000 AXNT20 KNHC 111745 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT WED MAR 11 2015 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL ANALYSIS. BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...SPECIAL FEATURES... ...GALE WARNING FOR THE SW CARIBBEAN... A GALE WARNING REMAINS IN EFFECT FOR THE COASTAL WATERS OF COLOMBIA FROM 10N TO 13N BETWEEN 74W AND 77W. AN EARLIER SCATTEROMETER PASS CONFIRMED THE PRESENCE OF THESE WINDS WHILE AN ALTIMETER PASS INDICATED SEA HEIGHTS OF AROUND 16 FT IN THE WARNING AREA. THESE HIGH WINDS ARE BEING CAUSED BY THE STRONG PRESSURE GRADIENT BETWEEN THE COLOMBIAN/PANAMANIAN LOW OF 1006 MB AND A 1029 MB HIGH PRES LOCATED EAST OF BERMUDA NEAR 31N58W. GALE CONDITIONS ARE FORECAST TO CONTINUE THROUGH FRI MORNING AS STRONG HIGH PRES ACROSS NEW ENGLAND BUILDS INTO THE FORECAST REGION TO MAINTAIN A STRONG PRES GRADIENT ACROSS THE BASIN. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE TROPICAL ATLANTIC NEAR 5N10W TO 3N13W WHERE THE ITCZ BEGINS AND CONTINUES TO 1N28W TO THE COAST OF SOUTH AMERICA NEAR 1S45W. SCATTERED MODERATE CONVECTION IS NOTED S OF 1N BETWEEN 37W AND 48W. ...DISCUSSION... GULF OF MEXICO... AT 1500 UTC...A COLD FRONT EXTENDS FROM SE LOUISIANA TO A 1012 MB LOW PRES THAT HAS DEVELOPED ALONG THE FRONTAL BOUNDARY NEAR 25N84W TO VERACRUZ MEXICO. CONVECTION HAS INCREASED NEAR THE LOW CENTER DURING THE LAST FEW HOURS WHILE DOPPLER RADAR SHOWS SOME SHOWER ACTIVITY NEAR BROWNSVILLE TEXAS AND OVER NE MEXICO. THE CONVECTION IS LIKELY SUPPORTED BY FORCING FROM A HIGH AMPLITUDE MID TO UPPER LEVEL TROUGH CENTERED OVER CENTRAL MEXICO. THE FRONT WILL DRIFT SLOWLY EASTWARD WHILE THE LOW PRES WILL MOVE N- NE ALONG FRONT AND INTO SW LOUISIANA THU. THE COLD FRONT WILL THEN MOVE SLOWLY E ACROSS THE N GULF TO THE FLORIDA BIG BEND EARLY SUN...WHILE THE S PORTION OF THE FRONT STALLS ACROSS THE E BAY OF CAMPECHE. SURFACE WINDS HAVE SLIGHTLY INCREASE TO 15-20 KT OVER THE NW GULF BEHIND THE FRONT LIKELY IN RESPONSE TO THE DEVELOPING LOW PRES. THE EASTERN GULF IS UNDER THE INFLUENCE OF THE ATLANTIC RIDGE THAT EXTENDS FROM A HIGH PRES LOCATED EAST OF BERMUDA ACROSS FLORIDA INTO THE GULF REGION. MAINLY MODERATE TO LOCALLY FRESH SE WINDS PREVAIL AROUND THE WESTERN PERIPHERY OF THE RIDGE OVER THE EASTERN GULF. CARIBBEAN SEA... GALE CONDITIONS PERSIST NEAR THE COAST OF COLOMBIA. PLEASE SEE SPECIAL FEATURE FOR DETAILS. MODERATE TO FRESH TRADE WINDS ARE NOTED PER SCATTEROMETER DATA ACROSS THE REMAINDER OF THE BASIN WITH THE EXCEPTION OF STRONG WINDS OF 25-30 KT ACROSS THE GULF OF VENEZUELA...AND NE-E WINDS OF 25 KT ACROSS THE ABC ISLANDS. PATCHES OF LOW LEVEL MOISTURE EMBEDDED IN THE TRADE WIND FLOW ARE SEEN ON VISIBLE SATELLITE IMAGERY. SOME OF THEN ARE NOW CROSSING THE UK/US VIRGIN ISLANDS AND MAINLY EASTERN PUERTO RICO. A BROAD HIGH AMPLITUDE UPPER RIDGE COVERS THE CARIBBEAN WITH AN AXIS ALONG 75W...WHICH IS PROMOTING STRONG SUBSIDENCE ACROSS THE AREA. LITTLE CHANGE IN THE WEATHER PATTERN IS EXPECTED DURING THE NEXT TWO DAYS. ...HISPANIOLA... GENERALLY FAIR SKIES WITH POSSIBLE ISOLATED FAST-MOVING SHOWERS DOMINATE THE ISLAND UNDER THE INFLUENCE OF A RIDGE. THESE CONDITIONS WILL PERSIST THROUGH AT LEAST FRIDAY MORNING. ATLANTIC OCEAN... THE MAIN SURFACE FEATURE ACROSS THE ATLANTIC IS THE ABOVE MENTIONED RIDGING EXTENDING FROM A 1029 MB HIGH PRES LOCATED EAST OF BERMUDA NEAR 31N58W. TRADEWINDS ARE GENERALLY 10-20 KT ACROSS MOST OF THE REGION WITH 20-25 KT WINDS OCCURRING JUST NORTH OF THE LEEWARD ISLANDS. A SURFACE TROUGH EXTENDS FROM 31N43W TO 26N51W...THOUGH NO SIGNIFICANT WEATHER IS CURRENTLY ASSOCIATED WITH THIS FEATURE. IN THE UPPER LEVELS...A CUT OFF LOW IS CENTERED NEAR 20N43W. SCATTERED SHOWERS ARE ASSOCIATED WITH THIS FEATURE MAINLY FROM 20-25N BETWEEN 38-46W. DURING THE NEXT COUPLE OF DAYS...THE UPPER-LEVEL LOW WILL DRIFT SLOWLY EASTWARD AND OCCASIONALLY PRODUCE SOME CONVECTION...BUT NO SIGNIFICANT SURFACE FEATURES ARE ANTICIPATED TO FORM. A NEW COLD FRONT WILL EXTENDING MAINLY E-W WILL REACH 31N W OF 60W BY THU. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ GR