000 AGXX40 KNHC 201851 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 251 PM EDT SUN SEP 20 2009 GULF OF MEXICO... THE PESKY DEEP LAYERED LOW OF THE PAST WEEK HAS FINALLY LIFTED OUT TO THE NNE...AND IS ALLOWING A NE TO SW RIDGE SLOWLY BUILD ACROSS THE NORTHERN GULF...AND IS EXPECTED TO PERSIST THROUGH EARLY TUE...THEN THE RIDGE SHIFTS NE OF AREA ALLOWING A COLD FRONT TO THE TX COAST WED...WHICH THEN WEAKENS AND DRAGS ALONG THE N GULF COAST THROUGH THU. NE TO E FLOW OF AROUND 15 KT WITH POCKETS SLIGHTLY HIGHER WED AND THU WILL BUILD SEAS 4 TO 5 FT FROM THE FL STRAITS TO THE NRN BAY OF CAMPECHE. A BROAD INVERTED TROUGH INDUCED OVER THE SOUTHERN WATERS WILL ACT TO ENHANCE THIS FLOW IN AN OTHERWISE WEAK GRADIENT...AND WILL PERSIST THROUGH THE PERIOD. SW N ATLC... ALOFT...AN UPPER TROUGH WITH TWO UPPER VORT DUMBELLING AROUND EACH OTHER IS BRUSHING THE NORTHEAST CARIBBEAN AND ENHANCING REGIONAL CONVECTION THERE. THIS TROUGH WILL ROTATE MORE NE TO SW OVER THE NEXT 48 HOURS...SHIFT SLIGHTLY E AND GRADUALLY WEAKEN THROUGH MID WEEK. AN UPPER RIDGE AXIS UPSTREAM EXTENDS ACROSS SE FL AND THE NW BAHAMAS AND WILL BE THE CULPRIT TO NUDGE THE UPPER TROUGH EWD. AT THE LOW LEVELS A TROUGH N OF 23N ALONG 71/72W...THE REMNANTS OF FRED...IS EXPECTED TO MOVE WNW AND REACH THE NE FL COAST LATE TUE. SELY WINDS NEAR 20 KT AND SEAS NEAR 8 FT STILL TRAIL THE NRN HALF OF THIS TROUGH...WHERE THE LLVL SWIRL OF FRED HAD FILLED AND BECOME ELONGATED. ELY WINDS UNDER CUTTING THIS TROUGH HAVE BROUGHT 15 KT ELY TRADES THROUGH THE SRN BAHAMAS AND INTO THE FLORIDA STRAITS TODAY...BUILDING SEAS 3 TO 5 FT...AND WILL BE ENHANCED SLIGHTLY OVER THE NEXT FEW DAYS AS HIGH PRESSURE ATTEMPTS TO BUILD INTO THE AREA BEHIND THE TROUGH OF FRED. ESE TRADES OF AROUND 15 KT AND SEAS 5-7 FT IN SELY SWELL WILL GENERALLY PREVAIL ACROSS THE WATERS E OF 70W AS HIGH PRESSURE RETURNS NEXT FEW DAYS. CARIBBEAN AND TROPICAL N ATLC... AN UPPER CYCLONE OVER THE NW CARIBBEAN CONTINUES TO WEAKEN WHILE MOVING WESTWARD...AND IS INTERACTING WITH ABUNDANT MOISTURE TO ENHANCE CONVECTION W OF 80W. LIGHT TO MODERATE TRADES PREVAIL ACROSS THE NW CARIB UNDERNEATH THIS...BUT WITH GUSTY WINDS IN CONVECTION. THE TROUGH ACROSS THE NE CARIBBEAN.OTHERWISE E-NE TRADES COVER THE REMAINDER OF THE BASIN...WITH 20-25 KT TRADES ARE WITHIN 5 DEGREES OF COLOMBIA...AND ENHANCED ALONG THE COAST AT 25 KT WITH QUIKSCAT SHOWING SOME ISOLATED 30 KT FLAGS. ONLY MINOR FLUCTUATIONS IN THIS PATTERN ARE EXPECTED DURING THE NEXT 48 HOURS. A TROPICAL LOW NEAR 15.5N45.5W REMAINS EMBEDDED WITHIN AN ELONGATED NE TO SW CIRCULATION...LIKELY WITH PIECES OF TROPICAL WAVE ROTATING UP AND OVER THIS BROAD FEATURE...WHICH IS LIKELY A MERGER OF AT LEAST TWO TROPICAL WAVES. THE ENVELOPE OF THIS LOW/TROPICAL WAVE(S) IS EXPECTED TO MOVE WNW DURING THE NEXT 48 HOURS...AND WILL LIKELY CONTINUE TO SHED PERTURBATIONS...MOISTURE...AND ENERGY TO THE W AND NW. THE PRESSURE GRADIENT TO THE NORTH OF THIS FEATURE CONTINUES TO YIELD A BROAD FILED OF 20-25 KT WINDS AND SEAS 8-10 FT BETWEEN ROUGHLY 35W-55W...AND WILL SHIFT WNW AND DIMINISH SLIGHTLY NEXT 48 HRS. ATLC... .NONE. CARIBBEAN... .NONE. GULF OF MEXICO... .NONE $$ FORECASTER STRIPLING