000 AGXX40 KNHC 021803 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT SAT AUG 2 2008 MARINE WEATHER DISCUSSION FOR GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. GULF OF MEXICO...SATELLITE IMAGERY AND SURFACE OBS FROM THE N CENTRAL AND NE GULF OF MEXICO SUGGEST THAT A BROAD AREA OF WEAK LOW PRES...ATTENDED BY SCATTERED TO NUMEROUS SHOWERS AND TSTMS...HAS FORMED S OF PANAMA CITY THIS MORNING. SEVERAL MODELS HAVE RECENTLY BEEN FORECASTING THIS DEVELOPMENT...BUT THERE IS HARDLY A CONSENSUS AMONGST ALL THE GUIDANCE. FOR EXAMPLE...THE LAST SEVERAL RUNS OF THE GFS AND NAM HAVE BEEN MOST ADAMANT IN DEVELOPING THIS FEATURE...WITH THE ECMWF NOW COMING ON BOARD. HOWEVER...THE GFS ENSEMBLES AS WELL AS THE CMC AND UKMET MODELS SHOW BARELY A HINT OF THIS SYSTEM WHICH DOES RAISE SOME DOUBT AS TO HOW SIGNIFICANT THIS FEATURE MAY ULTIMATELY BE. GIVEN RECENT TRENDS...THE CURRENT FORECAST PACKAGE WILL RELY MORE HEAVILY ON THE GFS/NAM/ECMWF MODEL CONSENSUS...DEPICTING A BROAD AREA OF WEAK LOW PRES MOVING LITTLE INITIALLY AND THEN DRIFTING WWD JUST S OF THE N CENTRAL AND PERHAPS NW GULF COAST LATE THIS WEEKEND AND EARLY NEXT WEEK. HAVE INDICATED WINDS OF 20 TO 25 KT WITHIN 90-120 NM OF THE LOW AND SEAS BUILDING TO 4 TO 7 FT ALONG WITH SCATTERED TO NUMEROUS SHOWERS AND TSTMS. SHOULD THE SYSTEM MATURE FURTHER...FUTURE PACKAGES WILL HAVE TO INDICATE AN INCREASE WINDS AND SEAS. OTHERWISE...A WEAK RIDGE AXIS ROUGHLY ALONG 25N SHOULD MOVE LITTLE THROUGH MON...FOLLOWED BY SUBTROPICAL HIGH PRES BUILDING INTO THE NE WATERS IN THE WAKE OF THE SFC LOW DESCRIBED ABOVE. THEREAFTER...MODELS AGREE ON A RIDGE AXIS LYING BETWEEN 28N AND 29N THROUGH THU NEXT WEEK. THUS...OUTSIDE OF THE SFC LOW FORMING OVER THE N CENTRAL GULF...LIGHT WINDS OF 10 TO PERHAPS 15 KT SHOULD COVER MOST OF THE GULF WITH SEAS OF 1 TO 3 FT THROUGH MON. IN THE WAKE OF THE LOW...GUIDANCE SHOWS 4 TO 7 FT SEAS PERSISTING OVER THE NE WATERS INTO EARLY MON BEFORE SUBSIDING. AFTER THE LOW MOVES INLAND EARLY TUE...A WEAK PRES PATTERN ACROSS THE GULF SHOULD FAVOR LIGHT WINDS AND SEAS OF 1 TO 3 FT EXCEPT OVER THE SW WATERS WHERE GUIDANCE IS INDICATED SLIGHTLY STRONGER WINDS AND SEAS OF 3 TO 5 FT. SW N ATLC/TROPICAL N ATLC...THE CHIEF CONCERN THIS PERIOD WILL SURROUND THE FUTURE EVOLUTION OF A WELL-ORGANIZED TROPICAL WAVE ALONG 45W AND AN ASSOCIATED SFC LOW NEAR 19N45W...WHICH ARE MOVING W AT 15 TO 20 KT. ALTHOUGH MODEL GUIDANCE OFFERS A MIXED PROGNOSIS FOR DEVELOPMENT...CURRENT TPC PRODUCTS INDICATE A REASONABLE CHANCE OF TROPICAL CYCLONE FORMATION DURING THE NEXT 48 HOURS. GIVEN RECENT TRENDS AND THE CURRENT TPC PROBABILITY FOR GENESIS...THE AFTERNOON PACKAGE WILL LIKELY INDICATE INCREASING WINDS AND SEAS OF 20 TO 25 KT AND 8 TO 12 FT SEAS OVER THE NE PART OF THE AREA LATE SUN AND MON FOLLOWED BY DIMINISHING WINDS AND SEAS TUE. IN ADDITION...ANOTHER SUSPICIOUS AREA OF DISTURBED WEATHER NEAR 12N29W IS MOVING W 15 TO 20 KT AND IS BEING