000 AGXX40 KNHC 191900 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 300 PM EDT SAT SEP 19 2009 GULF OF MEXICO... FAIRLY DEEP LAYERED CYCLONE WHICH HAS PERSISTED ACROSS THE GULF STATES AND NORTHERN GULF OF MEXICO FOR NEARLY A WEEK CONTINUES TO GRADUALLY FILL AND WILL BEGIN TO LIFT OUT TO THE N THIS EVENING WITH ANY INFLUENCE ON THE GULF MARINE WEATHER WANING BY LATE SUN. A WEAK RIDGE WILL BUILD W AND SW ACROSS THE GULF MON AND TUE. THIS RIDGE IS REPLACED BY ANOTHER RIDGE BUILDING SE OUT OF THE SRN PLAINS BY WED. THIS WILL ALLOW LIGHT E TO SE RETURN FLOW TO GRADUALLY BACK INTO THE E AND NE LATE TUE AND CONTINUE INTO WED. ELSEWHERE A BROAD AND INNOCUOUS TROUGH WILL DEVELOP OVER THE E CENTRAL GULF SUN AND CONTINUE INTO MON. SW N ATLC... DISSIPATING TROUGH THROUGH NW BAHAMAS HAS ROTATED CLOCKWISE TODAY...WITH N PORTION SHIFTING SE...AND SW PORTION MOVING INTO EXTREME SE FLORIDA...WHERE ACTIVE WEATHER CONTINUES. THIS FEATURE WILL DISSIPATE DURING THE NEXT 24 HOURS AS HIGH PRESSURE BUILDS MODESTLY ACROSS THE SUNSHINE STATE AND INTO THE ERN GULF. THE REMNANTS OF TC FRED...AN ELONGATED SWIRL OF LOW CLOUDS IN SATELLITE IMAGERY...WAS ALONG 70W...WITH AT LEAST TWO LOW LEVEL CENTERS DEPICTED...WITH THIS PARENT TROUGH MOVING WNW 10-12 KT. A MORNING QUIKSCAT PASS STILL SHOWED 20-25 KT WINDS WITH THE TIGHT LLVL CIRCULATION...BUT THIS HAS SINCE BECOME ELONGATED N TO S...AND 20 KT WINDS WILL LIKELY BECOME CONFINED TO THE E PORTIONS OF THE TROUGH WITHIN NEXT 24 HOURS. MAX SEAS STILL ESTIMATED TO BE NEAR 8 FT IN FORMER NE QUAD OF LOW...AND WILL SUBSIDE VERY SLOWLY TO LESS THAN 8 FT BY 24 HOURS. THIS TROUGH IS EXPECTED TO MOVE WNW TO ALONG 73W WITHIN 24 HOURS...77W WITHIN 48 HOURS...AND ALONG 80W BY 72 HOURS. HIGH PRES WILL BUILD ACROSS THE AREA FROM THE E BEHIND THIS TROUGH WITH E-SE WINDS 15 KT AND ISOLATED AREAS OF 20 KT WINDS MON INTO TUE...WHICH SUBSIDE ON WED. THERE WAS A LOW LEVEL CONVERGENCE ZONE DURING THE PAST 36 HOURS BEHIND THIS TROUGH...CURRENTLY EXTENDING FROM ALONG 65W N OF PUERTO RICO...SE ACROSS THE EXTREME NE CARIBBEAN...TO ALONG 14N E OF BARBADOS...AND IS DEPICTED BY AN ELONGATED CLOUD BAND IN SATELLITE IMAGERY. RECENT QUIKSCAT PASSES HAVE SHOWN 20-25 KT WINDS...SOME LIKELY CONTAMINATED BY SHOWER ACTIVITY...ALONG THE LEADING EDGE OF THIS LONG BAND...WITH 20 KT ELY FLOW BEHIND IT FOR SEVERAL DEGREES. SEAS BEHIND THIS BAND WERE BUILDING 7-8 FT IN NELY WIND SWELL. THIS WILL SHIFT W AND NW NEXT 48 HOURS AND GRADUALLY DIMINISH. CARIBBEAN AND TROPICAL N ATLC... THE GRADIENT BETWEEN HIGH PRESSURE OVER THE SUBTROPICAL ATLANTIC AND A TROPICAL LOW NEAR 13N43W WAS PRODUCING A BROAD AREA OF 20-25 KT WINDS E OF 50W...PER MORNING SCATTEROMETER PASSES... WITH SOME VERY SMALL AND ISOLATED SPOTS OF NEAR 30 KT POSSIBLE IN SHOWERS WITHIN 240 NM N OF THIS LOW. SEAS ACROSS THIS REGION WERE IN THE 7-10 FT RANGE IN A MIX OF SE AND NE SWELLS. THIS TROPICAL LOW STILL APPEARS TO CONSIST OF TWO SEPARATE CYCLONIC CENTERS...ONE NEAR THE SURFACE AS INDICATED ABOVE...AND ANOTHER MORE MID LEVEL CENTER OFF ABOUT 3 DEGREES TO THE NE...CREATING AN ELONGATED WIND FIELD. THIS AREA OF PRESSURE GRADIENT INDUCED WINDS WILL SHIFT SLOWLY WNW WITH THIS ELONGATED LOW...AS THE LOW MOVES WNW NEXT 12 TO 24 HOURS...THEN MORE NW FOR THE NEXT FEW DAYS. THIS IS STILL SOME CHANCE FOR TROPICAL DEVELOPMENT OF THIS SYSTEM...BUT REGARDLESS...A BROAD AREA OF DISTURBED WEATHER WILL CONTINUE N...E AND SE OF THIS SYSTEM FOR THE NEXT 48 HOURS...WITH VERY ROUGH AND CONFUSED SEAS AT 8 FT AND HIGHER... AND SOME AREAS FLUCTUATING AT 10-11 FT IN HEAVY SQUALLS AND TSTMS. ACROSS THE CARIBBEAN...THE REMNANTS OF FRED AND RESULTANT WEAK RIDGING N OF THE AREA HAVE INTERRUPTED THE NORMAL TRADE WIND PATTERN ACROSS THE ENTIRE CARIBBEAN LEAVING 10-15 KT FLOW ACROSS THE BASIN...WITH THE EXCEPTION OF 15 TO 20 KT WINDS WITHIN A FEW DEGREES OF THE COAST OF COLOMBIA. SQUALLY WEATHER IS MOVING INTO THE PASSAGES OF THE EXTREME NE CARIBBEAN IN ASSOCIATION WITH THE CONVERGENCE BAND DISCUSSED ABOVE...AND ACTIVE WEATHER ASSOCIATED WITH AN UPPER LOW CONTINUE ACROSS THE FAR W AND NW CARIBBEAN...SHIFTING W. AS HIGH PRESSURE BUILDS BEHIND THE REMNANTS OF FRED...FRESH TRADES WILL RETURN TO THE SRN CARIBBEAN SUN THROUGH WED WITH WINDS NEAR 20 KT AND SEAS GRADUALLY BUILDING TO NEAR 8 FT...WHILE THE REST OF THE BASIN IS AROUND 15 KT AND SEAS 5 FT OR LESS. ATLC... .NONE. CARIBBEAN... .NONE. GULF OF MEXICO... .NONE $$ FORECASTER STRIPLING