000 AGXX40 KNHC 191854 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 255 PM EDT FRI OCT 19 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 SURFACE COLD FRONT THAT ENTERED THE AREA YESTERDAY HAS NOW MOVED TO A PSN FROM NEAR CEDAR KEY FLORIDA SW TO 27N90W WHERE IT BECOMES STATIONARY TO INLAND NE MEXICO. SCATTERED SHOWERS AND A FEW TSTMS ARE ALONG...AND WITHIN 90 NM SE OF THE FRONT. THE LATEST BUOY OBSERVATIONS ARE SHOWING SW-W WINDS OF 5-10 KT JUST TO THE SE OF THE FRONT WITH SEAS OF 2 FT...WHILE NE-E WINDS OF 10-15 KT ARE TO THE NW OF THE FRONT WITH SEAS OF 2 FT...EXCEPT FROM THE FRONT TO 28N W OF 94W WHERE SEAS ARE 4-5 FT. ELSEWHERE TO THE SE OF THE FRONT WINDS ARE VARIABLE 5-10 KT...EXCEPT E-SE 5-10 KT IN THE SW GULF. SEAS THERE ARE 1-2 FT. OBSERVED SEA HEIGHT VALUES ARE VERY CLOSE TO THE LATEST NOAA WAVEWATCH III GUIDANCE SO WILL RELY ON GUIDANCE FOR THIS PACKAGE. WATER VAPOR IMAGERY ALSO SHOWS BROAD MOSTLY MID LEVEL TROUGHING COVERING THE FAR NORTHERN PORTION OF THE GULF WITH AN EMBEDDED SHORTWAVE TROUGH ROTATING THROUGH IT FROM SE ALABAMA SW TO 27N94W. THIS TROUGH WILL PUSHING THE AFOREMENTIONED COLD FRONT TO A POSITION FROM NEAR TAMPA FLORIDA TO 26N90W AND WEAKENING STATIONARY TO S TEXAS BY EARLY TONIGHT. MODELS SUGGEST THAT THE FRONT WILL THEN REACH FROM NEAR FORT MYERS TO 25N90W...AND DISSIPATING STATIONARY TO NE MEXICO BY SAT MORNING. THE FRONT WILL DISSIPATE FROM THE FLORIDA KEYS TO THE FAR S CENTRAL GULF SAT EVENING AS HIGH PRES BEGINS TO BUILD S ACROSS THE EASTERN AND CENTRAL GULF ZONES THROUGH WED. NE-E WINDS INCREASE TO 15-20 KT OVER MUCH OF THE EASTERN AND CENTRAL WATERS MON AND TUE... WHILE INCREASING RETURN SLY FLOW SETS UP OVER THE WESTERN GULF SAT NIGHT THROUGH MON WITH SE-S WINDS OF 15-20 KT AND SEAS BUILDING TO 7 FT THERE AS THE HIGH PRES INTERACTS WITH DEVELOPING LOW PRES OVER THE CENTRAL PLAINS. THE SE-S 15-20 KT WINDS THEN DIMINISH TO 10-15 KT TUE AND WED WITH SEAS LOWERING TO 3-5 FT...HOWEVER...THE NE-E WINDS OF 15-20 KT OVER THE EASTERN AND CENTRAL GULF CONTINUE INTO WED WITH SEAS EXPECTED TO RAISE TO 6 FT ACROSS THOSE PORTIONS. SW N ATLC S OF 31N W OF 65W... THE PRELIMINARY 18 UTC ANALYSIS HAS A WEAK RIDGE EXTENDING FROM NEAR BERMUDA SW TO THE CENTRAL...WHILE A COLD FRONT HAS ENTERED THE FAR NW WATERS OF THE BASIN. A DISSIPATING REMNANT TROUGH... LEFTOVER FROM HURRICANE RAFAEL...IS LIFTING N ALONG A LINE FROM 27N65W TO 27N69W. UPPER DIFFLUENT FLOW OVER THE WESTERN PORTION OF THE AREA AHEAD OF THE GULF OF MEXICO MID/UPPER BROAD TROUGH IS ENHANCING SCATTERED SHOWER AND TSTM ACTIVITY FROM THE BAHAMAS NWD AND BETWEEN 70W AND THE FRONT. BUOYS ARE SHOWING LINGERING NE SWELLS ACROSS THE N CENTRAL AND NE PORTIONS RESULTING IN SEAS OF 5-6 FT. SEAS ARE 3-5 FT IN N TO NE SWELLS OVER THE REMAINDER OF THE AREA N OF THE BAHAMAS AND W OF 70W. THE SWELLS WILL SLOWLY SUBSIDE THROUGH THE WEEKEND AS THEY BECOME MORE E TO SE IN DIRECTION. AS THE PREVIOUSLY MENTIONED MID/UPPER TROUGH TRANSLATES EASTWARD OVER THE NEXT 48 HRS...THE SURFACE COLD FRONT WILL RESPOND BY MOVING TO A PSN FROM NEAR 31N77W TO DAYTONA BEACH EARLY TONIGHT ...FROM NEAR 31N74W TO SE FLORIDA SAT MORNING...AND FROM NEAR BERMUDA THROUGH STRAITS