GULF...AND BETWEEN 3 TO 5 FT OVER THE WEST AND SOUTHWESTERN GULF...WITH HIGHEST SEAS AROUND 5 FT NEAR THE TEXAS COAST. SEAS MAY BUILD UP TO 6 FT THU NIGHT THROUGH SAT OVER THE FAR SE WATERS...AS WELL AS THE STRAITS OF FLORIDA...AS A STRONGER E-SE SURGE OF WINDS BUILDS INTO THE BASIN. CARIBBEAN SEA... STRONG EASTERLY TRADE WINDS CONTINUE TO BLOW ACROSS THE BASIN... PARTICULARLY OVER THE CENTRAL AND W CENTRAL PORTIONS DUE TO THE STRONG SURFACE PRES GRADIENT BETWEEN THE ATLC RIDGE N OF AREA AND THE COLOMBIAN/PANAMANIAN LOW. WINDS ARE ALSO BEING ENHANCED BY LOW LEVEL WIND SURGES ASSOCIATED WITH THE TROPICAL WAVE ACROSS THE W CARIB...AND A NEXT WIND SURGE AND AREA OF SAL DAMMING UP BEHIND IT ASSOCIATED WITH THE LOW AMPLITUDE WAVE APPROACHING THE LESSER ANTILLES. MORNING QSCAT PASSES SHOWED A LARGE AREA OF ENE TO E WINDS OF 25 TO 30 KT COVERING MOST OF THE CENTRAL CARIBBEAN BETWEEN 69W AND 79W...WITH A SMALL AREA OF STRONGER WINDS AS USUAL JUST OFFSHORE THE COLOMBIAN COAST....WHERE QSCAT WINDS AND A LONE SHIP OBSERVATION INDICATED MINIMAL GALE WINDS. I HAVE THUS ISSUED A GALE WARNING FOR THAT AREA THROUGH 12Z THU AS WAS ALSO SUGGESTED BY GFS AND ECMWF. GLOBAL MODELS INDICATE THAT 20-25 KT WINDS WILL LIKELY EXPAND ACROSS THE WESTERN CARIBBEAN S OF 18N LATE THIS AFTERNOON INTO EARLY THU. NE WINDS OF 20 TO 25 KT AND SEAS TO 7 FT WILL ALSO AFFECT THE WINDWARD PASSAGE LATE WED INTO THU. MAXIMUM SWH (SIGNIFICANT WAVE HEIGHT) UP TO 16 FT IN E SWELL ARE EXPECTED TONIGHT THROUGH THU MIDDAY OVER THE SOUTH-CENTRAL CARIBBEAN AS THIS SECOND WIND SURGE MOVES THROUGH THE BASIN. LATEST WAVE MODEL GUIDANCE SHOWS THAT SEAS WILL SUBSIDE SOME OVER MUCH OF THE CARIBBEAN THU NIGHT INTO FRI. THE TROPICAL WAVE APPROACHING THE LESSER ANTILLES THIS MORNING HAS REMAINED BENIGN LOOKING IN RECENT DAYS PER STILT IMAGERY. HOWEVER...GLOBAL MODELS SUGGEST THIS LOW AMPLITUDE WAVE WILL TAKE A MORE W-NW TRAJECTORY AFTER ENTERING THE SE CARIB. AS IT TRACKS MORE W-NW ACROSS THE E CENTRAL AND CENTRAL CARIB THU AND FRI...ASSOCIATED MOISTURE WILL ADVECT NW ON THE BACK SIDE OF THE WAVE...AND BECOME MORE ACTIVE CONVECTIVELY AS IT ENCOUNTERS GENERAL UPPER LEVEL ELYS. ATLANTIC S OF 31N W OF 55W... A RIDGE EXTENDS FROM 33N56W TO CENTRAL FLORIDA INTO THE NE GULF OF MEXICO WHILE A DEEP LAYERED TROUGH IS JUST MOVING OFF THE E COAST OF THE U.S. AND STALLING OFFSHORE OF THE FL PENINSULA. LATEST AND CURRENT SHIP AND BUOY OBSERVATIONS ARE REPORTING S-SW WINDS OF 10-15 KT OFF THE COAST OF FLORIDA...WHILE FARTHER S AND SE...S OF 25N...PERSISTENT E-SE WINDS OF 20-25 KT PREVAIL. SIGNIFICANT WAVE HEIGHTS ARE IN THE 3-5 FT RANGE N OF 25N...WHILE THE ELY TRADE WIND SWELL AFFECTS THE REMAINDER OF THE AREA...WITH SEAS RUNNING 6-7 FT AT 7-8 SECONDS...WITH SMALL POCKETS OF 8 FT BETWEEN THE SE BAHAMAS AND HAITI AND JUST E OF THE LESSER ANTILLES. LITTLE CHANGE IN THE OVERALL SYNOPTIC PATTERN IS ANTICIPATED OVER THE AREA THROUGH THE FORECAST PERIOD AND THE ATLANTIC RIDGE REMAINS IN PLACE. HOWEVER...A SLIGHT SHIFT TO THE N OF THE WRN PERIPHERY OF THE DEEPER LAYERED RIDGE WILL ALLOW A MORE WNW TRAJECTORY OF TROPICAL WAVES ENTERING THE AREA DURING THE NEXT FEW DAYS. A WIND SURGE MOVING ACROSS THE NE CARIB AND LESSER ANTILLES ASSOCIATED WITH THE TROPICAL WAVE APPROACHING THE WINDWARD ISLANDS THIS AFTERNOON WILL TRANSLATE MORE NW AND ACROSS CUBA AND THE BAHAMAS DURING THE NEXT 48 HOURS...AND ENHANCE THE 20 KT FLOW THROUGH THE BAHAMAS AND INTO THE STRAITS OF FLORIDA TO 20-25 KT...WITH POCKETS OF SEAS TO 8 FT. WARNINGS ATLC... .NONE. CARIBBEAN... .GALE WARNING FROM 11N TO 13N BETWEEN 72W AND 78W...AMZ084 GULF OF MEXICO... .NONE. $$ FORECASTER STRIPLING