000 AXNT20 KNHC 071707 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 105 PM EST THU NOV 07 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 1645 UTC. ...SPECIAL FEATURES... A GALE WARNING GOES INTO EFFECT FOR THE SW GULF OF MEXICO AT 07/1800 UTC. THIS GALE IS ASSOCIATED WITH THE COLD FRONT CURRENTLY ANALYZED ACROSS THE NORTH-CENTRAL AND WESTERN GULF. SEE THE HIGH SEAS FORECAST UNDER AWIPS/WMO HEADERS MIAHSFAT2/FZNT02 KNHC FOR MORE DETAILS. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 13N17W TO 12N22W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 04N26W TO 04N33W TO 07N41W. A SURFACE TROUGH IS ANALYZED AT THE WESTERN EXTENT OF THE AXIS FROM 05N44W TO 12N42W. SCATTERED MODERATE CONVECTION IS FROM 01N-12N BETWEEN 25W-44W. ISOLATED MODERATE CONVECTION IS FROM 03N-07N BETWEEN 08W-17W...AND FROM 08N-13N BETWEEN 44W-53W. ...DISCUSSION... GULF OF MEXICO... WATER VAPOR IMAGERY INDICATES A BROAD LONGWAVE TROUGH OVER THE GREAT LAKES AND OHIO RIVER VALLEY WITH A TROUGH AXIS EXTENDING S- SW TO OVER THE LOWER MISSISSIPPI RIVER VALLEY TO A BASE OVER THE NW GULF WATERS. THIS TROUGHING SUPPORTS A COLD FRONT ANALYZED FROM MOBILE BAY NEAR 31N88W SW TO THE MEXICO COAST NEAR 25N97W. WITH MOST OF THE UPPER LEVEL DYNAMICS REMAINING N OF 36N...THE FRONT LACKS ANY SIGNIFICANT DEEP CONVECTION...HOWEVER OVERCAST SKIES AND A FEW AREAS OF ISOLATED SHOWERS ARE NOTED ON SATELLITE IMAGERY WITHIN 75 NM EITHER SIDE OF THE FRONT. THE MOST IMPORTANT IMPACT ASSOCIATED WITH THE FRONT IS THE SPECIAL FEATURE HIGHLIGHTING A DEVELOPING GALE SITUATION ACROSS A PORTION OF THE WESTERN GULF WATERS BEGINNING THIS AFTERNOON AND REMAINING VALID THROUGH EARLY FRIDAY. A PAIR OF SURFACE TROUGHS ARE ANALYZED IN ADVANCE OF THE COLD FRONT...ONE ANALYZED ACROSS THE CENTRAL GULF WATERS FROM 30N88W TO 24N92W AND THE OTHER SURFACE TROUGH EXTENDING SOUTHWARD FROM THE COLD FRONT NEAR 25N96W TO 20N95W. ISOLATED SHOWERS ARE OCCURRING WITHIN 60 NM EITHER SIDE OF THE EASTERN-MOST BOUNDARY...WHILE ISOLATED SHOWERS AND TSTMS ARE OCCURRING WITHIN 90 NM WEST OF THE WESTERN- MOST BOUNDARY. FINALLY...A BROAD UPPER LEVEL ANTICYCLONE IS CENTERED OVER THE NW CARIBBEAN SEA NEAR 21N84W THAT IS PROVIDING SOUTH-SOUTHWESTERLY FLOW ALOFT ACROSS THE MAJORITY OF THE GULF E OF 94W. MARGINAL UPPER LEVEL DIFFLUENCE AND THE CLOSE PROXIMITY OF A SURFACE TROUGH AXIS ANALYZED ACROSS THE NW CARIBBEAN SEA AND NE YUCATAN PENINSULA IS PROVIDING FOR WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS S OF 25N BETWEEN 83W-88W. BY EARLY FRIDAY...WITH FRONTAL PASSAGE HAVING OCCURRING OVER MUCH OF THE GULF...NORTHEAST WINDS WILL DOMINATE GENERALLY IN THE RANGE OF 20 TO 30 KT AND GRADUALLY DECREASE THROUGH THE DURATION OF THE UPCOMING WEEKEND. CARIBBEAN SEA... AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED OVER THE NW CARIBBEAN NEAR 21N84W THAT IS PROVIDING AN OVERALL DIFFLUENT ENVIRONMENT ALOFT FOR THE NW CARIBBEAN AND PORTIONS OF CENTRAL AMERICA THIS AFTERNOON. WHILE THE DIFFLUENCE SUPPORTS ONGOING CONVECTION...A SURFACE TROUGH IS ANALYZED FROM 15N83W TO 22N87W AND IS PROVIDING FOCUS FOR SCATTERED SHOWERS AND ISOLATED TSTMS OCCURRING N OF 