000 AGXX40 KNHC 131903 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 300 PM EDT MON AUG 13 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... THE WESTERN EXTENSION OF ATLC HIGH PRES RIDGING PROTRUDES ACROSS THE GULF ALONG 26N...AND IS THE DOMINANT FEATURE OVER THE THE REGION. A STATIONARY FRONT EXTENDS FROM SE GEORGIA SW TO ALONG THE FLORIDA PANHANDLE COAST AND NW TO NEAR MOBILE BAY. A RATHER DEEP LAYER TROUGH FOR THIS TIME OF YEAR IS RAPIDLY PROGRESSING EASTWARD ACROSS THE SE UNITED STATES. A VERY MOIST AND UNSTABLE AIR MASS AHEAD OF THE TROUGH IS PRESENTLY SUPPORTING ISOLATED SHOWERS AND TSTMS OVER MUCH OF THE NRN AND CENTRAL GULF ZONES. RATHER ACTIVE CONVECTION IN THE FORM OF SCATTERED MODERATE TO ISOLATED STRONG TSTM ACTIVITY IS IDENTIFIED IN THE SW PART OF THE GULF S OF ABOUT 24N AND W OF 93W. GUSTY WINDS ARE POSSIBLE WITH THIS ACTIVITY AS IT IS EXPECTED TO LAST INTO AT LEAST TUE UNDER AN UPPER LEVEL RIDGE THAT EXTENDS FROM THE NE PACIFIC NE TO THE SW GULF. CURRENT BUOY AND OIL PLATFORM OBSERVATIONS SHOW RELATIVELY LIGHT WINDS THROUGHOUT. SE-S WINDS OF 10-15 KT ARE S OF THE RIDGE EXCEPT SW IN DIRECTION IN THE FAR WRN PORTION NEAR THE TEXAS COAST. SW WINDS OF 5-10 KT ARE N OF THE RIDGE W OF 88W...EXCEPT VARIABLE 5 KT IN THE FAR NE PORTION. THE BUOYS SHOW SEAS IN THE 1-2 FT RANGE EXCEPT 3-4 FT IN THE SW PART OF THE GULF WITH THE OCCASIONAL SEAS TO 5 FT. LATEST MODEL RUNS ARE IN GENERAL GOOD AGREEMENT THAT THE RIDGE WILL SHIFT N TO ALONG 27N TUE...AND FURTHER N TO ALONG 28N WED AND THU AND TO NEAR 29/30N FRI AND SAT. WEAK FRONTAL BOUNDARIES SHOULD REMAIN N OF THE FORECAST WATERS THROUGH THE PERIOD...WITH RELATED TSTM ACTIVITY REACHING THE FAR NRN FRINGES OF THE WATERS. THE NOAA WAVEWATCH III GUIDANCE AGAIN LOOKS REASONABLE WITH SEAS BEING OBSERVED THROUGHOUT THE GULF. WILL USE THE LATEST GUIDANCE FOR THIS FORECAST. SW N ATLC S OF 31N W OF 65W... THE PRELIMINARY 18 UTC SURFACE ANALYSIS DEPICTS THE MAIN FEATURE BEING A RIDGE THAT EXTENDS FROM BERMUDA SW TO S CENTRAL FLORIDA AND CONTINUES W TO THE GULF. LATEST BUOY OBSERVATIONS ALONG WITH A FEW SHIP REPORTS REVEAL SE WINDS OF 10-15 KT SE OF THE RIDGE...WITH THE EXCEPTION OF NE-E 15 KT WINDS S OF 22N E OF 75W. WINDS ARE SE-S 10-15 KT N OF THE RIDGE E OF 73W...AND SW 5-10 KT W OF 73W. THE OBSERVATIONS ARE REPORTING SEAS IN THE 5-7 FT RANGE S OF THE RIDGE E OF THE BAHAMAS...AND 1-3 FT S OF THE RIDGE W OF THE BAHAMAS. N OF THE RIDGE SEAS ARE IN THE 2-4 FT RANGE EXCEPT W OF 79W WHERE LOWER SEAS OF 2-3 FT ARE OBSERVED. SCATTERED TSTMS ARE NOTED OVER THE NE PORTION OF THE ZONES N OF ABOUT 27N E OF 73W TO THE S OF A SHORTWAVE TROUGH PASSING JUST TO THE N OF THE FORECAST WATERS. FOR THIS FORECAST PERIOD...THE RIDGE WILL BE THE DOMINANT WEATHER FEATURE FOR THE AREA. MID/UPPER LEVEL RIDGING OVER THE WESTERN PORTION OF THE AREA WILL BECOME STRETCHED NE TO SW THROUGH FRI AS A LARGER AREA OF UPPER LEVEL RIDGING IN THE EASTERN ATLC BUILDS WESTWARD FORCING AN ELONGATED MID/UPPER LEVEL CYCLONIC CIRCULATION IN BETWEEN BOTH RIDGES TO TRANSLATED NORTHWESTWARD AND SHEAR OUT THROUGH WED. THE RIDGE OVER THE WRN ATLC THEN BECOMES AN ANTICYCLONIC CIRCULATION AT 28N73W BY SAT. THE SRN TAIL END OF THE CYCLONIC CIRCULATION WILL PINCH OFF TO A RATHER ILL-DEFINED UPPER LEVEL CYCLONIC CIRCULATION THAT MOVES SW ACROSS THE NRN CARIBBEAN SEA THROUGH EARLY WED...THEN TRACKS MORE SW ACROSS THE SW PART OF THE SEA LATE THU THROUGH SAT. THIS UPPER LEVEL SET UP WILL FORCE THE SURFACE RIDGE CURRENTLY FROM BERMUDA TO S FLORIDA WILL TO SHIFT NWD TO NEAR 28N BY TUE...AND REMAIN THERE THROUGH THE END OF THE UPCOMING WEEK KEEPING CONTROL OF THE CURRENT WIND REGIME OVER THE FORECAST WATERS. THE EXCEPTION WILL BE SEEN WITH THE E WINDS S OF THE RIDGE BETWEEN THE SE BAHAMAS AND HISPANIOLA REACHING SPEEDS OF 15-20 KT WHILE SPREADING WESTWARD SOME THROUGH WED AS THE PRES GRADIENT THERE TIGHTENS SOME. THE GRADIENT THEN SLACKENS ENOUGH THU AND FRI TO ALLOW FOR THE WINDS TO DIMINISH TO 10-15 KT. CARIBBEAN SEA AND TROPICAL N ATLC W OF 55W... THE TROPICAL WAVE...REMNANTS OF TROPICAL DEPRESSION SEVEN...IS ROUGHLY ALONG A PSN FROM JUST S OF THE WINDWARD PASSAGE S TO NEAR 11N78W MOVING W AT 20 KT. SATELLITE IMAGERY SHOWS NUMEROUS SHOWERS AND TSTMS FROM WITHIN ABOUT 150 NM OF THE WAVE N OF 14N ...AND ALSO E OF THE WAVE N OF 15N BETWEEN THE WAVE AND 71W. AN ASCAT PASS FROM 1418 UTC NICELY REVEALED THE SHARP WIND SHIFT ASSOCIATED WITH THE WAVE. GUSTY WINDS TO 30 KT ARE VERY POSSIBLE WITH THE CONVECTION. THE TROPICAL WAVE IS FORECAST TO REACH FROM 21N81W TO WEAK LOW PRES 1010 MB AT 12N81W TUE MORNING...TO ALONG 85W WITH LOW PRES 1010 MB JUST INLAND NE COAST OF HONDURAS WED MORNING...THEN IS FORECAST TO MOVE INLAND THE YUCATAN PENINSULA AND BELIZE EARLY THU. FORECAST GUIDANCE SUGGESTS THAT LOW PRES MAY FORM ALONG THE WAVE AS IT MOVES ACROSS THE WRN CARIBBEAN BEFORE MOVING INLAND. HOWEVER...THERE IS UNCERTAINTY AS TO THE TIMING AND INTENSITY OF THIS LOW IF IT DOES FORM. IF A LOW FORMS ALONG THE WAVE THEN ITS IMPACTS ON WINDS AND SEAS IN THE WRN CARIBBEAN SEA MAY BE DIFFERENT THAN WHAT IS PRESENTLY ADVERTISED IN THE LATEST OFFSHORE WATERS FORECAST. FUTURE FORECAST ARE SUBJECT TO UPDATES AND/OR REVISIONS BASED ON THIS POSSIBLE UPCOMING SCENARIO WITH TROPICAL WAVE. A TIGHT GRADIENT SUPPORTING NE-E WINDS OF 20-25 KT AS INDICATED BY THE MORNING ASCAT PASS...AND BY CENTRAL CARIBBEAN BUOY 42058 AT 15N75W WILL PRECEDE AND FOLLOW THE WAVE NAMELY IN THE AREA OF THE ASSOCIATED OBSERVED CONVECTION. ELSEWHERE BEHIND THE WAVE...E-SE WINDS OF 15-20 KT ARE NOTED FROM 13N-18N AS FAR E AS 70W WITH SEAS IN THE RANGE OF 5-7 FT. FOR THIS FORECAST PERIOD WILL MAINTAIN CONTINUITY AS WITH FORECAST FROM YESTERDAY AND LEANS TOWARDS A BLEND OF THE GFS/ECMWF MODEL GUIDANCE FOR THE TROPICAL WAVE POSITIONS ACROSS THE CARIBBEAN AS BOTH MODELS ARE IN CLOSE AGREEMENT. FOR WINDS ASSOCIATED WITH THE WAVE WILL FOLLOW GFS GUIDANCE MORE CLOSELY THAN OTHER GUIDANCE DUE ITS GREATER COVERAGE OF 20-25 KT WITH THE WAVE BEING MORE REPRESENTATIVE OF THE PRESENT OBSERVED ONGOING CONDITIONS...AND WITH THAT AS FORECAST. AGAIN WINDS AND SEAS FOR THIS FORECAST MAY HAVE TO BE ADJUSTED TO REFLECT THE IMPACTS OF LOW PRES THAT MAY FORM ON THE WAVE AND ANY SUBSEQUENT INTENSIFICATION THAT MAY OCCUR WITH IT AS TRACKS ACROSS THE WRN CARIBBEAN SEA THROUGH THE NEXT FEW DAYS. THE TROPICAL WAVE ASSOCIATED WITH WEAK BROAD LOW PRES SYSTEM ON THE FAR EASTERN ATLC IS FORECAST TO MOVE NW ACROSS THE NORTHERN PORTION OF THE TROPICAL N ATLC ZONES WED AND THU BEFORE LIFTING NNE FAR INTO THE N CENTRAL ATLC HIGH SEAS. LITTLE IN THE WAY OF ANY SIGNIFICANT WINDS AND SEAS WILL EXPECTED OVER THAT PORTION OF THE FORECAST WATERS. THE TIGHTER GRADIENT ASSOCIATED WITH IT SHOULD STAY N OF THE OFFSHORE WATERS...AND IN THE CENTRAL HIGH SEAS AREA. 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 AGUIRRE