000 AGXX40 KNHC 220758 RRA MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 350 AM EDT SUN APR 22 2012 MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. GULF OF MEXICO... A VIGOROUS DEEP LAYER TROUGH EXTENDS FROM THE UPPER OHIO VALLEY REGION S TO THE NE GULF WHERE A LARGE VORT MAX ON THE SRN TIER OF THE TROUGH MOVING ENE IS LOCATED AT 28N85W. THIS FEATURE SUPPORTS A 1001 MB SURFACE LOW ALSO AT 28N85W. A COLD FRONT EXTENDS FROM THE LOW S TO 25N91W AND SW TO INLAND THE NE YUCATAN PENINSULA MOVING SE AT 25 KT. A POST-FRONTAL TROUGH EXTENDS FROM THE LOW SW TO 26N89W TO 24N95W. A WEAK 1018 MB HIGH IS OVER THE FAR SW BAY OF CAMPECHE NEAR 22N97W. LATEST N CENTRAL GULF BUOYS SHOW N WINDS OF 25-30 KT W OF THE LOW AND TO THE N OF THE TROUGH WHERE THE PRES GRADIENT HAS TIGHTENED DURING THE LAST SEVERAL HOURS. AN ASCAT PASS FROM NEAR 0230 UTC LAST NIGHT REVEALED SIMILAR WINDS. SEAS THERE ARE IN THE RANGE OF 5-7 FT. THE SAME ASCAT PASS SHOWED W-NW WINDS OF 20-25 KT BEHIND THE FRONT TO NEAR 90W...AND SLY WINDS OF 20 KT E OF THE FRONT FROM 24N TO 28N...WITH S-SW 25-20 KT WINDS S OF 24N SE OF THE FRONT. E AND CENTRAL GULF BUOYS ARE REPORTING SIMILAR CONDITIONS. SEAS HAVE BUILD QUICKLY TO 7-10 FT ELSEWHERE BEHIND THE FRONT TO 94W...AND 6-8 FT E OF THE FRONT S OF 28N. SEAS ARE 5-6 FT N OF 28N E OF THE FRONT AND LOW. BOTH SATELLITE AND RADAR DATA FROM LAST NIGHT AND EARLY THIS MORNING REVEAL NUMEROUS STRONG TSTMS ACROSS THE CENTRAL GULF AND WRN GULF PORTIONS N OF 23N BETWEEN THE COLD FRONT AND 89W...AND E OF THE SURFACE TROUGH FROM 23N TO 28N. AS FOR THE FORECAST...NWP MODELS ARE IN PRETTY GOOD AGREEMENT IN FORECAST THE LOW TO ACCELERATE NE AND INTENSITY DRAGGING THE COLD ACROSS THE REMAINDER OF THE GULF DURING TODAY...AND TO E OF THE AREA BY EARLY TONIGHT. THE POST-FRONTAL TROUGH WILL REACH CENTRAL FLORIDA EARLY TONIGHT...AND TO JUST SE OF THE GULF BY EARLY MON NIGHT. NLY WINDS IN THE WAKE OF THE FRONT WILL GRADUALLY DIMINISH THROUGH EARLY TUE AS WEAK HIGH PRES IN THE WRN GULF BEGINS TO MAKE IT MOVE EWD. THIS HIGH CENTER WILL REMAIN NEARLY STATIONARY THROUGH MON NIGHT...SHIFT EWD TO THE CENTRAL PORTION BY LATE TUE NIGHT...AND TO THE ERN PORTION WED THEN TO OVER CENTRAL FLORIDA THU. THIS WILL ALSO ALLOW FOR SE RETURN FLOW TO SET UP IN THE FAR WRN WHILE ALSO INCREASE IN SPEED DUE TO THE TIGHTENING PRES GRADIENT BETWEEN THE HIGH AND DEEPENING LOW PRES IN THE SRN PLAINS. SEAS BUILD TO 7-8 FT IN THE FAR WRN GULF WATERS WED AND THU. SW NORTH ATLC S OF 31N W OF 65W... A WEAK RIDGE OVER THE NE PORTION CONTINUES TO SHIFT NEWD IN RESPONSE TO THE APPROACHING LOW PRES SYSTEM CURRENTLY W OF THE AREA IN THE ERN GULF OF MEXICO. THE PRES GRADIENT IN THE WRN PORTION HAS ALREADY RESPONDED TO THE BOTH OF THESE FEATURES BY TIGHTENING QUITE DRAMATICALLY AS EVIDENT IN THE BROAD AREA OF INCREASING SLY WINDS OBSERVED TO THE W OF 70W. THESE WINDS RANGE IN SPEEDS OF 20-25 KT WITH GUSTS TO 30 KT AS REVEALED BY THE BUOYS THERE. THESE WINDS WILL INCREASE SOME MORE TO 20-30 KT WHILE SPREADING EWD THROUGH TONIGHT IN ADVANCE OF THE APPROACHING GULF OF MEXICO FRONTAL SYSTEM. STILL CAN'T RULE OUT BRIEF GUSTS TO GALE FORCE TODAY WITH THESE WINDS. GRIDDED WIND GUST GUIDANCE SUGGESTS THIS IS POSSIBLE AS NUMEROUS SHOWERS AND TSTMS QUICKLY SPREAD EWD FROM CENTRAL CUBA NE TO ZONE 113...AND WHILE SIMILAR CONVECTIVE ACTIVITY ENTERS THE FAR W AND NW WATERS. SEAS IN THE NRN PORTION OF THE WRN ATLC ARE FORECAST TO BUILD UP TO 12 OR 13 FT TODAY AND TONIGHT...AND SPREAD ENE THROUGH MON AS PER CONSENSUS OF GUIDANCE FROM THE VARIOUS WAVEWATCH MODELS. A GALE WARNING FOR SLY WINDS IS ALREADY IN EFFECT FOR THE WATERS JUST N OF THE AREA DUE TO THE APPROACHING LOW PRES SYSTEM. THE RATHER STRONG COLD FRONT ASSOCIATED WITH THIS SYSTEM IS SCHEDULED TO ENTER THE FAR NW WATERS THIS MORNING AS THE ATTENDANT LOW TRACKS NE ACROSS THE FLORIDA BIG BEND AREA BEFORE DAYBREAK...AND FURTHER NE TO ALONG THE SE U.S. COAST WHILE DEEPENING THROUGH LATE THIS AFTERNOON AND EVENING. BASED ON GENERAL NWP MODEL CONSENSUS...THE COLD FRONT WILL REACH FROM NEAR 31N78W TO WRN CUBA BY EARLY TONIGHT...FROM NEAR 31N74W TO CENTRAL CUBA BY EARLY MON MORNING...FROM NEAR 31N70W TO NEAR WINDWARD PASSAGE EARLY MON EVENING...THEN BEGIN TO WEAKEN AS IT REACHES A POSITION FROM NEAR 31N68W TO 24N71W THEN WEAKENING NEAR NW HAITI/WINDWARD PASSAGE BY EARLY TUE MORNING...FROM 25N65W TO THE DOMINICAN REPUBLIC BY EARLY WED MORNING...AND WEAKEN FURTHER TO A FRONTAL TROUGH OVER THE FAR SE WATERS LATE WED AND THU THAT BEGINS TO SHIFT WWD. WINDS AND SEAS DIMINISH OVER THE AREA BEHIND THE FRONT AS HIGH PRES BUILDS OVER THE CENTRAL PORTION OF THE FORECAST ATLC WATERS THROUGH WED...THEN SHIFTS ENE INTO THU. THE PRES GRADIENT TIGHTENS OVER MUCH OF THE SRN WATERS LATE WED AND THU WHERE NE-E 20 KT ARE FORECASTED BY THE GLOBAL MODELS. CARIBBEAN SEA... BUOY OBSERVATIONS FROM THROUGHOUT THE BASIN ARE REPORTING E TO SE WNDS OF 10-15 KT THROUGHOUT...EXCEPT IN THE NW CARIBBEAN WHERE SLY WINDS OF 20 KT WERE EVIDENT BOTH IN ASCAT AND OSCAT DATA FROM LAST NIGHT. THIS IS DUE TO THE APPROACHING GULF OF MEXICO COLD FRONT. MAX SEAS HAVE LOWERED TO 3-5 