000 AGXX40 KNHC 200708 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 308 AM EDT MON AUG 20 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... A NEARLY STATIONARY SURFACE TROUGH EXTENDS FROM NEAR TAMPA BAY FLORIDA TO 27N88W TO 25N95W. THIS FEATURE WAS PREVIOUS BEING CARRIED AS A SQUALL LINE AND SCATTERED SHOWERS AND ISOLATED TSTMS CONTINUE TO PULSE IN ITS VICINITY. A STATIONARY FRONT IS PARKED JUST INLAND OVER THE NW AND N CENTRAL GULF COAST U.S. STATES. THE FRONT AND TROUGH WILL CHANGE ORIENTATION AND PLACEMENT IN A MINOR FASHION THROUGH THE WEEK WITH THE FRONT EXPECTED TO VERY SLOWLY TRY AND PUSH E-SE AS A COLD FRONT BY THE END OF THE WEEK. ANOTHER SURFACE TROUGH IS IN THE FAR SW GULF OF MEXICO SPARKING SCATTERED SHOWERS AND TSTMS NEAR AND JUST OFFSHORE OF THE MEXICAN COAST. THIS FEATURE IS FORECAST TO LINGER THROUGH TUE. A TROPICAL WAVE WILL MOVE ACROSS THE YUCATAN PENINSULA TUE AND THEN ACROSS THE BAY OF CAMPECHE AND SW GULF WED...MERGING WITH THE SURFACE TROUGH THERE AS IT PUSHES INLAND INTO MAINLAND MEXICO BY LATE WED INTO THU. OTHERWISE A WEAK EXTENSION OF AN ATLC RIDGE WILL CONTINUE TO STRETCH FROM SW FLORIDA TO NEAR 24N89W THROUGH THE WEEK...LIFTING NORTHWARD THROUGH THE GULF THU AND FRI. LIGHT TO MODERATE WINDS WILL DOMINATE THE GULF OUTSIDE OF ANY CONVECTION THROUGH THE WEEK... WITH 1-3 FT SEAS IN THE NE GULF AND 2-4 FT...LOCALLY 4-5 FT ELSEWHERE. BY NEXT WEEKEND...AN AREA OF LOW PRES AND ATTENDANT TROPICAL WAVE MAY APPROACH THE SE GULF...ALTHOUGH THE EXACT TIMING AND STRENGTH OF THESE FEATURES IS UNCERTAIN. CARIBBEAN SEA AND TROPICAL N ATLC W OF 55W... A TROPICAL WAVE IS IN THE NW CARIBBEAN REACHING FROM NEAR THE CAYMAN ISLANDS TO JUST E OF THE COAST OF NICARAGUA. SCATTERED SHOWERS AND ISOLATED TSTMS CONTINUE TO PUSH W-NW MAINLY W OF THE WAVE AXIS. THE WAVE IS FORECAST TO MOVE ACROSS CENTRAL AMERICA AND THE YUCATAN PENINSULA TUE. FRESH TO STRONG WINDS ARE PRESENT IN THE CENTRAL CARIBBEAN AS MEASURED BY A RECENT ASCAT PASS WHERE THE PRES GRADIENT IS TIGHT BETWEEN ATLC RIDGING NE OF THE AREA AND LOW PRES ALONG PANAMA ASSOCIATED WITH THE MONSOON TROUGH. SEAS WILL BUILD TO UP TO 9 FT LATER TODAY NW OF THE COAST OF COLOMBIA AND THESE WINDS WILL REMAIN THROUGH EARLY WED WHILE STRETCHING IN COVERAGE IN BOTH THE E AND W DIRECTIONS. ALSO...WINDS WILL INCREASE TO 20-25 KT IN THE GULF OF HONDURAS MON NIGHT THROUGH WED AS THE MONSOON TROUGH LIFTS NORTHWARD