000 AGXX40 KNHC 040756 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 356 AM EDT TUE AUG 04 2009 MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. GULF OF MEXICO... A PERSISTENT UPPER TROUGH DOMINATING THE ERN U.S. WILL SUPPORT A SERIES OF WEAK FRONTAL TROUGHS MOVING INTO AND THEN STALLING ACROSS THE NE WATERS THROUGH THU. OTHERWISE A WEAK RIDGE WILL MEANDER E TO W OVER THE NORTHERN WATERS THROUGH THE PERIOD. SLY RETURN FLOW WILL PREVAIL AT 10 TO 15 KT OVER THE NW WATERS AND ALONG THE MEXICAN COAST. S TO SW WINDS OVER THE WATERS N OF THE RIDGE AXIS WILL OCCASIONALLY DROP OFF TO LIGHT AND VARIABLE. EXPECT THE DAILY BACKING OF WINDS TO THE N AND NE AT 15 TO 20 KT A FEW HOURS PRIOR TO SUNSET ALONG THE YUCATAN PENINSULA TILL A FEW HOURS AFTER SUNSET. AMPLE MOISTURE WILL MOVE ACROSS THE BAY OF CAMPECHE AND SW GULF TODAY FOR ACTIVE WEATHER. THE NORTHERN PORTION OF A TROPICAL WAVE WILL MOVE THROUGH THE FL STRAITS TONIGHT THROUGH WED...ACCOMPANIED BY SCATTERED SHOWERS AND SQUALLS...BEGINNING LATE THIS AFTERNOON. ALTHOUGH COMPUTER MODEL GUIDANCE DOES NOT SEEM TO CAPTURE THE ELY FLOW WELL THROUGH THE STRAITS...ELY FLOW NEAR 20 KT IS EXPECTED THERE BEGINNING EARLY WED...WITH SEAS BUILDING TO AROUND 5 FT. TROPICAL ATLC AND CARIBBEAN SEA... FRESH ELY TRADES WILL CONTINUE ACROSS THE BROADER CENTRAL CARIBBEAN WITH NE TO E WINDS AT 20 TO 25 KT...AND PERIODS OF SUSTAINED WINDS TO 30 KT ALONG THE COAST COLOMBIA THROUGH WED AFTERNOON. THE REMAINDER OF CARIBBEAN SEA TO THE S OF 20N IS EXPERIENCING MOSTLY 15 TO 20 KT WITH NE TO E WINDS AT 10 TO 15 KT OVER THE FAR NW WATERS. FAIR WEATHER AND THIS FRESH TRADE WIND FLOW WILL DOMINATE MUCH OF THE CARIBBEAN TODAY AND TONIGHT...AS SAHARAN AIR PREVAILS BETWEEN 13N AND 17N BETWEEN 70W AND 87W THIS MORNING. A TROPICAL WAVE OVER THE EASTERN CARIBBEAN HAS FRAGMENTED INTO TWO SECTIONS...WITH THE NORTHERN EXTENSION JUST CROSSING THE WINDWARD PASSAGE AND MOVING INTO THE SE BAHAMAS...AND WILL CONTINUE W-NW NEAR 20 KT TODAY BEFORE GRADUALLY SLOWING AS IS APPROACHES S FLORIDA LATE TONIGHT INTO WED. THE SOUTHERN PORTION OF THE TROPICAL WAVE WAS OVER THE EASTERN CARIBBEAN...WITH MAINLY SCATTERED SHOWERS AND A FEW TSTMS ALONG AND IN AN NARROW ZONE BEHIND IT. THIS WILL LIKELY CONTINUE TO BE THE TREND OF THIS WAVE...WEATHER WISE...AS IT MOVES W ACROSS THE CARIBBEAN AT NEAR 20 KT...REACHING ALONG 70W THIS EVENING...75W WED EVENING...AND 80W THU EVENING. A SECOND WAVE IN THE CENTRAL ATLC IS EXPECTED TO MOVE W AT NEAR 20 KT REACHING ALONG 55W THIS EVENING...ALONG 65W WED EVENING...AND TO 73W THU EVENING. A MILD RELAXATION IN WINDS AND SEAS WILL OCCUR AS THESE WAVES MOVES INTO THE W AND CENTRAL CARIB LATE WED-THU...AS THE LOW LEVEL FLOW WILL HAVE BECOME A BIT BACKED UP...UPSTREAM OF THESE WAVES. HOWEVER...A BROAD AND ELONGATED SURGE OF E-NE WINDS AT AROUND 20 KT WILL SPREAD FROM THE TROPICAL ATLC INTO THE ERN CARIB FRIDAY...AND BEGIN A TREND OF BUILDING WINDS AND SEAS W OF 50W THROUGH THE CARIB INTO THE WEEKEND....WITH THE POTENTIAL FOR GALE OR NEAR GALE FORCE WINDS OFF OF COLOMBIA...PER COHEN...AND SEAS BUILDING 10-12 FT PLUS IN THE W CENTRAL AND SW CARIB. SAHARAN AIR BEHIND THE LEADING EDGE OF THIS LLVL WIND SURGE COULD INDUCE VERY SQUALLY WEATHER ACROSS THE E AND NE CARIB THU AFTERNOON AND NIGHT. A THIRD WAVE IN THE EASTERN ATLC WILL REACH ALONG 55W FRI AND 62W SAT. SW ATLC W OF 55W... THE NORTHERN PORTION OF A TROPICAL WAVE HAS FRAGMENTED...AS AS DISCUSSED ABOVE...WAS MOVING THROUGH THE SE BAHAMAS THIS MORNING. SQUALLY WEATHER WILL MOVE THROUGH THE CENTRAL BAHAMAS AND TOWARDS THE FLORIDA STRAITS THIS MORNING...WITH SCATTERED SHOWERS AND A FEW TSTMS SPREADING W-NW ACROSS THE REST OF THE BAHAMA CHAIN IN THE NEXT 36 HOURS. A LOW LEVEL WIND SURGE ACCOMPANIES THIS FRAGMENTED TROPICAL WAVE...AND WILL INCREASE SURFACE WINDS TO AROUND 20 KT INTO THE BAHAMAS...WITH SEAS BUILDING TO 7 FT AS FAR AS ELEUTHERA BY THIS EVENING...ALLOWING SOME WIND SWELL TO SNEAK THROUGH THE PASSAGES AND RAISE SEA HEIGHTS INSIDE THE BAHAMAS AS WELL. OTHERWISE...A RIDGE AXIS EXTENDS ACROSS THE ATLC WATERS FROM BERMUDA TO N CENTRAL FL... AND IS EXPECTED TO CHANGE LITTLE TODAY THEN BEGIN TO SHIFT N REACHING ABOUT 29N THU AND FRI. GENERALLY EXPECTING S TO SW WINDS AT 10 TO 15 KT OVER THE NW WATERS...AND SE TO S OVER THE NE WATERS. E TO SE WINDS AT 10 TO 15 KT OVER THE AREA FROM 27N TO 23N. S OF 23N...EXPECT E WINDS AT 15 TO 20 KT...AND A SOLID 20 KT S OF 21-22N THROUGH WED NIGHT. WARNINGS ATLC... .NONE. CARIBBEAN... .NONE. GULF OF MEXICO... .NONE. $$ FORECASTER STRIPLING