FT OVER MOST OF THE AREA... EXCEPT 2-3 FT IN THE FAR NRN PORTIONS E OF 80W. HIGH PRES N OF THE AREA WILL SHIFT NE THROUGH MON ALLOWING FOR THE SRN PORTION OF THE COLD FRONT JUST NW OF THE YUCATAN CHANNEL TO PUSH SE THROUGH THE CHANNEL BEFORE DAYBREAK TODAY...FROM NW CUBA TO NEAR 18N86W LATER THIS MORNING...FROM WRN CUBA TO NEAR 18N86W EARLY THIS AFTERNOON...FROM W/CENTRAL CUBA TO GULF OF HONDURAS EARLY THIS EVENING...THEN BEGIN TO WEAKEN AND SLOW DOWN AS IT REACHES FROM ERN CUBA TO NE HONDURAS EARLY MON AFTERNOON...FROM VICINITY WINDWARD PASSAGE TO NICARAGUA AS A CONTINUED WEAKENING FRONT EARLY MON NIGHT...FROM NEAR WRN HAITI/WINDWARD PASSAGE TO NEAR 15N79W EARLY ON TUE...THEN BECOME STATIONARY AS A TROUGH OVER THE N CENTRAL WATERS FROM HISPANIOLA S TO NEAR 15N74W WED. THE TROUGH WILL THEN BEGIN TO MOVE BACK W TO THE VICINITY OF THE WINDWARD PASSAGE INTO THU. THE FRONT WILL BE FOLLOWED BY NW WINDS OF 20 KT...THAT THEN DIMINISH TO 10-15 KT LATE MON AS HIGH PRES BUILDS IN BEHIND THE FRONT. HOWEVER...THE DIMINISHED WINDS WILL BE SHORT-LIVED AS THE PRES GRADIENT IS DUE TO TIGHTEN AGAIN OVER THE NRN CARIBBEAN WATERS LATE TUE THROUGH THU DUE TO ATLC HIGH PRES THAT BUILDS EWD AND INTERACTS WITH THE REMNANTS OF THE FRONT NEAR HISPANIOLA AND THE WINDWARD PASSAGE AND WITH GENERALLY LOWER PRES OVER THE CENTRAL AND SRN CARIBBEAN SEA. TROPICAL N ATLC S OF 19N W OF 55W... LIGHT NE-E WINDS PREVAIL THROUGHOUT...EXCEPT IN THE FAR SRN PORTION WHERE SLIGHTER STRONGER NE WINDS OF 15-20 KT WERE REVEALED IN THE 0044 UTC ASCAT PASS FROM LAST NIGHT. ALSO ...SHIP "KAQP" JUST E OF THE ZONE AT 7.5N53W REPORTED E WINDS OF 20 KT NOT TOO LONG AGO. SEAS ARE IN THE RANGE OF 4-5 FT. LIKE MENTIONED IN PREVIOUS FORECASTS...LITTLE OVERALL CHANGE IS EXPECTED WITH THE CURRENT CONDITIONS THROUGHOUT THIS FORECAST PERIOD. THE COLD FRONT FEATURE DESCRIBED IN ABOVE SECTIONS SHOULD HAVE LITTLE IMPACT ON THIS PORTION OF THE ATLC AS IT APPROACHES THE FAR NW WATERS AS A FRONTAL TROUGH ON WED BEFORE MOVING BACK W. NOTE... EFFECTIVE APR 3, 2012 AT 1800 UTC THE OFFSHORE WATERS FORECAST ZONES CHANGED FOR THE CARIBBEAN AND SW N ATLANTIC AND THE GULF OF MEXICO. ISSUANCE TIME FOR THE GULF OF MEXICO OFFSHORE WATERS FORECASTS IS REFERENCED TO THE EASTERN TIME ZONE. FOR DETAILS SEE WWW.NHC.NOAA.GOV/ABOUTTAFBPROD.SHTML#OWF GRIDDED MARINE OUTPUT IS AVAILABLE AT WWW.NHC.NOAA.GOV/TAFB/GRIDDED_MARINE (LOWER CASE). GULF OF MEXICO... .NONE. .CARIBBEAN SEA AND TROPICAL N ATLC... .NONE. .SW N ATLC... .NONE. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ FORECASTER AGUIRRE