16N W OF 81W...INCLUDING THE GULF OF HONDURAS. FURTHERMORE...A LINE OF ISOLATED SHOWERS AND TSTMS IS NOTED WITHIN 60 NM EITHER SIDE OF A LINE FROM 11N84W TO 16N84W MOVING INLAND ACROSS EASTERN HONDURAS AND NICARAGUA THIS AFTERNOON. THE REMAINDER OF THE CENTRAL AND EASTERN CARIBBEAN IS UNDER THE INFLUENCE OF RELATIVELY DRIER NORTH-NORTHEASTERLY FLOW ALOFT ON THE EASTERN PERIPHERY OF THE UPPER LEVEL ANTICYCLONE. THE OVERALL STABILITY IS RESULTING IN MOSTLY FAIR CONDITIONS AND MOSTLY CLEAR SKIES E OF 80W...WITH THE ONLY EXCEPTION BEING AN AREA OF ISOLATED SHOWERS AND TSTMS S OF 13N BETWEEN 75W-80W. TRADES ARE EXPECTED TO PERSIST GENERALLY IN THE RANGE OF 10 TO 20 KT THROUGH LATE SATURDAY WHEN THE PRESSURE GRADIENT ACROSS THE BASIN WILL BEGIN TO GRADUALLY STRENGTHEN DUE TO STRONG HIGH PRESSURE BUILDING TO THE NORTH ACROSS THE SW NORTH ATLC. TRADES ARE FORECAST FRESH TO STRONG THROUGH THE FRONT PORTION OF NEXT WEEK. HISPANIOLA... CURRENTLY CONDITIONS ACROSS THE ISLAND ARE RELATIVELY TRANQUIL DUE TO DRY NE WINDS ALOFT AND STRONG SUBSIDENCE IN PLACE. WHILE NO SIGNIFICANT DEEP CONVECTION IS ANTICIPATED THROUGH THE AFTERNOON AND EVENING HOURS...A FEW ISOLATED SHOWERS ARE POSSIBLE AS WEAK LOW-LEVEL MOISTURE CONVERGENCE AND OROGRAPHIC LIFT WILL INCREASE CLOUDINESS AND THE PROBABILITY OF PRECIPITATION. ATLANTIC OCEAN... AN UPPER LEVEL ANTICYCLONE ANCHORED OVER THE NW CARIBBEAN SEA EXTENDS AN UPPER LEVEL RIDGE AXIS NE TO BEYOND 32N70W. MUCH OF THE SW NORTH ATLC IS UNDER THE INFLUENCE OF THIS RIDGING WITH A NARROW STREAM OF MOISTURE NOTED ON WATER VAPOR IMAGERY EXTENDING FROM THE NW CARIBBEAN SEA THROUGH THE SE GULF OF MEXICO AND INTO FAR WESTERN PORTIONS OF THE SW NORTH ATLC. A WEAKNESS WITHIN THE RIDGE ALOFT REFLECTS TO THE SURFACE AS A SURFACE TROUGH ANALYZED FROM THE CENTRAL BAHAMAS NEAR 25N77W TO 30N79W AND INTO A 1014 MB LOW CENTERED ALONG THE NORTH CAROLINA COAST NEAR 35N77W. MOST OF THE MOISTURE MANIFESTS ITSELF AS CLOUDINESS W OF 76W... HOWEVER A FEW ISOLATED SHOWERS ARE OCCURRING N OF 26N W OF 75W TO THE FLORIDA PENINSULA COASTLINE. THE REMAINDER OF THE SW NORTH ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE AXIS EXTENDING FROM BEYOND 32N65W SW TO 27N74W. FARTHER EAST...A MIDDLE TO UPPER LEVEL LOW IS CENTERED NEAR 31N53W WITH A TROUGH AXIS EXTENDING S-SW TO A BASE NEAR 17N58W. THE UPPER LEVEL TROUGH SUPPORTS A 1014 MB LOW CENTERED NEAR 31N47W AND ASSOCIATED WARM FRONT EXTENDING E-NE TO BEYOND 32N46W. A STATIONARY FRONT EXTENDS SW FROM THE LOW CENTER TO 29N53W AND BECOMES A SHEAR LINE TO 27N63W. MAXIMUM MIDDLE TO UPPER LEVEL DIFFLUENCE IS OCCURRING EAST OF THE UPPER LEVEL TROUGH AXIS AND INDUCES TROUGHING AS THE SURFACE EXTENDING TO THE SW OF THE LOW CENTER. A PAIR OF SURFACE TROUGHS ARE NOTED IN THE VICINITY OF A LINE FROM 30N48W TO 17N60W AND ARE PROVIDING FOCUS FOR SCATTERED SHOWERS AND TSTMS OCCURRING WITHIN 240 NM EITHER SIDE OF A LINE FROM 32N44W TO 18N58W. OTHERWISE...THE REMAINDER OF THE EASTERN ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1025 MB HIGH CENTERED NEAR 30N27W AND A 1026 MB HIGH CENTERED NEAR 32N19W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN