000 AXNT20 KNHC 130545 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 105 AM EST THU DEC 13 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1115 UTC. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 07N12W TO 05N16W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 05N16W TO 05N26W TO 02N46W. SCATTERED MODERATE CONVECTION IS FROM 02N-08N BETWEEN 12W-19W...AND WITHIN 90 NM EITHER SIDE OF THE ITCZ AXIS BETWEEN 19W AND 39W. ...DISCUSSION... GULF OF MEXICO... A MIDDLE TO UPPER LEVEL SHORTWAVE TROUGH IS NOTED ON WATER VAPOR IMAGERY OVER THE SE CONUS WITH AXIS EXTENDING FROM OVER THE TENNESSEE RIVER VALLEY SOUTHWARD TO OVER THE NORTHERN FLORIDA PENINSULA. THIS TROUGHING SUPPORTS A STATIONARY FRONT ANALYZED FROM THE CENTRAL FLORIDA PENINSULA SW INTO THE GULF FROM TAMPA BAY TO 23N90W TO THE SOUTHERN MEXICO COAST NEAR 19N95W. THE FRONT HAS CONTINUED TO BECOME MORE DIFFUSE OVER THE PAST 24 HOURS WITH POSSIBLE ISOLATED SHOWERS OCCURRING WITHIN 90 NM EITHER SIDE OF THE BOUNDARY. TO THE NW OF THE FRONT...SKIES CONTINUE TO CLEAR AS THE MIDDLE TO UPPER LEVELS OF THE ATMOSPHERE REMAIN DRY AND STABLE THIS EVENING WITH A RIDGE BUILDING IN ACROSS THE SE CONUS AND WESTERN GULF WATERS. THE FRONT IS EXPECTED TO CONTINUE DISSIPATING OVER THE SE GULF LATER TODAY WITH NORTH-NORTHEASTERLY WINDS PERSISTING E OF 95W. CARIBBEAN SEA... AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED OVER THE SW CARIBBEAN NEAR 11N79W AND CONTINUES TO PROVIDE A RELATIVELY STABLE AND TRANQUIL ATMOSPHERE ACROSS MUCH OF THE BASIN THIS EVENING. WEST-NORTHWESTERLY FLOW ALOFT WITHIN DRY AIR AND SUBSIDENCE IS KEEPING SKIES FAIR WITH THE MAIN IMPACT BEING ENHANCED TRADE WINDS GENERALLY E OF 80W. THE PRESSURE GRADIENT IS EXPECTED TO MAINTAIN THESE TRADES THROUGH EARLY FRIDAY AS STRONG RIDGING OVER THE SW NORTH AND CENTRAL ATLC BEGINS TO SLOWLY ERODE AND SHIFT EASTWARD ON THURSDAY. OTHERWISE...A FEW PASSING ISOLATED SHOWERS ARE NOTED ON SATELLITE IMAGERY FROM 13N-18N BETWEEN 75W-82W...AND ACROSS PORTIONS OF THE LEEWARD ISLANDS N OF 15N E OF 65W. ATLANTIC OCEAN... A MIDDLE TO UPPER LEVEL SHORTWAVE TROUGH IS PROGRESSING EAST- NORTHEASTWARD OVER THE SE CONUS AND SUPPORTS A WEAK 1015 MB LOW CENTERED NEAR 32N77W. A STATIONARY FRONT EXTENDS SW FROM THE LOW CENTER TO THE FLORIDA PENINSULA NEAR CAPE CANAVERAL WITH WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS OCCURRING N OF 27N W OF 72W. THE REMAINDER OF THE SW NORTH ATLC AND CENTRAL ATLC IS UNDER THE INFLUENCE OF A RIDGE ANCHORED BY A 1027 MB HIGH CENTERED NEAR 31N55W. A COUPLE AREAS OF LOW-LEVEL MOISTURE AND EMBEDDED LOW-TOPPED ISOLATED SHOWERS ARE MOVING WESTWARD ON THE SOUTHWESTERN PERIPHERY OF THE RIDGE IMPACTING THE LEEWARD ISLANDS AND AREAS S OF 22N BETWEEN 58W-65W...AND AN AREA EAST OF THE TURKS AND CAICOS ISLANDS FROM 19N-25N BETWEEN 67W-72W. OTHERWISE...A MIDDLE TO UPPER LEVEL LOW IS CENTERED OVER THE CENTRAL ATLC NEAR 20N50W THAT CONTINUES TO SUPPORT A SURFACE TROUGH ANALYZED FROM 11N52W TO 17N46W. LOW-LEVEL MOISTURE CONVERGENCE IN THE VICINITY OF THE SURFACE TROUGH ALONG WITH MAXIMIZED MIDDLE TO UPPER LEVEL DIFFLUENCE EAST OF THE UPPER LEVEL LOW IS GENERATING A LARGE AREA OF SCATTERED SHOWERS AND ISOLATED TSTMS FROM 09N-24N BETWEEN 35W-51W. TO THE NORTH OF THIS AREA...SURFACE RIDGING DOMINATES ANCHORED BY A 1028 MB HIGH CENTERED NEAR 31N39W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN