000 AXNT20 KNHC 120547 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT FRI JUL 12 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0515 UTC. ...SPECIAL FEATURES... A SURFACE TROUGH...THE REMNANTS OF CHANTAL...IS ANALYZED FROM CENTRAL CUBA NEAR 22N80W TO 26N79W. SUPPORTED ALOFT BY AN UPPER LEVEL LOW CENTERED OVER THE FLORIDA STRAITS NEAR 23N80W...THE ENTIRE SYNOPTIC SYSTEM IS GENERATING SCATTERED MODERATE CONVECTION ACROSS THE SW NORTH ATLC S OF 27N W OF 72W... INCLUDING PORTIONS OF INLAND CUBA. WHILE THE AREAL COVERAGE OF CONVECTION REMAINS RELATIVELY LARGE DUE TO MAXIMUM UPPER LEVEL DIFFLUENCE COVERING THE REGION...ORGANIZATION LACKS DUE TO AN INCREASED AMOUNT OF UPPER LEVEL WIND SHEAR. THE SURFACE TROUGH IS FORECAST TO DRIFT NORTHWARD OVER THE NEXT 36 TO 48 HOURS WITH A MEDIUM CHANCE OF BECOMING A TROPICAL CYCLONE. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 10N33W TO 18N33W MOVING W AT 10-15 KT. THE WAVE REMAINS EMBEDDED WITHIN THE ITCZ AXIS AND COINCIDES WITH A GLOBAL MODEL INDICATED 700 MB TROUGH AND ASSOCIATED VORTICITY MAXIMUM IN THE VICINITY OF 15N34W. TOTAL PRECIPITABLE WATER IMAGERY SHOWS A RELATIVE MOISTURE MAXIMUM FROM 10N-19N BETWEEN 27W-36W. ISOLATED MODERATE CONVECTION IS FROM 06N-13N BETWEEN 31W-37W. TROPICAL WAVE EXTENDS FROM 12N80W TO 21N80W MOVING W AT 10-15 KT. THE WAVE...THE SOUTHERN EXTENT OF ENERGY ASSOCIATED WITH THE REMNANTS OF CHANTAL...CONTINUES WESTWARD WHILE PARTIAL ENERGY HAS FRACTURED TO THE NORTH AS A SURFACE TROUGH AND NO DEFINED LOW-LEVEL CIRCULATION CENTER. PLENTY OF LOW-LEVEL MOISTURE CONVERGENCE AND MID-LEVEL VORTICITY ARE AIDING IN GENERATING WIDELY SCATTERED MODERATE CONVECTION FROM 16N-27N BETWEEN 73W- 83W...INCLUDING CUBA...THE BAHAMAS...JAMAICA...AND THE CAYMAN ISLANDS. THE WAVE IS EXPECTED TO TRACK ACROSS THE WESTERN CARIBBEAN SEA AND PORTIONS OF CENTRAL AMERICA OVER THE WEEKEND. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 12N16W TO 10N26W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 10N38W TO 06N54W. SCATTERED MODERATE CONVECTION IS FROM 08N-10N BETWEEN 17W-21W. ISOLATED MODERATE CONVECTION IS WITHIN 90 NM EITHER SIDE OF THE ITCZ AXIS BETWEEN 38W-51W. ...DISCUSSION... GULF OF MEXICO... WATER VAPOR IMAGERY INDICATES EAST-NORTHEASTERLY UPPER LEVEL FLOW NORTH OF A BROAD TROUGH AXIS EXTENDING FROM AN UPPER LEVEL LOW CENTERED OVER THE FLORIDA STRAITS NEAR 23N80W TO OVER EAST- CENTRAL MEXICO NEAR 22N100W. MOSTLY DRY AND STABLE AIR ALOFT IS NOTED OVER THE NORTHERN GULF WATERS THIS EVENING WHILE A SURFACE RIDGE ANCHORED BY A 1016 MB HIGH CENTERED NEAR 25N89W LIES BENEATH PROVIDING FOR OVERALL TRANQUIL CONDITIONS FROM 22N-28N. THE SURFACE RIDGING HAS WEAKENED INFLUENCE OVER THE NORTHERN GULF COAST WITH ISOLATED SHOWERS AND TSTMS OCCURRING N OF 28N THIS EVENING. ANOTHER WEAKNESS IN THE SURFACE RIDGE IS NOTED ACROSS THE FLORIDA STRAITS AS THE SPECIAL FEATURE...REMNANTS OF CHANTAL...BEGIN TO IMPACT THE SOUTHERN FLORIDA PENINSULA AND ADJACENT COASTAL WATERS SURROUNDING THE FLORIDA KEYS THROUGH THE OVERNIGHT HOURS. ACROSS PORTIONS OF THE SW GULF...WITHIN MOSTLY WESTERLY FLOW ALOFT ON THE SOUTHERN PERIPHERY OF THE UPPER LEVEL TROUGHING...MIDDLE