000 AXNT20 KNHC 211733 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 105 PM EST SAT DEC 21 2013 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1700 UTC. ...SPECIAL FEATURES... GALE FORCE WINDS CONTINUE ACROSS A SMALL PORTION OF THE SW CARIBBEAN SEA...NORTH OF THE COAST OF COLOMBIA...DUE TO STRONG PRESSURE GRADIENT INDUCED BETWEEN A STRONG WEST ATLANTIC RIDGE CENTERED ON A 1033 MB HIGH NE OF BERMUDA NEAR 35N54W...AND A BROAD AREA OF LOW PRES NEAR 1008 MB ACROSS NORTHERN COLOMBIA. OVERNIGHT AND MORNING ASCAT PASSES HAVE SHOWN MINIMAL GALES OCCURRING WITHIN 100 NM OF THE COAST OF COLOMBIA...EMBEDDED IN A BROADER AREA OF 25-30 KT TRADEWINDS OCCURRING SOUTH OF 14N OFF THE COAST OF COLOMBIA. GALE FORCE WINDS IN THE AREA ARE EXPECTED TO PERSIST UNTIL SUN MORNING. A STRONG COLD FRONT IS MOVING ACROSS W TEXAS THIS MORNING...AND IS FORECAST TO MOVE INTO THE NW GULF OF MEXICO COASTAL WATERS THIS EVENING AND REACH FROM NEAR THE MOUTH OF THE MISSISSIPPI RIVER TO TAMPICO MEXICO SUNDAY AFTERNOON AND THEN REACH FROM THE FLORIDA PANHANDLE TO CENTRAL BAY OF CAMPECHE LATE MONDAY. STRONG HIGH PRES AND COLD AIR WILL BEGIN TO BUILD S AND SE BEHIND THE FRONT LATE SUN AND MONDAY...WITH STRONG NORTHERLY WINDS ACROSS NW AND W PORTIONS EXPECTED TO INCREASE TO GALE FORCE ACROSS SW PORTIONS BY MONDAY MORNING. SEE LATEST NWS HIGH SEAS FORECAST UNDER AWIPS/WMO HEADERS MIAHSFAT2/FZNT02 KNHC FOR MORE DETAILS ON BOTH OF THESE GALE EVENTS. ...ITCZ/MONSOON TROUGH... THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM THE AFRICAN COAST NEAR 6N10W TO 4.5N27W TO THE COAST OF SOUTH AMERICA NEAR 3.5N52W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS OCCURRING WITHIN 60 NM EITHER SIDE OF ITCZ BETWEEN 17W AND 24W. ...DISCUSSION... GULF OF MEXICO... A STRONG WEST ATLANTIC RIDGE CONTINUES TODAY...EXTENDING FROM A 1033 MB HIGH CENTERED NE OF BERMUDA...WEST SOUTHWESTWARD ACROSS THE NORTHERN GULF. A COLD FRONTAL SYSTEM AND AN ASSOCIATED DEEPENING LOW PRESSURE SYSTEM MOVING ACROSS WEST TEXAS THIS MORNING AND COMBINING WITH THE ATLANTIC RIDGE TO PRODUCE FRESH TO STRONG S TO SE WINDS ACROSS THE MAJORITY OF THE BASIN. MOISTURE EMBEDDED IN THIS SOUTHERLY FLOW IS CONVERGING ACROSS NORTHWEST PORTIONS AND COOLER WATERS TO PRODUCE BROKEN TO OVERCAST LOW AND MIDDLE CLOUDS. NUMEROUS OIL RIGS AND COASTAL OBS ACROSS COASTAL TEXAS AND SW LOUISIANA WERE REPORTING VISIBILITIES 2 TO 4 NM IN FOG AND DRIZZLE. ADDITIONAL PATCHES OF LOW CLOUDS WERE NOTED OVER THE NE GULF NEAR THE FLORIDA BIG BEND. OTHERWISE MOSTLY CLEAR SKIES PREVAIL. IN THE UPPER LEVELS...RIDGE AXIS EXTENDS FROM AN ANTICYCLONE OVER COLOMBIA NORTHWARD ALONG 80W. SOUTHWESTERLY FLOW ON THE BACKSIDE OF THE RIDGE AND WELL E OF A SHARP UPPER LEVEL TROUGH OVER EASTERN NEW MEXICO