MONITORED FOR SIGNS OF DEVELOPMENT. WITH NO GUIDANCE INDICATING THE POTENTIAL FOR DEVELOPMENT AND WITH TPC GENESIS PROBABILITIES RATED AS SLIGHT ...THE CURRENT PACKAGE WILL INDICATE ONLY A WAVE PASSAGE EARLY OR MIDDLE NEXT WEEK. OUTSIDE OF THESE AREAS...NE TO E WINDS OF 10 TO 15 KT WILL BE COMMON EXCEPT 15 TO 20 KT BETWEEN 12N AND 18N EARLY NEXT WEEK. SEAS WILL GENERALLY AVERAGE 5 TO 7 FT EXCEPT 3 TO 5 FT S OF 10N. OVER THE SW ATLC...MORNING QUIKSCAT IMAGERY SHOWED A LARGE SWATH OF SW 20 KT WINDS N OF 29N BETWEEN 65W AND 80W WITH WAVEWATCH III GUIDANCE SHOWING 4 TO 7 FT SEAS...HIGHEST NE. MODEL GUIDANCE SHOWS THESE WINDS DIMINISHING TO 10 TO 15 KT WITHIN 24 HOURS IN RESPONSE TO A SHORTWAVE TROUGH OVER THE NE PASSING BY. OTHERWISE ...SUBTROPICAL RIDGE AXIS BETWEEN 26N AND 27N SHOULD BEGIN LIFTING SUN AND MON...LYING BETWEEN 29N AND 30N BY MON AFT. EXPECT SEAS TO AVERAGE BETWEEN 3 AND 5 FT OVER THE N WATERS AND E OF THE BAHAMAS WHILE 2 TO 4 FT SEAS ARE THE RULE W OF THE BAHAMAS DURING THIS TIME. TUE THROUGH THU NEXT WEEK...MODEL GUIDANCE SHOWS A SUBTROPICAL RIDGE AXIS LYING FAR N ALONG 30-31N....WITH E TO SE WINDS OF 10 TO 15 KT COVERING MUCH OF THE AREA EXCEPT S TO SW WINDS NEAR THE NE FL COAST. SEAS AVERAGE 3 TO 5 FT OVER THE NRN WATERS AND E OF THE BAHAMAS AND 2 TO 4 FT W OF THE BAHAMAS. OF COURSE...PART OF THE FCST IS CONTINGENT UPON WHAT EVENTUALLY HAPPENS WITH THE TROPICAL WAVE CURRENTLY ALONG 45W. THE GFS SHOWS A VAGUE HINT OF THIS FEATURE REACHING THE SW N ATLC WATERS TUE AND WED NEXT WEEK...THOUGH ITS IMPACT APPEARS MINIMAL. THAT BEING SAID... USERS OF THIS PRODUCT ARE URGED TO MONITORS FUTURE FCSTS IN CASE THIS ASSESSMENT CHANGES. CARIBBEAN...QUIKSCAT IMAGERY SHOWS A CYCLONIC SHEAR TO THE LOW-LEVEL WINDS OVER THE ERN CARIBBEAN THIS MORNING IN ASSOCIATION WITH A TROPICAL WAVE ANALYZED ALONG 68W. AS THE WAVE MOVES W INTO THE CENTRAL AND WRN CARIBBEAN SEA OVER THE NEXT DAY OR TWO...MODELS ARE FORECASTING AN EASTERLY SURGE IN ITS WAKE. IN FACT...THE GFS INDICATES A LARGE AREA OF 20 TO 25 KT WINDS LATE SUN INTO MON FROM 11N TO 18N BETWEEN 70W AND 82W. ALTHOUGH FAIRLY BRIEF...THE SURGE SHOULD CAUSE SEAS TO BUILD TO 7 TO 11 FT OVER THESE AREAS...WITH THE EASTERLY SWELL ARRIVING OVER THE REMAINDER OF THE SW AND NW CARIBBEAN TUE AND WED NEXT WEEK. MODELS ALSO SHOW THE SRN END OF THE WAVE CURRENTLY ALONG 45W MARCHING ACROSS THE NE AND N CENTRAL CARIBBEAN MON EVENING THROUGH WED. IN ITS WAKE...STRONG E TO SE WINDS OF 20 TO 25 KT AND SEAS BUILDING TO 8 FT ARE FCST BY THE GFS AND NOAA WAVEWATCH III MODELS. HOWEVER...THIS OUTCOME IS VERY MUCH CONTINGENT UPON WHAT TYPE OF DEVELOPMENT ULTIMATELY OCCURS IN ASSOCIATION WITH THE LOW NEAR 19N45W. STILL THOUGH...WILL INDICATE SOME INCREASE IN WINDS AND SEAS FOLLOWING THE PASSAGE OF THE SRN END OF THIS WAVE TUE THROUGH THU. WARNINGS... ATLANTIC... NONE. CARIBBEAN... NONE. GULF OF MEXICO... NONE. .FORECASTER KIMBERLAIN. TROPICAL PREDICTION CENTER.