TO UPPER LEVEL MOISTURE INCREASES WITH ISOLATED SHOWERS OCCURRING S OF 23W. LOOKING AHEAD...SURFACE RIDGING IS EXPECTED TO REMAIN IN PLACE ACROSS THE BASIN THROUGH EARLY NEXT WEEK WITH GENERALLY E-SE WINDS PERSISTING. CARIBBEAN SEA... THE PRIMARY FOCUS FOR THE CARIBBEAN REMAINS ON THE SOUTHERN EXTENT OF ENERGY...REMNANT ENERGY OF CHANTAL...MOVING WESTWARD AS A TROPICAL WAVE ALONG 80W IN THE WESTERN CARIBBEAN. THE TROPICAL WAVE CONTINUES GENERATING WIDELY SCATTERED SHOWERS AND TSTMS FROM 15N-22N BETWEEN 76W-83W...INCLUDING MUCH OF CUBA... JAMAICA...AND THE CAYMAN ISLANDS THIS EVENING. THE WAVE IS EXPECTED TO DRIFT WESTWARD OVER THE WEEKEND BRINGING INCREASED CHANCES OF PRECIPITATION TO THE NW CARIBBEAN AND PORTIONS OF CENTRAL AMERICA. OTHERWISE...THE MONSOON TROUGH AXIS EXTENDS ALONG 11N IN THE SW CARIBBEAN AND IS ONLY GENERATING A FEW ISOLATED SHOWERS AND TSTMS S OF 13N W OF 80W. THE REMAINDER OF THE CENTRAL AND EASTERN CARIBBEAN HAS RESUMED AN OVERALL QUIET PATTERN WITH WATER VAPOR IMAGERY INDICATING DRY AIR AND SUBSIDENCE ALOFT...ALONG WITH LIGHT NORTHEAST TO EAST TRADES. THE TRADES ARE FORECAST TO INCREASE GRADUALLY BETWEEN 65W-80W BY EARLY TUESDAY DUE TO AN INCREASE PRESSURE GRADIENT BETWEEN A CENTRAL ATLC RIDGE AND LOWER PRESSURE ACROSS THE SW CARIBBEAN AND NORTHERN SOUTH AMERICA. HISPANIOLA... CURRENTLY...MOST OF THE REMNANTS OF CHANTAL HAVE SHIFTING NW OF THE ISLAND WITH ONLY A FEW ISOLATED SHOWERS OCCURRING OVER NW PORTIONS OF THE ISLAND THIS EVENING. SURFACE RIDGING TO THE NORTH AND EAST WILL CONTINUE TO BUILD WESTWARD OVER THE NEXT 24 TO 36 HOURS AS CONDITIONS ACROSS HISPANIOLA ARE EXPECTED TO IMPROVE LATE FRIDAY INTO EARLY SATURDAY. THEREAFTER...TRADES WILL RESUME ACROSS THE REGION WITH THE MORE TYPICAL AFTERNOON SCATTERED SHOWERS AND TSTMS OCCURRING ACROSS THE ISLAND DURING THE WEEKEND INTO EARLY NEXT WEEK. ATLANTIC OCEAN... AN UPPER LEVEL LOW IS CENTERED OVER THE FLORIDA STRAITS NEAR 24N80W THAT IS PROVIDING SUPPORT FOR THE CONVECTION ASSOCIATED WITH THE SPECIAL FEATURES SURFACE TROUGH...THE REMNANTS OF CHANTAL THIS EVENING ACROSS THE EASTERN FLORIDA STRAITS AND BAHAMAS. SCATTERED SHOWERS AND TSTMS ARE OCCURRING S OF 27N W OF 72W. THIS FEATURE IS EXPECTED TO SLIP NORTHWARD OVER THE NEXT 24 TO 36 HOURS AROUND THE WESTERN PERIPHERY OF SURFACE RIDGING ACROSS THE REMAINDER OF THE SW NORTH ATLC. THE RIDGE IS ANCHORED BY A 1022 MB HIGH CENTERED NE OF BERMUDA NEAR 33N63W. FARTHER EAST...AN UPPER LEVEL LOW IS CENTERED NEAR 29N59W THAT REMAINS AT THE SOUTHWESTERN EXTENT OF A STATIONARY FRONT ANALYZED FROM 32N43W TO 31N50W TO 28N56W. MOISTURE ASSOCIATED WITH THE UPPER LEVEL LOW AND A WEAK SURFACE TROUGH ANALYZED FROM 22N55W TO 27N54W ARE GENERATING ISOLATED SHOWERS AND TSTMS FROM 25N-32N BETWEEN 53W-63W. GLOBAL MODELS INDICATE THIS UPPER LEVEL FEATURE WILL DRIFT WESTWARD ACROSS THE SW NORTH ATLC OVER THE COMING DAYS. FINALLY...THE EASTERN ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1021 MB HIGH CENTERED NEAR 31N37W. A SAHARAN AIR LAYERS CONTINUES TO BE THE OVERALL DOMINATE FEATURE PROVIDING FAIRLY STABLE CONDITIONS N OF 18N E OF 50W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN