000 AGXX40 KNHC 180641 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 241 AM EDT SAT AUG 18 2012 MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO...CARIBBEAN SEA AND TROPICAL N ATLC...AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. GULF OF MEXICO... MINIMAL TROPICAL STORM HELENE AT 18/0600 UTC IS NEAR THE GULF COAST OF MEXICO NEAR 21.2N 96.W OR ABOUT 65 MILES ENE OF TUXPAN MEXICO...120 MILES SE OF TAMPICO MEXICO MOVING NW AROUND 5 KT. MAXIMUM SUSTAINED WINDS ARE 35 KT WITH GUSTS TO 45 KT AND THE ESTIMATED MINIMUM CENTRAL PRES WAS 1006 MB. ASSOCIATED CONVECTION HAS RAPIDLY DIMINISHED DURING THE PAST SEVERAL HOURS WITH ONLY SCATTERED SHOWERS AND TSTMS OCCURRING MAINLY WITHIN 120 NM OF THE CENTER OF HELENE. REGARDLESS...LOCALLY HEAVY RAINFALL IS STILL POSSIBLE DURING THE NEXT FEW DAYS OVER MEXICO WITH UP TO 15 INCHES RESULTING IN LIFE-THREATENING FLASH FLOODS AND MUDSLIDES AT HIGHER ELEVATIONS. HELENE IS FORECAST TO MAKE LANDFALL LATER TODAY THEN WILL DISSIPATE OVER THE HIGH TERRAIN OF EASTERN MEXICO. MEANWHILE A TROUGH IS OVER THE WESTERN YUCATAN PENINSULA AND THIS TROUGH IS LIKELY THE REMNANTS OF A TROPICAL WAVE THAT HAD BEEN MOVING THROUGH THE CARIBBEAN A FEW DAYS AGO. SCATTERED TO NUMEROUS SHOWERS AND TSTMS ARE OCCURRING W OF THE WAVE IN THE BAY OF CAMPECHE. THIS FEATURE WILL SHIFT W ACROSS THE SW GULF OF MEXICO THROUGH SUN. OTHERWISE...WEAK 1016 MB HIGH PRES IS POSITIONED IN THE CENTRAL GULF WITH LIGHT TO MODERATE WINDS AND 1-3 FT SEAS PRESENT OUTSIDE OF HELENE AND THE TROUGH. THESE CONDITIONS ARE EXPECTED TO PERSIST THROUGH THE WEEKEND. THEREAFTER THE LATEST RUN OF THE GFS DISSIPATES THE HIGH AS A COLD FRONT MOVES INTO THE NW GULF EARLY MON...SLOWLY SHIFTING EASTWARD ACROSS THE NORTHERN GULF WATERS THROUGH MIDWEEK. THE ECMWF ALSO SHOWS THIS FRONT WITH IT BECOMING STALLED OUT IN THE N CENTRAL GULF BY WED. A BLEND OF THE GFS AND ECMWF WAS USED FOR THE GULF ALONG WITH THE WAVEWATCH MODEL FOR SEAS...ALTHOUGH SEAS WERE BUMPED UP 1-3 FT NEAR HELENE PRIOR TO LANDFALL. CARIBBEAN SEA AND TROPICAL N ATLC W OF 55W... A TROPICAL WAVE IS IN THE E CARIBBEAN EXTENDING FROM WESTERN PUERTO RICO TO NEAR 23N67W. SCATTERED SHOWERS AND TSTMS ACCOMPANY IT AS INDICATED BY WSR-88D RADAR FROM SAN JUAN...ALONG WITH GUSTY WINDS AND SQUALLY CONDITIONS. FRESH TO STRONG NE-E WINDS CONTINUE NEAR THE COAST OF COLOMBIA AS VERIFIED BY A RECENT ASCAT PASS. 15-20 WINDS ARE PRESENT IN THE GULF OF HONDURAS AS MEASURED BY THE SAME