000 AGXX40 KNHC 300909 AAA MIMATS MARINE WEATHER DISCUSSION...UPDATED NWS NATIONAL HURRICANE CENTER MIAMI FL 510 AM EDT TUE AUG 30 2011 UPDATED CARIBBEAN AND TROPICAL N ATLC...AND WARNINGS SECTION TO INCLUDE FORECAST AND WARNING INFORMATION ON RECENTLY UPGRADED TROPICAL STORM KATIA 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... RECENT AND CURRENT BUOY OBSERVATIONS SHOW S-SW WIND FLOW OVER THE EASTERN GULF ZONE...WITH SPEEDS OF 5-10 KT. OVER THE REMAINDER OF THE GULF WINDS GENERALLY NE-E AT 5-10 KT...EXCEPT IN THE FAR WESTERN NW GULF WHERE WINDS HAVE VEERED TO THE SE AT 10 KT AND OVER THE FAR SOUTHERN MIDDLE GULF ZONE WHERE WINDS ARE SE 10-15 KT. OBSERVED SEAS THROUGHOUT ARE IN THE 1-2 FT...WITH THE EXCEPTION OF THE FAR SOUTHERN MIDDLE GULF WHERE THEY ARE 2-3 FT. THE PRELIMINARY 0600 UTC SURFACE ANALYSIS REVEALS A DISSIPATING STATIONARY FRONT THAT EXTENDS FROM APALACHEE BAY SW TO NEAR 27N88W...OTHERWISE A RATHER WEAK PRES PATTERN PREVAILS. THE FRONT WILL DISSIPATE LATE TODAY AS HIGH PRES BUILDS WESTWARD TO THE N OF THE AREA THROUGH THU...THEN LIFTS TO THE NE FRI AND SAT. AS A RESULT...WINDS WILL EVENTUALLY BECOME E-SE 10-15 KT ACROSS THE AREA THROUGH THE END OF WEEK. UNCERTAINTY LEADS INTO THE FORECASTER BEGINNING AROUND THU THROUGH SAT AS MODELS CONTINUE TO SUGGEST...AS IN PREVIOUS DAYS...THAT LOW PRES DEVELOPS OVER THE SW GULF ZONE LATER THIS WEEK. CURRENTLY WATER VAPOR IMAGERY SHOWS AN UPPER LEVEL TROUGH STRETCH FROM NE TO SW FROM THE FLORIDA PANHANDLE SW TO A DEVELOPING UPPER LOW NEAR JUST INLAND THE MEXICAN COAST NEAR 23N98W. THIS FEATURE SHOULD HELP INITIATE THE INCIPIENT SURFACE TROUGH OVER THE SW GULF THAT SHOULD LEAD TO THE EVOLUTION OF THE LOW. MODEL DIFFERENCES LIE WITH RESPECT TO MAINLY THE TRACK OF THIS LOW FEATURE. MODELS...WITH THE EXCEPTION OF THE GFS AND REGIONAL NAM...LIKE TO TRACK THE LOW IN A GENERAL NW DIRECTION TOWARDS THE VICINITY OF NE MEXICO. THE GFS AND NAM DEPICT A MUCH DEEPER LOW...AND MOVE IT IN A NORTHWARD DIRECTION ACROSS THE NW GULF ZONE FRI AND SAT...WHILE THE ECMWF IS MORE OF A COMPROMISE BETWEEN THE MODELS IN TAKING THE LOW TO THE SOUTHERN BOUNDARY OF THE NW GULF BY SAT. THE MAIN ISSUE WITH THIS FEATURE NO MATTER WHAT PATH IT TAKES IN ITS TRACK THROUGH THE WESTERN GULF ONCE IF FORMS LATER THIS WEEK...WILL BE A TIGHTENING PRES GRADIENT EXPECTED TO DEVELOP OVER MUCH OF MIDDLE AND WESTERN GULF FRI AND SAT BETWEEN THE LOW AND THE HIGH PRES TO ITS NE RESULTING IN POSSIBLE E-SE WINDS OF 20-25 KT...AND SE-S 15-20 KT IN THE EASTERN PORTION OF THE SW GULF. THE TIGHT FETCH CREATED BY THE TIGHTENING GRADIENT SHOULD RESULT IN BUILDING SEAS AS HIGH AS PERHAPS 7 OR 8 FT BY SAT. LATEST NOAA WAVEWATCH GUIDANCE LOOKS REASONABLE WITH INITIAL SEA STATE VALUES...AND WILL BE USED FOR THROUGH EARLY THU. THEN AFTER THAT WILL MOSTLY ADJUST SEA HEIGHTS SUBSTANTIALLY UPWARDS ...PERHAPS FOLLOWING THE ECMWF WAVE GUIDANCE TO ACCOUNT FOR THE BUILDING SEAS UNDER THE TIGHT PRES GRADIENT ASSOCIATED WITH THE LOW. SW ATLC S OF 31N W OF 55W... S-SW WINDS ALONG WITH HAVE CONTINUED TO DECREASE N OF 27N AS NOTED BUOY DATA...AND FURTHER SUPPORTED BY AN ASCAT PASS FROM JUST PAST 0200 UTC LAST NIGHT. WINDS THERE ARE S-SW 10 KT...AND SEAS ARE IN THE 3-5 FT N OF 27N E OF 76W...AND 2-4 FT W OF 76W. ELSEWHERE WINDS ARE SE-S 10-15 KT E OF THE BAHAMAS ...EXCEPT E-SE 10-15 KT S OF 24N...AND SE-S 10-15 KT ELSEWHERE. SEAS ELSEWHERE ARE 3-5 FT E OF THE BAHAMAS...AND 2-3 FT W OF BAHAMAS. SEAS E OF THE BAHAMAS ARE FORECAST TO SUBSIDE TO 2-3 FT...AND CONDITIONS THROUGHOUT SHOULD VARY VERY LITTLE THROUGH THE PERIOD. THE PRELIMINARY 0600 UTC ANALYSIS SHOWS A WEAK RIDGE STRETCHING FROM 27N65W TO S FLORIDA...AND THIS REMAINS THE MAIN FEATURE ACROSS THE AREA. THE RIDGE WILL LIFT NWD TODAY AND TONIGHT... THEN WEAKEN AND RETREAT EASTWARD WED AND THU AS A WEAK COLD FRONT ENTERS INTO THE NW PORTION. THE FRONT WILL MOVE SLOWLY E ACROSS THE NORTHERN WATERS WED THROUGH SAT WITH A WEAK PRES PATTERN SETTING UP OVER THE AREA. A NARROW SWATH OF 15-20 KT E WINDS WILL EXIST BETWEEN THE SE BAHAMAS THROUGH AT LEAST WED NIGHT. CARIBBEAN SEA AND TROPICAL N ATLC S OF 22N W OF 55W... ASCAT DATA FROM 0200 UTC LAST NIGHT ALONG WITH RECENT AND CURRENT BUOY OBSERVATIONS REVEAL LIGHT E WINDS THROUGHOUT...EXCEPT IN THE CARIBBEAN PORTION FROM 11N-18N BETWEEN 68W-76W WHERE WINDS ARE NE-E 15-20 KT...AND OVER THE EASTERN PART OF THE NW CARIBBEAN WHERE WINDS ARE SE-S 15-20 KT. WINDS ARE NE-E 10 KT IN THE TROPICAL N ATLC ZONE. UPCOMING CHANGES TO AREA WINDS WILL BE SEEN AS AN EXPANSION OF THE 15-20 KT CARIBBEAN WINDS NORTHWESTWARD THROUGH MOST OF THU AS THE GRADIENT BETWEEN THE ATLC RIDGE AND LOWER PRES OVER THE SOUTHERN CARIBBEAN SEAS W OF 70W INCREASES. LATER ON THU AND INTO SAT THE GRADIENT WEAKENS WITH THE RIDGE N OF THE AREA RETREATING EASTWARD ALLOWING FOR THE E-SE WINDS TO DIMINISH TO MOSTLY 10-15 KT...EXCEPT IN THE FAR SOUTHERN SECTION OF THE EASTERN CARIBBEAN AND NEAR THE NE COAST OF HONDURAS WHERE WINDS SHOULD REMAIN AT 20 KT SPEEDS. EXPECT SEAS UP TO 9 FT IN THE SW CARIBBEAN N OF 12N BETWEEN 75W-80W AND NEAR THE COAST OF COLOMBIA THROUGH WED NIGHT BEFORE SUBSIDING TO 7 FT THU...AND TO 2-4 FT BY SAT. NEWLY UPGRADED TROPICAL STORM KATIA IN THE FAR EASTERN ATLANTIC IS FORECAST TO APPROACH TO THE TROPICAL N ATLC BY LATE FRI...AND TRACK NW ACROSS THE NORTHERN PORTION OF THE ZONE THROUGH SAT. PLEASE SEE THE LATEST INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADER MIATCPAT2/WTNT32 KNHC AND THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADER MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS ON TROPICAL STORM KATIA. WARNINGS...UPDATED GULF OF MEXICO... .NONE. CARIBBEAN... .NONE. TROPICAL N ATLC... .AMZ087...HURRICANE CONDITIONS EXPECTED N OF 15N E OF 60W SAT... SW N ATLC... .NONE. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ FORECASTER AGUIRRE