000 AXNT20 KNHC 171745 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 105 PM EST TUE DEC 17 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 1715 UTC. ...ITCZ/MONSOON TROUGH... THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM THE AFRICAN COAST NEAR 08N14W TO 04N28W TO 01N50W. ISOLATED MODERATE CONVECTION IS FROM 01N-03N BETWEEN 04W-10W...AND FROM 03N-06N BETWEEN 21W-27W. WIDELY SCATTERED MODERATE CONVECTION IS FROM 04N-09N BETWEEN 09W-21W. ...DISCUSSION... GULF OF MEXICO... WATER VAPOR IMAGERY INDICATES A VERY BROAD MIDDLE TO UPPER LEVEL LONGWAVE TROUGH OVER THE EASTERN CONUS WITH A BASE OVER NORTHEASTERN GULF NEAR 27N85W THAT IS PROVIDING MOSTLY DRY AIR AND STABLE CONDITIONS ALOFT TO MUCH OF THE GULF THIS AFTERNOON. AT THE SURFACE...RIDGING FURTHER SUPPORTS THE STABILITY ALOFT ANCHORED BY A PAIR OF HIGHS...ONE A 1026 MB HIGH CENTERED ACROSS THE NW GULF NEAR 27N94W AND THE OTHER A 1027 MB HIGH CENTERED ACROSS SOUTHEASTERN LOUISIANA NEAR 30N90W. NORTHEASTERLY WINDS IN THE RANGE OF 5 TO 15 KT ARE EXPECTED TO PREVAIL THROUGH EARLY WEDNESDAY. AS THE HIGH PRESSURE AREA IS REINFORCED AND BEGINS TO SHIFT EASTWARD LATE WEDNESDAY INTO EARLY THURSDAY...E-SE FLOW WILL RE-ESTABLISH ACROSS THE NW GULF WATERS AS AN AREA LOW PRESSURE BEGINS TO DEVELOP ACROSS THE CENTRAL HIGH PLAINS OF COLORADO AND WESTERN KANSAS. SOUTHERLY RETURN FLOW IS EXPECTED TO INCREASE BY THE WEEKEND ACROSS THE WESTERN GULF AHEAD OF THE NEXT COLD FRONT EXPECTED TO EMERGE OFF THE TEXAS AND LOUISIANA COASTS EARLY SUNDAY. CARIBBEAN SEA... SOUTH-SOUTHWESTERLY FLOW ALOFT CONTINUES OVER THE WESTERN CARIBBEAN W OF 68W BETWEEN BROAD TROUGHING TO THE NORTHWEST OVER THE GULF OF MEXICO AND AN UPPER LEVEL RIDGE OVER THE CENTRAL CARIBBEAN WITH AXIS ALONG 68W. WATER VAPOR IMAGERY INDICATES AMPLE MIDDLE TO UPPER LEVEL MOISTURE ADVECTION IS OCCURRING OVER CENTRAL AMERICA AND THE NW CARIBBEAN SE OF THE SLOW MOVING TROUGHING THAT SUPPORTS A STATIONARY FRONT ANALYZED FROM WESTERN CUBA NEAR 23N80W TO 20N86W INTO THE GULF OF HONDURAS NEAR 16N87W. ISOLATED SHOWERS AND TSTMS ARE OCCURRING WITHIN 90 NM EITHER SIDE OF THE FRONT. LOW-LEVEL MOISTURE CONVERGENCE ALONG AND SOUTH OF THE FRONT...IN TANDEM WITH THE FAVORABLE MIDDLE TO UPPER LEVEL DYNAMICS IS GENERATING WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS FROM 08N-17N WEST OF A LINE FROM 08N75W TO 17N82W...WITH THE MOST INTENSE CONVECTION OCCURRING S OF 12N. FARTHER EAST...UPPER LEVEL WEST-NORTHWESTERLY FLOW E OF 68W REMAINS VERY DRY AND STABLE WITH MOSTLY FAIR SKIES AND CONDITIONS NOTED FOR HISPANIOLA...PUERTO RICO...AND THE LESSER ANTILLES. A FEW PASSING ISOLATED SHOWERS ARE POSSIBLE HOWEVER ACROSS THE EASTERN CARIBBEAN AS THESE SHOWERS REMAIN EMBEDDED WITHIN TRADE WINDS RANGING FROM 15 TO 25 KT. HISPANIOLA... CURRENTLY RELATIVELY DRY AIR AND STABLE CONDITIONS ALOFT PREVAIL WITH SATELLITE IMAGERY INDICATING ONLY LOWER LEVEL CLOUDINESS AND POSSIBLE ISOLATED SHOWERS OCCURRING ACROSS SOUTH-CENTRAL PORTIONS OF THE ISLAND INCLUDING THE ADJACENT COASTAL WATERS BETWEEN 70W-72W THIS AFTERNOON. THE OVERALL STABILITY WILL LIKELY LIMIT ANY SIGNIFICANT CONVECTION...HOWEVER AN ISOLATED SHOWER CANNOT BE RULED OUT DURING THE LATE AFTERNOON AND EARLY EVENING HOURS WITH PEAK DAYTIME HEATING AND INSTABILITY OCCURRING NEAR THE SURFACE. LOOKING AHEAD...A MOSTLY NORMAL PATTERN OF WINTER TIME TRADES IS EXPECTED TO CONTINUE ACROSS THE ISLAND WITH WINDS INCREASING SLIGHTLY THURSDAY INTO FRIDAY DUE TO A STRENGTHENING PRESSURE GRADIENT ACROSS THE REGION. ATLANTIC OCEAN... A BROAD MIDDLE TO UPPER LEVEL LONGWAVE TROUGH IS NOTED ON WATER VAPOR IMAGERY OVER THE EASTERN CONUS THAT SUPPORTS A STATIONARY FRONT ANALYZED INTO THE DISCUSSION AREA NEAR 32N60W EXTENDING SW TO THE BAHAMAS NEAR 25N77W THEN ACROSS WESTERN CUBA AND INTO THE NW CARIBBEAN SEA. ISOLATED SHOWERS AND TSTMS ARE OCCURRING WITHIN 150 NM EITHER SIDE OF THE FRONT N OF 27N AND WITHIN 90 NM EITHER SIDE OF THE FRONT S OF 27N. THE FRONT IS FORECAST TO GRADUALLY WEAKEN AND BECOME DIFFUSE BY EARLY WEDNESDAY ACROSS THE SW NORTH ATLC. FARTHER EAST...THE REMAINDER OF THE CENTRAL AND EASTERN ATLC IS UNDER THE INFLUENCE OF A LARGE AREAL SURFACE RIDGE ANCHORED BY A 1032 MB HIGH CENTERED NEAR 34N31W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN