000 AGXX40 KNHC 310729 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 230 AM EST SAT JAN 31 2009 MARINE WEATHER DISCUSSION FOR GULF OF MEXICO... CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. CURRENT CONDITIONS... A PROGRESSIVE UPPER LEVEL PATTERN IS IN PLACE ACROSS THE REGION...AS A VIGOROUS DEEP TROUGH OVER THE E CONUS AND W ATLC IS QUICKLY BEING EJECTED EASTWARD. THE ASSOCIATED COLD FRONT EXTENDS ACROSS THE SW N ATLC...W CUBA...AND THE YUCATAN PENINSULA. THE FRONT HAS ALREADY SURGED SOUTH OF THE YUCATAN CHANNEL...AND IS NOW ENTERING THE NW CARIBBEAN PER A RECENT ASCAT PASS. IN THE WAKE OF THE FRONT...STRONG GRADIENT WINDS ARE BEING DRIVEN BY SURFACE HIGH PRESSURE OVER SE TEXAS. N TO NE WINDS OF 20 TO 30 KT ARE PRESENT ACROSS MOST AREAS NW OF THE FRONT. THE STRONGEST WINDS ARE IN THE BAY OF CAMPECHE...WHERE LOCAL TERRAIN VARIATIONS ARE FUNNELING THE LOW LEVEL FLOW INTO THE ISTHMUS OF TEHUANTEPEC. IN FACT...THE HIGH-RESOLUTION QUIKSCAT PASS AT 31/0030 UTC DEPICTS ISOLATED GALE-FORCE WINDS IN THE BAY OF CAMPECHE S OF 19N. THE WIND SPEEDS OVER THE GULF...HOWEVER...ARE TRENDING DOWNWARDS AS THE FRONT CONTINUES ITS SOUTHWARD SURGE AND THE PRESSURE GRADIENT SLACKENS WITH THE APPROACH OF THE SURFACE HIGH TO THE NORTH. SREF GUIDANCE HANDLES THIS DOWNWARD TREND WELL...AND CONTINUES IT OVER THE NEXT FEW HOURS. THUS...THE GALE WARNING IN THE BAY OF CAMPECHE ENDED AT 31/0600 UTC. IN THE SW N ATLC...WIND SPEEDS ON EITHER SIDE OF THE FRONT ARE 20 TO 25 KT WITH AN ABRUPT SHIFT FROM SW TO NW ACROSS THE FRONT THERE. SEAS HAVE BUILT UP TO 10 FT IN THE GULF OF MEXICO PER SHIP REPORTS...WITH SEAS UP TO 12 FT IN THE BAY OF CAMPECHE WHERE THE STRONGER WINDS ARE PRESENT. ALSO...A REINFORCING FRONT IS DRAPED ACROSS THE CAROLINAS AND IS CONTINUING TO MOVE SOUTHEASTWARD AS ADDITIONAL SHORTWAVES MOVE THROUGH THE LARGE-SCALE TROUGH. ELSEWHERE...TRADE WINDS CONTINUE TO DECREASE ACROSS THE CARIBBEAN WITH THE APPROACH OF THE FRONT. HOWEVER...THE TRADES CONTINUE OVER THE TROPICAL N ATLC WITH A SURFACE RIDGE NE OF THE AREA...WITH SEA HEIGHTS UP TO 10 FT. TODAY AND TONIGHT... THE FRONT IS FORECAST TO CONTINUE SURGING EASTWARD ACROSS THE WESTERN N ATLC TODAY...WHILE BECOMING DIFFUSE ACROSS THE NW CARIBBEAN BY TONIGHT. THE FRONT WILL CONTINUE TO BE FOLLOWED BY STRONG N WINDS. THIS WILL ESPECIALLY BE THE CASE N OF 28N IN THE SW N ATLC IN THE WAKE OF THE FRONT...WITH THE APPROACH OF THE REINFORCING FRONT. COLD AIR ADVECTION IN THE WAKE OF THIS REINFORCING FRONT WILL CONTRIBUTE TO STRONG LOW LEVEL INSTABILITY TO HELP MIX WINDS ALOFT TO THE SURFACE. OPERATIONAL MODEL TIME-HEIGHT SERIES FOR LOCATIONS IN THE WAKE OF THE REINFORCING FRONT DEPICT 35 KT WINDS EMBEDDED WITHIN THIS UNSTABLE LAYER...AND THUS A GALE WARNING HAS BEEN POSTED FOR PORTIONS OF THE SW N ATLC N OF 28N IN THE WAKE OF THE FRONT. SREF ENSEMBLE GUIDANCE HAS ALSO RECENTLY BEEN TRENDING UPWARD WITH THE GALE POTENTIAL IN THE WARNING AREA. OTHERWISE...NW WINDS OF 20 TO 30 KT WILL BE COMMON IN THE WAKE OF THE REINFORCING FRONT. ALSO...IN THE WAKE OF THE FRONT...SEAS WILL BUILD