AND WEST TEXAS IS PROVIDING FAVORABLE DYNAMICS ALOFT FOR VERY INCREASING CONVECTION ACROSS EASTERN TEXAS...AHEAD OF THE FRONT. THE COLD FRONT IS FORECAST TO MOVE OFF THE TEXAS COAST LATE THIS AFTERNOON--EARLY EVENING WITH A MODEST WIND SHIFT... WITH A REINFORCING STRONG NORTHERLY SURGE SLATED TO MOVE OFF LATE SUN ACCOMPANIED BY GALES ACROSS SW PORTIONS MONDAY MORNING. CARIBBEAN SEA... AS MENTIONED ABOVE...THE STRONG ATLANTIC RIDGE AND RESULTANT PRESSURE GRADIENT IS PRODUCING FRESH TO STRONG TRADEWINDS ACROSS THE BASIN EAST OF 80W...WHILE MODERATE SOUTHEASTERLY FLOW IS OPENING UP ACROSS NW PORTIONS...AND FLOWING INTO THE GULF OF MEXICO. DRY AND STABLE CONDITIONS ALOFT GENERALLY PREVAIL ACROSS THE BASIN...WITH MODEST LLVL MOISTURE CONVERGING ACROSS CENTRAL PORTIONS RESULTING IN ISOLATED TO SCATTERED FAST MOVING SHOWERS WITH LITTLE VERTICAL EXTENT. SIMILAR SHOWERS WERE NOTED ACROSS THE GULF OF HONDURAS...BELIZE... HONDURAS...AND NICARAGUA. STABLE AND BREEZY CONDITIONS ARE EXPECTED TO PERSIST THROUGH THE WEEKEND. ...HISPANIOLA... SCATTERED LOW TOPPED SHOWERS ARE ACROSS THE MONA PASSAGE AND ATLANTIC COASTAL WATERS OF PUERTO RICO AND MOVING RAPIDLY INTO E PORTIONS OF THE DOMINICAN REPUBLIC THIS MORNING...EMBEDDED IN MODERATE TO FRESH TRADEWIND FLOW. GENERALLY STABLE CONDITIONS ARE EXPECTED THROUGH THE WEEKEND AS STRONG UPPER LEVELS SUBSIDENCE PREVAILS. THE STRONG SUBSIDENCE IS REFLECTED IN VERY DRY AIR ABOVE 700 MB IN THE 12Z SAN JUAN RAOB. ATLANTIC OCEAN... THE STRONG ATLANTIC RIDGE CENTERED ON A 1033 MB HIGH NEAR 35N54W IS PRODUCING FRESH TO STRONG ENE TRADEWINDS BETWEEN 45W AND 70W...AND CONTINUES WWD THROUGH THE SOUTHEAST BAHAMAS. OTHERWISE...FAIR WEATHER PREVAILS OVER THE BAHAMAS AND WESTERN ATLANTIC IN LIGHT TO MODERATE SOUTHEAST WINDS. A SURFACE TROUGH CENTERED OVER THE CENTRAL TROPICAL ATLANTIC EXTENDS FROM 26N46W TO 10N45W. SCATTERED LOW TOPPED SHOWERS ARE WITHIN 120 NM EITHER SIDE OF THE TROUGH AXIS...EXCEPT FROM 23N TO 27N WHERE SCATTERED MODERATE TSTORMS ARE OCCURRING DUE TO THE INTERACTION OF THE ENHANCED LLVL WINDS AND A STATIONARY UPPER TROUGH. ANOTHER SURFACE TROUGH WAS NOTED FROM 31N34W TO 22N37W WITH SIMILAR SHOWER ACTIVITY NOTED. A LARGE MID TO UPPER LEVEL LOW IS CENTERED OVER THE E ATLANTIC NEAR 25N28W AND HAS BEGUN TO SHIFT NE AND LIFT OUT. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WERE OCCURRING E OF THE LOW...FROM 23N-32N BETWEEN 20W-31W. THE WESTERN MOST TROUGH IS FORECAST TO SHIFT GRADUALLY W DURING THE NEXT FEW DAYS AND REACH 60W BY LATE MONDAY...WHILE THE RIDGE SHIFTS SLIGHTLY E. THIS WILL RESULT IN WINDS GRADUALLY DIMINISHING W AND NW OF THE TROUGH...AND REMAIN FRESH TO STRONG N AND E OF THE TROUGH. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ STRIPLING