CLOSER TO CENTRAL AMERICA. THE NEXT TROPICAL WAVE WILL ENTER THE TROPICAL N ATLC WATERS BY LATE MON NIGHT...THEN INTO THE E CARIBBEAN TUE AND QUICKLY TO THE CENTRAL CARIBBEAN WED. ATTENTION TURNS TOWARD THE FOLLOWING TROPICAL WAVE WHICH STEMS FROM 1010 MB LOW PRES NEAR 15N40.5W. MODEL GUIDANCE...ESPECIALLY THE GFS...CONTINUES TO TREND SOUTHWARD TAKING IT INTO THE E CARIBBEAN AND JUST S OF PUERTO RICO BY EARLY THU...THEN TO THE S OF HAITI BY EARLY FRI. THE GFS HAS ALSO TRENDED DOWNWARD INTENSITY-WISE WITH WINDS MAXING OUT AT 30-35 KT. THE 00 UTC ECMWF HAS A SLIGHTLY MORE SOUTHERLY TRACK COMPARED TO THE GFS WITH WINDS TOPPING OUT AT 25-30 KT AT BEST WITH A MUCH BROADER CIRCULATION MOVING ACROSS THE CENTRAL CARIBBEAN. MEANWHILE THE UKMET REMAINS MORE OF AN OUTLIER TAKING THE LOW ACROSS OR JUST NE OF THE NE CARIBBEAN ISLANDS AND N OR ACROSS PUERTO RICO BY EARLY FRI. NEEDLESS TO SAY THERE IS MUCH UNCERTAINTY WITH THIS LOW/TROPICAL WAVE. INTERESTS IN THE CARIBBEAN SHOULD CONTINUE TO MONITOR ANY DEVELOPMENTS OF THIS LOW THROUGH THE WEEK. A BLEND OF THE GFS AND ECMWF WERE USED FOR THIS PACKAGE ALONG WITH THE PRELIMINARY FORECAST FOR THIS LOW FROM THE HURRICANE SPECIALIST UNIT. SOUTHWEST NORTH ATLC S OF 31N W OF 55W... 1021 MB HIGH PRES IS CENTERED NEAR 27N61W WITH A RIDGE AXIS EXTENDING WESTWARD TO CENTRAL FLORIDA. A MID TO UPPER LEVEL TROUGH IS POSITIONED OVER THE U.S. TENNESSEE VALLEY AND PLENTIFUL MOISTURE AND UNSTABLE AIR CONTINUES TO BE PUMPED UP AHEAD OF THIS TROUGH ACROSS THE NW AND W PORTIONS OF THE SW N ATLC REGION. LATEST SCATTEROMETER AND IN-SITU OBSERVATIONS INDICATE LIGHT TO MODERATE WINDS ACROSS THE REGION...LOCALLY TO 20 KT S OF 22N AND ALSO IN THE NORTHERN PORTION OF AMZ111. THESE CONDITIONS WILL PERSIST TODAY...WITH CONDITIONS GOING DOWN HILL IN THE SE PORTION BEGINNING WITH AMZ125 AS THE HIGH/RIDGE SHIFT NORTHWARD WITH A TROPICAL WAVE AND ASSOCIATED WAVE APPROACHING FROM THE OPEN ATLC WATERS. THIS TROPICAL WAVE AND LOW ARE CURRENTLY FORECAST TO REMAIN JUST S OF THE AREA IN THE NE AND N CENTRAL CARIBBEAN BY THE MIDDLE TO END OF THE WEEK ALTHOUGH THERE WILL STILL BE FRESH TO AT LEAST STRONG WINDS ALONG WITH BUILDING EASTERLY SWELL MOVING ACROSS THE WATERS S OF 23N/24N WHERE A TIGHT PRES GRADIENT BETWEEN THE RIDGE AND LOW/WAVE WILL EXIST. THESE CONDITIONS WILL GRADUALLY SPREAD WESTWARD BY EARLY NEXT WEEKEND. 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