OF FLORIDA SUN EVENING. THE FRONT WILL GRADUALLY DISSIPATE FROM NEAR 27N65W TO THE STRAITS OF FLORIDA MON. THE SCATTERED SHOWERS AND TSTMS ASSOCIATED WITH THE SHORTWAVE TROUGH AS MENTIONED ABOVE WILL ALSO TRANSLATE EASTWARD WITH THE ADVANCEMENT OF THE TROUGH AND FRONT. STRONGER HIGH PRES BUILDS SE IN THE WAKE OF THE FRONT WITH A TIGHTER PRES GRADIENT BRINGING NE-E WINDS OF 15-20 KT TO MUCH OF THE NORTHERN AND CENTRAL WATERS WITH SEAS POSSIBLY BUILDING TO 6-6 FT TUE AND WED OF NEXT WEEK . CARIBBEAN SEA AND TROPICAL N ATLC W OF 55W... THE BROAD CYCLONIC LLVL FLOW ASSOCIATED WITH THE MONSOON TROUGH TROUGH HAS BECOME LESS DEFINED SINCE YESTERDAY...HOWEVER SCATTERED SHOWERS AND TSTMS ARE STILL NOTED IN THE FAR SW PORTION OF THE SEA S OF 14N. WHAT APPEARS TO BE SMALL VORT MAX ASSOCIATED WITH THIS AREA OF WEATHER IS IDENTIFIED TO BE NEAR 11N82W. BOTH BUOY OBSERVATIONS AND PARTIAL ASCAT SHOW RELATIVELY LIGHT CONDITIONS THROUGHOUT WITH SEAS OF 1-3 FT AND TRADES DOWN TO 10-15 KT...EXCEPT E-SE WINDS OF 5 KT IN THE NW CARIBBEAN. THE EXCEPTION IS IN THE TROPICAL N ATLC WHERE NE SWELLS ARE STILL PRODUCING SEAS OF 3-5 FT OVER THE NORTHERN AND CENTRAL PORTIONS OF THOSE WATERS...WHICH IS A LOT LESS THAN IN PREVIOUS DAYS. THE MONSOON TROUGH SEGMENT IN THE SW CARIBBEAN IS FORECAST BY GLOBAL MODELS AND EVEN THE GFS/ECMWF ENSEMBLES TO SPAWN LOW PRES THERE OVER THE NEXT FEW DAYS. THE FORECAST CHALLENGE WILL BE BEGINNING AROUND DAY 3 OF THE FORECAST PERIOD TO DAY 5 WITH THE FORECAST AND INTENSITY OF THE EVENTUAL LOW THAT DOES DEVELOP THERE. RIGHT NOW IT APPEARS THAT SOME FORM OF WEAK LOW PRES WILL FORM IN THE SHORT TERM OF THE FORECAST WITH LITTLE MOVEMENT... THEN BEGIN TO TRACK IN A GENERAL NE DIRECTION NEXT WEEK AS EVEN THE ENSEMBLE GUIDANCE PROGS FROM THE GFS AND ECMWF SUGGEST. FOR THIS FORECAST PACKAGE WILL FORECAST A WEAK 1009 MB TO 1010 MB LOW ALONG THE MONSOON TROUGH NEAR 11N81W BEGINNING IN ABOUT 48 HRS...THEN SHOW MORE OF NE TRACK IN 72 HRS. HIGH UNCERTAINTY REMAINS IN THE FORECAST WITH DAY 3 TO 5. WHETHER THIS FEATURE TURNS OUT TO BE A FULL FLEDGED TROPICAL ENTITY OR NOT...OR WHETHER IT IS TROPICAL FOE A BRIEF TIME SPAN THE MAIN THING TO CONSIDER FOR THE FORECAST WITH RESPECT TO THIS FEATURE WILL BE THE TIGHTENING PRES GRADIENT TO ITS IN RESPONSE TO THE ATLC HIGH PRES THAT BUILDS EASTWARD AS MODEL CONSENSUS SUGGESTS. EXPECT WINDS AND SEAS TO PICK UP OVER MUCH OF THE CENTRAL AND WESTERN CARIBBEAN SEA EARLY NEXT WEEK. WILL HAVE TO WAIT AND SEE HOW THINGS TRANSPIRE WITH THE EVOLUTION OF THIS SYSTEM BEFORE INTRODUCING DEFINITIVE WORDING WITH RESPECT TO WIND VELOCITIES AND SEA HEIGHTS AS TIED INTO THIS FORECAST LOW FEATURE. FOR THE GRIDS THE 12 UTC GFS GUIDANCE WAS BLENDED WITH THE PREVIOUS FORECAST THROUGH LATE ON DAY 3...THEN USED AN EQUAL BLEND OF THE GFS/UKMET/ECMWF FOR DAY 4 ONWARD WITH SOME TWEAKS MADE TO THE DEPICTED CYCLONIC CIRCULATION KEEPING THE HIGH UNCERTAINTY FACTOR IN MIND. NOTE...GRIDDED MARINE FORECAST IS AVAILABLE AT WWW.NHC.NOAA.GOV/TAFB/GRIDDED_MARINE GULF OF MEXICO... .NONE. CARIBBEAN SEA AND TROPICAL N ATLC... .NONE. SW N ATLANTIC... .NONE. FOR ADDITIONAL INFORMATION PLEASE VISIT WWW.HURRICANES.GOV/MARINE $$ FORECASTER AGUIRRE