000 AGXX40 KNHC 180920 AAA MIMATS MARINE WEATHER DISCUSSION...UPDATED NWS NATIONAL HURRICANE CENTER MIAMI FL 520 AM EDT TUE OCT 18 2011 UPDATED GALE WINDS AHEAD AND BEHIND COLD FRONT IN SW N ATLC SECTION 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... A 1002 MB LOW CENTER JUST N OF THE YUCATAN PENINSULA NEAR 23N89W WITH A PRES OF 1002 MB IS PART OF AN AREA OF LOW THAT IS BECOMING ELONGATED NNE FROM S FLORIDA TO THE YUCATAN PENINSULA. A TIGHT PRES GRADIENT BETWEEN THE LOW PRES AREA AND HIGH PRES RIDGING TO THE NE IS CONTINUING TO MAINTAIN MINIMAL GALE FORCE WINDS TO THE NE AND E OF THE LOW FROM 23N TO 28N AND E TO NEAR 83W. BUOY 42003 AT 26N86W IS REPORTING SUSTAINED SE WINDS OF 31 KT WITH A PEAK WIND GUST OF 37 KT WITHIN THE PAST HOUR WITH A COMBINED SEA HEIGHT OF 10 FT. VERY DEEP CONVECTION TO THE E AND NE OF THE LOW IS APPROACHING THE SW FLORIDA COAST AS SEEN ON SATELLITE AND RADAR DATA. SEAS ARE IN THE RANGE OF 8-12 FT WITHIN THE GALE AREA TO THE NE AND E OF THE LOW. ELSEWHERE OVER THE E GULF ZONE WINDS ARE SE-S 20-25 KT WITH SEAS TO 8 FT. THE LOW IS FORECAST TO POSSIBLY REFORM FURTHER TO THE NE TODAY...AND MOVE QUICKLY NE TOWARDS W CENTRAL FLORIDA TONIGHT. GALE WINDS ARE EXPECTED TO DIMINISH TO JUST BELOW GALE FORCE BY EARLY THIS EVENING AS THE LOW NOW HAS A LOW PROBABILITY OF INTENSIFYING INTO A TROPICAL CYCLONE OVER THE NEXT 48 HRS. WINDS OVER THE REMAINDER OF THE GULF ARE E-SE 10-15 KT...EXCEPT S OF 28N BETWEEN 87W AND 91W WHERE N-NE WINDS OF 15-20 KT ARE NOTED PER BUOY AND ASCAT DATA. SEAS THERE...AND IN THE FAR NE GULF ARE 5-7 FT IN A NE SWELL. SEAS ELSEWHERE ARE 3-5 FT. THE NEXT MAJOR FEATURE TO AFFECT THE GULF WILL BE A STRONG COLD FRONT EXPECTED TO MOVE INTO THE FAR NW GULF EARLY THIS MORNING. THIS FRONT WILL QUICKLY MOVE SE REACHING FROM THE FLORIDA KEYS TO THE YUCATAN PENINSULA BY WED AFTERNOON ON THE HEALS OF THE DEPARTING LOW PRES SYSTEM. IT WILL THEN PUSH SE INTO THE WESTERN CARIBBEAN LATER ON WED. STRONG NORTHERLY WINDS WILL ARRIVE BEHIND THE FRONT WITH POSSIBLE GUSTS TO NEAR GALE FORCE OVER THE FAR NRN WATERS. NW-N GALE WINDS OF 25-35 KT ARE FORECAST TO BEGIN IN THE FAR SW GULF ZONE S OF 21N W OF 95W ON WED AS THE COLD AIR MASS FOLLOWING THE FRONT MOVES OVER THE WARM WATERS OF THE GULF AND INDUCES THE NECESSARY INSTABILITY TO RESULT THOSE WINDS. HIGH PRES WILL BUILD IN BEHIND THE FRONT LATE WED THROUGH SAT WITH WINDS GRADUALLY DIMINISHING FROM NW TO SE...DOWN TO 10-15 KT BY WED EVENING AS THE AIRMASS QUICKLY MODIFIES AND AS THE HIGH SINKS BACK DOWN OVER THE LOWER MISSISSIPPI VALLEY. ON THU WINDS BECOME E-SE IN DIRECTION IN THE FAR NW GULF ZONE...AND CONTINUE TO SAT AT SPEEDS OF 10-15 KT. CARIBBEAN SEA AND TROPICAL N ATLC... NOW THAT THE GULF OF MEXICO LOW HAS MOVED FARTHER AWAY FROM THE CARIBBEAN SEA...THE GRADIENT HAS RELAXED SOME IN THE FAR NW PORTION. BUOY 42056 AT 19.8N85W IS REPORTING S WINDS OF 20 KT WITH SEAS OF 6-7 FT. A JUST TO ITS SW HAS S-SW WINDS OF 20-25 KT. THE REMAINDER OF THE CARIBBEAN SEA IS UNDER MAINLY E WINDS OF 10-15 KT WINDS UNDER A RATHER WEAK PRES PATTERN. THE WINDS IN THE NW CARIBBEAN WILL SHIFT TO A MORE S-SW DIRECTION BY WED IN RESPONSE TO THE FIRST STRONG COLD FRONT OF THE SEASON TO MOVE INTO THE AREA. THE FRONT WILL PUSH INTO THE YUCATAN CHANNEL EARLY WED AFTERNOON...AND REACH FROM CENTRAL CUBA TO THE GULF OF HONDURAS WED EVENING...THEN FROM CENTRAL CUBA TO NE NICARAGUA BY THU EVENING. THE FRONT WILL BECOME STATIONARY FRI AND SAT WHILE WEAKENING FROM EASTERN CUBA TO NE NICARAGUA. A SURGE OF NORTHERLY 20-25 KT WINDS IS EXPECTED BEHIND THE FRONT WITH GUSTS TO 30 KT POSSIBLE IN AND NEAR THE YUCATAN CHANNEL. OTHERWISE...A WEAKENING TROPICAL WAVE IS OVER THE EASTERN CARIBBEAN SEA ALONG 67W/68W S OF 17N. SCATTERED SHOWERS AND ISOLATED TSTMS ARE NOTED E OF THE WAVE AXIS. THE WAVE WILL DAMPEN AND DISSIPATE OVER THE E CARIBBEAN THROUGH WED NIGHT. NE-E 15-20 KT WINDS AND SEAS TO 8 FT SHOULD CONTINUE THROUGH EARLY THU ACROSS THE MIDDLE TROPICAL N ATLC IN THE WAKE OF THE WAVE. ANOTHER TROPICAL WAVE WILL APPROACH THE TROPICAL N ATLC THU...AND THE LESSER ANTILLES EARLY FRI...AND INTO THE EASTERN CARIBBEAN SAT. SW N ATLC S OF 31N W OF 55W...UPDATED THE 0600 UTC SURFACE ANALYSIS SHOWS A HIGH PRES RIDGE ALONG 31N. TO THE S OF THE RIDGE LATEST SATELLITE IMAGERY AND NWS DOPPLER RADAR DISPLAYS SHOW ABUNDANT DEEP LAYER MOISTURE COVERING JUST ABOUT THE AREA RESULTING IN WIDESPREAD AREAS OF RAIN WITH EMBEDDED SHOWERS AND SCATTERED TSTMS. E-SE WINDS OF 15-20 KT ARE EVIDENT S OF 28N W OF 76W. ELSEWHERE BUOY REPORTS ALONG WITH A FEW SHIP OBSERVATIONS AND PARTIAL ASCAT DATA SHOW LIGHTER E WINDS OF GENERALLY 10-15 KT. SEAS ARE IN THE RANGE OF 3-5 FT...EXCEPT LOWER SEAS OF 2-3 FT IN THE VICINITY OF THE BAHAMAS AS WELL AS N OF 28N W OF 70W. THE RIDGE WILL WEAKEN AND RETREAT NE THROUGH TUE NIGHT IN RESPONSE TO THE GULF OF MEXICO LOW PRES SYSTEM ACCELERATING NORTHEASTWARD AND THE APPROACHING COLD FRONT. A STRONG PRES GRADIENT FORMS OVER THE NW WATERS E OF THE FRONT TODAY KICKING OFF SLY WINDS 20-30 KT...TO HIGHER RANGES IN THE GALE FORCE RANGE OF 30-40 KT BY TONIGHT WITH SEAS IN THE 8-14 FT RANGE. WINDS W OF THE FRONT WILL BECOME WNW 20-25 KT WITH SEAS OF 8-10 FT N OF 27N...AND NW-N 20 KT S OF 27N WITH SEAS UP 6 FT. THE COLD FRONT IS FORECAST TO EXTEND FROM NEAR 31N78W TO S FLORIDA BY WED AFTERNOON. LATEST ENSEMBLE 34 KT WIND PROBABILITIES SHOW 20-40 PERCENT FOR GALE PROBABILITIES FOR TONIGHT INTO WED MORNING E OF THE FRONT TO 74W AND N OF 28N. BY WED AFTERNOON THE SLY GALE WINDS ARE FORECAST TO DIMINISH TO 25-30 KT. THE FRONT WILL THEN REACH FROM 31N74W TO CENTRAL CUBA BY EARLY THU AS IT BEGINS TO WEAKEN AND SLOW DOWN. BY FRI IT SHOULD TRANSITION TO A STATIONARY FRONT FROM NEAR 31N7OW TO CENTRAL CUBA...AND REMAIN ALONG THAT POSITION THROUGH SAT. W-NW 20-25 KT WINDS ARE EXPECTED BEHIND THE FRONT WED...EXCEPT TO THE N OF 27N CLOSER TO THE COAST WINDS COULD REACH UP TO 30 KT WITH SOME GUSTS TO NEAR GALE FORCE. WINDS THEN QUICKLY DIMINISH TO 10-15 KT THU AND FRI...AND SHIFT TO THE N-NE OVER THE SW PORTION AS HIGH PRES BUILDS IN FROM THE WNW BEHIND THE WEAKENING FRONT. A TIGHTER PRES GRADIENT IN THE SW PORTION SHOULD ALLOW FOR HIGHER N-NE 20 KT WINDS TO EXIST S OF 26N THU THROUGH SAT. ELSEWHERE WINDS WILL BE GENERALLY E 10-15 KT THU THROUGH SAT WITH SEAS IN THE RANGE OF 3-5 FT...EXCEPT 2-3 FT IN THE NW PORTION. WARNINGS... GULF OF MEXICO... .GMZ084 AND GMZ086...GALE WARNING FROM 22N TO 28N BETWEEN 83W AND 85W... .GMZ082...GALE CONDITIONS EXPECTED S OF 21N W OF 95W EARLY WED... .CARIBBEAN SEA AND TROPICAL N ATLC... .NONE. SW N ATLC... .AMZ080...GALE WARNING N OF 28N BETWEEN 74W AND COLD FRONT... FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ FORECASTER AGUIRRE