ASCAT PASS WHERE THE PRES GRADIENT IS PINCHED BETWEEN A TROUGH TO THE W OVER THE YUCATAN AND A RIDGE NE OF THE AREA. OTHERWISE LIGHT TO MODERATE WINDS ARE ACROSS THE REMAINDER OF THE CARIBBEAN. NO MAJOR CHANGES ARE ANTICIPATED THROUGH EARLY MON...ALTHOUGH WINDS WILL INCREASE TO 20-25 KT ACROSS THE CENTRAL CARIBBEAN WATERS BY LATE MON THROUGH EARLY WED IN THE WAKE OF THE TROPICAL WAVE AS HIGH PRES STRENGTHENS NE OF THE AREA. E-SE 20-25 KT WINDS WILL ALSO SET UP OVER THE GULF OF HONDURAS TUE AND WED WITH THE REBUILDING HIGH/RIDGE NE OF THE AREA...AND LOWER PRES OVER THE YUCATAN AND SW GULF OF MEXICO NW OF THAT AREA. THE NEXT TROPICAL WAVE WILL IMPACT THE TROPICAL N ATLC WATERS LATE SUN INTO MON...MOVING THROUGH THE E CARIBBEAN TUE AND WED WITH LITTLE FANFARE. ALL EYES WILL BE ON THE FOLLOWING WAVE CURRENTLY OVER THE CAPE VERDE ISLANDS WITH ATTENDANT LOW PRES NEAR 12N27W AT 0600 UTC. ALL GLOBAL MODEL GUIDANCE...ESPECIALLY THE GFS...RAPIDLY DEVELOPS AND INTENSIFIES THIS LOW AS IT MOVES W-NW WITH ASSOCIATED CONDITIONS IMPACTING THE TROPICAL N ATLC BEGINNING LATE TUE THROUGH THU. THIS LOW/TROPICAL WAVE HAS A MEDIUM CHANCE OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS AND INTERESTS IN THE E CARIBBEAN ISLANDS SHOULD CONTINUE TO MONITOR ITS PROGRESS DURING THE NEXT SEVERAL DAYS. A BLEND OF THE GFS AND ECMWF WAS USED THROUGHOUT THE NEXT 5 DAYS...WITH WINDS CAPPED AT 30 KT AND SEAS AT 14 FT...FOR NOW. SOUTHWEST NORTH ATLC S OF 31N W OF 55W... 1022 MB HIGH PRES IS POSITIONED NEAR 27N55W WITH A RIDGE REACHING WESTWARD TO NEAR 27N75W. A TROUGH IS SCRAPPING ACROSS THE WATERS N OF 27N STRETCHING FROM NEAR 31N78W TO 27N80W. SCATTERED SHOWERS AND TSTMS PRECEDE THE TROUGH WITH UNSTABLE CONDITIONS REACHING ALL THE WAY TO 70W. THIS TROUGH WILL LIFT NE OF THE AREA TODAY INTO TONIGHT AS THE HIGH CENTER SHIFTS WESTWARD. THE HIGH WILL DOMINATE THE CONDITIONS ACROSS THE SW N ATLANTIC WATERS THROUGH THE WEEKEND INTO NEXT WEEK WITH MAINLY LIGHT TO MODERATE WINDS AND 2-4 FT SEAS ACROSS THE MAJORITY OF THE REGION. THE EXCEPTIONS WILL BE WINDS OCCASIONALLY UP TO 15-20 KT AND SEAS TO 5 FT S OF 22N N OF THE GREATER ANTILLES... AS WELL AS E OF NORTHERN FLORIDA AS SEVERAL TROUGHS SKIRT BY N OF 31N. ALSO...SEAS WILL BE 1-3 FT W OF THE BAHAMAS. AS MENTIONED IN THE CARIBBEAN/TROPICAL N ATLC SECTION ABOVE...A LOW/TROPICAL WAVE IS FORECAST TO IMPACT THE WATERS S OF 22N E OF 60W WED INTO THU. 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 LEWITSKY