000 AXNT20 KNHC 162317 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST SUN DEC 16 2012 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 2230 UTC. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH IS ALONG AFRICA ROUGHLY FROM 6N TO 8N WITH NO PORTION OVER WATER. THE INTERTROPICAL CONVERGENCE AXIS EXTENDS FROM THE COAST OF AFRICA AT SIERRA LEONE NEAR 8N13W TO 6N24W TO 3N40W TO THE COAST OF FRENCH GUIANA NEAR THE EQUATOR AND 48W. SCATTERED MODERATE TO STRONG CONVECTION IS LOCATED WITHIN 60-90 NM EITHER SIDE OF A LINE FROM 5N23W TO 7N32W TO 8N44W. SCATTERED MODERATE IS WITHIN AN AREA BOUNDED BY 2N38W TO 6N41W TO 3N44W TO 1N40W TO 2N38W. ...DISCUSSION... GULF OF MEXICO... A MIDDLE TO UPPER LEVEL ANTICYCLONIC CIRCULATION IS POSITIONED OFF OF THE PACIFIC COAST OF MEXICO NEAR 14N102W WITH AN UPPER RIDGE EXTENDING NE ACROSS THE SE GULF TO THE U.S. MID-ATLANTIC REGION. STRONG UPPER LEVEL WESTERLY WINDS OVER THE ENTIRE GULF. SATELLITE DERIVED WINDS INDICATE THE STRONGEST WINDS N OF 28N WITH SPEEDS AS HIGH AS 90-100 KNOTS. A SURFACE COLD FRONT IS LOCATED OVER E TEXAS REACHING FROM TEXARKANA TO THE TEXAS BIG BEND. SCATTERED SHOWERS AND THUNDERSTORMS LOCATED ALONG MOST OF THE TEXAS COASTAL PLAINS APPROACHING THE COASTAL WATERS AS THE FRONT CONTINUES EASTWARD. THE FRONT WILL MOVE FAIRLY RAPIDLY ACROSS THE GULF REACHING FROM SE LOUISIANA TO THE SW GULF MON...THEN WILL WEAKEN AS IT EXTENDS FROM TAMPA FLORIDA TO THE E BAY OF CAMPECHE TUE...EXITING THE SE GULF TUE NIGHT. LOOKING AHEAD...A STRONGER COLD FRONT WILL REACH THE TEXAS COAST THU...MOVING ACROSS THE GULF BY THE END OF THE WEEK INTO NEXT WEEKEND. CARIBBEAN SEA... MODERATE NORTHERLY WINDS ALOFT COVER MOST OF THE WESTERN HALF OF THE CARIBBEAN AROUND THE UPPER RIDGE WHICH EXTENDS OVER THE SE GULF OF MEXICO MENTIONED IN THE SECTION ABOVE. THE LATEST WATER VAPOR SATELLITE IMAGERY SHOWS STRONG SUBSIDENCE AND VERY DRY AIR OVER THE ENTIRE BASIN. THE SOUTHERN END OF A MIDDLE TO UPPER LEVEL TROUGH EXTENDS FROM THE W CENTRAL ATLANTIC TO OVER PUERTO RICO TO THE SW CARIBBEAN. A WEAK AND ILL-DEFINED SURFACE TROUGH IS LOCATED ALONG 77W FROM JAMAICA TO W OF THE COAST OF COLOMBIA. ISOLATED SHOWERS ARE OCCURRING NEAR THE TROUGH AXIS. THIS TROUGH IS MOVING W-NW AT 10-15 KNOTS AND IT MAY DISSIPATE WITHIN THE NEXT 48 HOURS. ATLANTIC OCEAN... OVER THE WESTERN ATLANTIC...NORTHWESTERLY WINDS ALOFT HAVE SPEEDS IN THE 45-60 KNOT RANGE. THESE WINDS ARE OCCURRING AROUND THE PERIPHERY OF AN UPPER LEVEL RIDGE THAT EXTENDS TO THE U.S. MID-ATLANTIC REGION FROM THE SE GULF OF MEXICO. THE REMAINDER OF THE W CENTRAL ATLANTIC IS DOMINATED BY A MIDDLE TO UPPER LEVEL TROUGH WITH THE AXIS EXTENDING THROUGH 32N55W TO PUERTO RICO. THE TROUGH WILL MOVE ABOUT 20 KNOTS TO THE E OVER THE NEXT TWO DAYS. MODERATE TO STRONG SOUTHWESTERLIES ALOFT ARE LOCATED UP TO 25 DEGREES E OF THIS UPPER TROUGH AXIS. BROAD RIDGING EXTENDS ACROSS THE MAJORITY OF THE EASTERN ATLANTIC EXTENDING FROM AN ANTICYCLONIC CIRCULATION OVER THE ITCZ NEAR 8N47W NE TOWARD PORTUGAL. AT THE SURFACE...A 1013 MB LOW IS CENTERED NEAR 21N51W AND IS FORECAST TO DISSIPATE OVER THE NEXT 24 HOURS WHILE MOVING TO THE NE. A TROUGH EXTENDS FROM 18N56W TO THE LOW TO THE NE THROUGH 32N42W AND BEYOND. SCATTERED MODERATE CONVECTION IS WITHIN 90-180 NM OF THE TROUGH AXIS N OF 26N. ANOTHER SURFACE TROUGH IS E OF THE CARIBBEAN EXTENDING FROM 16N52W TO 12N53W TO 6N53W MOVING W. ASSOCIATED SCATTERED MODERATE CONVECTION IS FROM 8N TO 12N. 1027 MB HIGH PRES IS LOCATED NEAR 33N20W WITH A RIDGE AXIS EXTENDING SW ACROSS THE E ATLANTIC TO 18N44W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ LEWITSKY