000 AXNT20 KNHC 061137 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 705 AM EST SAT DEC 06 2014 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1115 UTC. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE E TROPICAL ATLC NEAR 13N17W TO 7N19W WHERE THE ITCZ BEGINS AND CONTINUES ALONG 4N25W TO 1N44W. SCATTERED MODERATE/STRONG CONVECTION IS WITHIN 45 NM OF LINE FROM 7N22W TO 6N25W. SCATTERED MODERATE/ ISOLATED STRONG CONVECTION COVERS THE REMAINDER OF THE AREA WITHIN 180 NM N OF THE ITCZ BETWEEN 20W-29W AND WITHIN 120 NM S OF THE ITCZ BETWEEN 26W-30W. ...DISCUSSION... GULF OF MEXICO... A NARROW UPPER TROUGH IS MOVING E OF THE LOWER MISSISSIPPI VALLEY FROM S INDIANA TO S ALABAMA THEN SW TO LAGUNA MADRE MEXICO SUPPORTING A FRONTAL BOUNDARY THAT IS MOVING THROUGH TEXAS AND WILL ENTER THE GULF LATE TONIGHT. THIS IS AMPLIFYING THE UPPER RIDGE TO THE E THAT EXTENDS FROM W CUBA JUST E OF FLORIDA AND OVER THE W ATLC. A SMALL UPPER LOW REMAINS OVER S MEXICO NEAR 17N93W AND EXTENDS TO OVER THE E BAY OF CAMPECHE. A SURFACE RIDGE IS BRIDGING A WEAK STATIONARY FRONT OVER THE FAR W ATLC AND NE FLORIDA FROM SAINT AUGUSTINE TO APALACHICOLA BAY. THE RIDGE AXIS EXTENDS FROM A 1028 MB HIGH OVER NORTH CAROLINA SW OVER THE GULF TO NEAR TAMPICO MEXICO. THIS IS LEAVING SKIES CLEAR THIS MORNING WITH SOME ISOLATED LOW LEVEL SHOWERS MOVING OVER THE E GULF FROM 23N-30N E OF 89W ACROSS FLORIDA INCLUDING THE STRAITS OF FLORIDA. THE SURFACE RIDGE WILL WEAKEN AS A WEAK COLD FRONT MOVES INTO THE NW GULF LATE TONIGHT AND WILL EXTEND FROM NAPLES FLORIDA TO BROWNSVILLE TEXAS SUN NIGHT AND DISSIPATE ACROSS MUCH OF THE GULF BY MON NIGHT AS THE REMAINDER OF THE FRONT MOVES SE THROUGH THE STRAITS OF FLORIDA. CARIBBEAN SEA... A BROAD UPPER RIDGE DOMINATES THE CARIBBEAN WITH AN UPPER RIDGE AXIS EXTENDING FROM COLOMBIA TO W CUBA. THE MONSOON TROUGH EXTENDS S OF PANAMA IN THE E PACIFIC REGION BUT CONTINUES TO GENERATE CLUSTERS OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS S OF 12N BETWEEN 75W-84W. A SURFACE TROUGH IN THE CENTRAL ATLC EXTENDS TO OVER THE LEEWARD/VIRGIN ISLANDS NEAR 18N63W. LINGERING MOISTURE WITH SCATTERED SHOWERS ARE WITHIN 90 NM OF LINE FROM 14N65W TO ACROSS THE LESSER ANTILLES NEAR DOMINICA. ISOLATED SHOWERS ARE POSSIBLE WITHIN 75 NM OF 14N BETWEEN 65W- 88W. STRONG SUBSIDENCE AND DRY STABLE AIR COVER THE CARIBBEAN N OF 17N LEAVING THIS PORTION OF THE CARIBBEAN WITH CLEAR SKIES THIS MORNING. THE W ATLC SURFACE RIDGE IS BRINGING FRESH TO OCCASIONALLY STRONG NE WINDS TO ACROSS NW AND N CENTRAL PORTIONS OF THE CARIBBEAN THROUGH TONIGHT WITH WEAKER PRESSURE GRADIENT ELSEWHERE. HISPANIOLA... SKIES OVER HISPANIOLA ARE REMARKABLY CLEAR THIS MORNING. EASTERLY FLOW ALOFT AND THE NE SURFACE FLOW WILL KEEP THE ISLAND FROM SEEING ANY SIGNIFICANT THUNDERSTORMS THROUGH MON. HOWEVER...ISOLATED LOW LEVEL FAST MOVING SHOWERS ARE ALWAYS A POSSIBILITY WITH THE NE TRADE WINDS. ATLANTIC OCEAN... THE UPPER RIDGE EXTENDS FROM THE CARIBBEAN ACROSS W CUBA INTO THE W ATLC TO BEYOND 32N75W COVERING THE AREA W OF 68W. A SURFACE RIDGE COVERS THE W ATLC ANCHORED BY A 1041 MB HIGH OVER NEWFOUNDLAND. AN UPPER TROUGH COVERS THE REMAINDER OF THE W ATLC INTO THE CENTRAL ATLC N OF 20N BETWEEN 54W-68W SUPPORTING A 1011 MB LOW NEAR 27N61W AND A SURFACE TROUGH EXTENDING N TO BEYOND 32N59W AND A SECOND SURFACE TROUGH EXTENDING S ALONG 23N61W TO OVER THE LEEWARD/VIRGIN ISLANDS NEAR 18N63W. A SECOND UPPER RIDGE IS TO THE E PROVIDING DIFFLUENCE ALOFT TO GENERATE SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS N OF 27N BETWEEN 49W-61W AND WITHIN 200 NM OF LINE FROM 27N52W ALONG 19N55W TO OVER THE LESSER ANTILLES NEAR DOMINICA. A SURFACE RIDGE COVERS THE CENTRAL INTO THE E ATLC ANCHORED BY A 1045 MB HIGH ABOUT 300 NM N OF THE AZORES. IN THE FAR E ATLC IS ANOTHER UPPER TROUGH EXTENDING ALONG 33W S INTO THE TROPICS NEAR 10N SUPPORTING A LARGE OCCLUDED FRONTAL SYSTEM N OF THE AREA WITH A COLD FRONT THAT ENTERS THE REGION NEAR 32N11W AND EXTENDS TO 29N21W. NEAR GALE FORCE WINDS ARE EXPECTED N OF 30N BETWEEN 20W- 35W. PLEASE SEE METEO FRANCE FORECAST UNDER WMO HEADER FQNT50 LFPW FOR MORE INFORMATION. THE W ATLC SURFACE RIDGE WILL SHIFT NE AHEAD OF A COLD FRONT THAT WILL MOVE INTO W ATLC TONIGHT INTO SUN AND WILL EXTEND FROM 32N71W THROUGH THE SOUTHERN BAHAMAS TO CENTRAL CUBA MON NIGHT. A NEW FRONT WILL MOVE INTO NW WATERS LATE MON. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ PAW