UP TO 16 FT BY LATE TONIGHT ACROSS PORTIONS OF THE SW N ATLC. SUNDAY... THE FRONT WILL CONTINUE MOVING ACROSS THE W AND CENTRAL ATLC THIS WEEKEND AND WILL WEAKEN FROM S TO N AS THE BULK OF THE UPPER SUPPORT LIFTS N OF THE FORECAST AREA. AS A RESULT...WINDS AND SEAS IN THE WAKE OF THE FRONT WILL RELAX ACROSS THE GULF AND W ATLC. A SURFACE RIDGE WILL TRANSLATE ACROSS THE N GULF INTO THE SW N ATLC THIS WEEKEND. IN RESPONSE...SOUTHERLY RETURN FLOW WILL INCREASE ACROSS THE GULF OF MEXICO...AND TRADE WINDS WILL PICK UP AGAIN ACROSS THE CARIBBEAN. MONDAY THROUGH WEDNESDAY... OPERATIONAL MODELS CONTINUE TO COME INTO AGREEMENT WITH REGARD TO A STRONG STORM SYSTEM TO IMPACT THE FORECAST AREA EARLY NEXT WEEK. THE UPPER LEVEL PATTERN LATE THIS WEEKEND ONCE AGAIN FEATURES A LONGWAVE UPPER TROUGH OVER THE CONUS. A STRONG UPPER LEVEL JET MAXIMUM IS FORECAST TO DIVE SOUTHEAST OF A RIDGE OVER THE W CONUS...HELPING THE UPPER TROUGH DIG SOUTHWARD AND BECOME MORE PROGRESSIVE. THIS JET MAXIMUM IS FORECAST TO COUPLE WITH THE SUBTROPICAL JET STREAM...BRINGING STRONG UPPER LEVEL DIVERGENCE INTO THE GULF REGION. THIS WILL HELP SPIN UP A SURFACE LOW OVER THE N GULF THAT WILL RACE NORTHEASTWARD WHILE DEEPENING. THE LOW WILL ALSO PULL A STRONG COLD FRONT INTO THE NW GULF ON MONDAY...ENTERING THE W ATLC AND W CARIBBEAN ON TUESDAY. THE SYSTEM INDICATED BY THE ECMWF HAS COME MORE IN LINE WITH THE MORE PROGRESSIVE SYSTEM OFFERED BY THE OPERATIONAL GFS. BOTH MODELS CONTINUE TO DEPICT A WEAKER LOW THAN PREVIOUSLY FORECAST. THAT SAID...MODELS CONTINUE TO BACK OFF ON THE COVERAGE OF THE GALE AREAS IN THE WAKE OF THE FRONT...PARTICULARLY IN THE GULF OF MEXICO. GALES STILL APPEAR TO BE LIKELY ACROSS PORTIONS OF THE SW GULF CLOSE TO THE MEXICO COAST FOR MON NIGHT AND EARLY TUE...WHERE LOCAL EFFECTS WILL MODULATE SURFACE WINDS. HOWEVER...TIME-HEIGHT ANALYSES ACROSS THE REMAINDER OF THE GULF INDICATE A SUBSTANTIALLY WEAKER LOW LEVEL JET WHEN THE STRONGER LOW LEVEL MIXING ARRIVES IN THE WAKE OF THE FRONT. OTHER THAN THE IN THE SW GULF...IT APPEARS ANY 35-KT WINDS WILL REMAIN ELEVATED ABOVE 700 MB...WITH RATHER STABLE CONDITIONS BELOW THIS LEVEL. NEVERTHELESS...N TO NE WINDS OF 20 TO 30 KT WILL BE COMMON ACROSS THE GULF FOR MON NIGHT AND EARLY TUESDAY. AS THE FRONT TRAVERSES THE WESTERN N ATLC ON TUESDAY AND WEDNESDAY... THE ATTENDANT SURFACE LOW WILL DEEPEN CONSIDERABLY N OF THE AREA...WITH INCREASING WINDS ON EITHER SIDE OF THE FRONT ON TUESDAY...WITH GALE FORCE WINDS N OF 28N IN THE SW N ATLC ON TUE. A REINFORCING COLD FRONT WILL QUICKLY MOVE EASTWARD ACROSS THE E GULF AND SW N ATLC ON WEDNESDAY. THIS WILL PROVIDE ADDITIONAL GALE FORCE WINDS IN THE SW N ATLC ON WEDNESDAY...AS COLD AIR ADVECTION BEHIND THE REINFORCING COLD FRONT STEEPENS LOW LEVEL LAPSE RATES ALLOWING STRONGER WINDS ALOFT TO MIX TO THE SURFACE. SEAS ARE EXPECTED BUILD UP TO 10 FT IN THE GULF OF MEXICO BY MON NIGHT AND UP TO 16 FT OVER THE SW N ATLC BY TUE NIGHT. ATLANTIC... GALE WARNING AMZ080 TODAY. CARIBBEAN... NONE. GULF OF MEXICO... NONE. FORECASTER COHEN. TROPICAL PREDICTION CENTER.