000 AXNT20 KNHC 141735 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT WED AUG 14 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. ...SPECIAL FEATURES... TROPICAL WAVE EXTENDS FROM 13N21W TO 18N20W MOVING W AT 10-15 KT. THE WAVE REMAINS EMBEDDED WITHIN THE MONSOON TROUGH WITH A LOW-LEVEL CYCLONIC CIRCULATION FOCUSED ON A 1009 MB LOW CENTERED NEAR 13N21W. AN EARLY MORNING ASCAT PASS AROUND 14/1122 UTC INDICATED THE PRESENCE OF THE LOW-LEVEL CIRCULATION AND THE WAVE AXIS WITH 20-30 KT SOUTH-SOUTHWESTERLY WINDS WITHIN 210 NM OF THE SE SEMICIRCLE OF THE LOW CENTER. SCATTERED MODERATE CONVECTION IS FROM 09N-14N BETWEEN 18W-30W. TROPICAL WAVE EXTENDS FROM 13N83W TO 23N83W MOVING W-NW AT 10-15 KT. THE WAVE CORRESPONDS WITH BROAD CYCLONIC FLOW ACROSS THE NW CARIBBEAN FOCUSED IN THE VICINITY OF A 1009 MB LOW CENTERED NEAR 17N83W. FURTHER DEVELOPMENT AND ORGANIZATION OF CONVECTION ASSOCIATED WITH THE WAVE IS EXPECTED OVER THE NEXT FEW DAYS AS THE SYSTEM MOVES TOWARD THE YUCATAN CHANNEL AND PENINSULA AND EVENTUALLY INTO THE GULF OF MEXICO. SCATTERED MODERATE CONVECTION IS OCCURRING FROM 12N-23N BETWEEN 80W-87W. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 12N43W TO 19N39W MOVING W AT 15 KT. THE WAVE COINCIDES WITH A BROAD LOW-LEVEL CYCLONIC FLOW THAT REMAINS EMBEDDED WITHIN THE MONSOON TROUGH AXIS BETWEEN 35W-50W. TOTAL PRECIPITABLE WATER IMAGERY INDICATES MAXIMUM VALUES FROM 08N-18N BETWEEN 32W-45W. CONVECTION REMAINS LARGELY SUPPRESSED DUE TO THE EXPANSIVE SAHARAN AIR LAYER COVERING MUCH OF THE CENTRAL AND EASTERN ATLC. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 18N16W TO 13N21W TO 12N24W TO 14N36W TO 08N52W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 08N52W TO 09N64W. SCATTERED MODERATE CONVECTION IS FROM 09N-14N BETWEEN 18W-30W...FROM 09N- 12N BETWEEN 34W-40W...AND FROM 09N-13N BETWEEN 44W-51W. WIDELY SCATTERED MODERATE CONVECTION IS WITHIN 150 NM N OF THE AXIS BETWEEN 57W-64W. ...DISCUSSION... GULF OF MEXICO... NORTHEASTERLY UPPER LEVEL FLOW IS NOTED ON WATER VAPOR IMAGERY OVER THE GULF THIS AFTERNOON BETWEEN AN UPPER LEVEL ANTICYCLONIC CIRCULATION CENTERED OVER NORTHERN MEXICO NEAR 30N107W AND A VERY NARROW UPPER LEVEL TROUGH AXIS EXTENDING FROM OVER THE NE GULF NEAR 29N83W SW TO AN UPPER LEVEL LOW OVER INLAND EAST- CENTRAL MEXICO NEAR 19N99W. OVERALL...THIS IS PROVIDING THE GULF WITH A MODERATELY DRY AIRMASS ALOFT WITH ONLY A FEW AREAS OF ONGOING CONVECTION NOTED ON SATELLITE IMAGERY AT THIS TIME. SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING ACROSS THE NORTH-CENTRAL GULF COAST N OF 29N BETWEEN 86W-92W...AND ISOLATED SHOWERS ARE OCCURRING ACROSS THE SW GULF S OF 21N BETWEEN 93W- 97W. OTHERWISE...A SURFACE RIDGE ANCHORED BY A 1016 MB HIGH CENTERED NEAR 27N91W AT 14/1500 UTC EXTENDS A RIDGE AXIS EASTWARD ALONG 27N INTO THE SW NORTH ATLC REGION AND SW TO THE MEXICO COAST NEAR 22N98W. LIGHT AND VARIABLE WINDS IN THE RANGE OF 5-10 KT ARE EXPECTED TO GRADUALLY BECOME MORE NORTHEASTERLY BY LATE WEDNESDAY AS A TROPICAL WAVE AND ASSOCIATED LOW PRESSURE CENTER MOVES INTO THE YUCATAN CHANNEL REGION AND ACROSS THE YUCATAN PENINSULA THROUGH THURSDAY. GLOBAL MODELS CONTINUE TO DIFFER SLIGHTLY ON EXACT TRACK OF THIS FEATURE...HOWEVER ONGOING CONVECTION AND PRECIPITATION OCCURRING ACROSS THE WESTERN CARIBBEAN WILL SHIFT INTO THE GULF THIS WEEKEND. CARIBBEAN SEA... AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED NEAR 20N80W THAT IS PROVIDING A BROAD AREA OF MIDDLE TO UPPER DIFFLUENCE OVER THE NW CARIBBEAN. AT THE SURFACE...THE SPECIAL FEATURES TROPICAL WAVE AND ASSOCIATED LOW PRESSURE AREA IS LOCATED BENEATH THIS FEATURE AND MOVING AROUND THE SOUTHWESTERN PERIPHERY OF THE RIDGE. NUMEROUS SHOWERS AND SCATTERED TSTMS ARE OCCURRING FROM 12N-23N BETWEEN 80W-88W. THIS AREA OF PRECIPITATION AND CONVECTION IS FORECAST TO MOVE W-NW OVER THE NEXT 48 HOURS IMPACTING THE GULF OF HONDURAS...BELIZE...NORTHERN GUATEMALA...AND THE YUCATAN PENINSULA AND CHANNEL. FARTHER SOUTH...THE MONSOON TROUGH AXIS EXTENDS ACROSS PANAMA AND COSTA RICA THEN INTO THE EAST PACIFIC REGION WITH ONLY A FEW ISOLATED SHOWERS AND TSTMS OCCURRING FROM 08N-11N BETWEEN 81W-84W. FINALLY...NORTHERLY UPPER LEVEL FLOW DOMINATES OVER THE CENTRAL CARIBBEAN AND IS PROVIDING RELATIVELY STABLE AND FAIR CONDITIONS E OF 75W THIS AFTERNOON. ONE EXCEPTION TO THIS IS A FEW ISOLATED SHOWERS AND TSTMS OCCURRING OVER THE SE CARIBBEAN S OF 12N BETWEEN 60W-68W WHICH IS LARGELY ASSOCIATED WITH THE ITCZ AXIS ANALYZED ACROSS NE VENEZUELA. HISPANIOLA... CURRENTLY LOW-LEVEL MOISTURE AND ISOLATED SHOWERS ARE OCCURRING IN THE VICINITY OF THE SOUTHERN COASTLINE WITH E-SE SURFACE WINDS PERSISTING AND CONTINUED ADVECTION OF LOW-LEVEL MOISTURE. THROUGH THE REST OF THE AFTERNOON AND EVENING HOURS...PEAK HEATING AND INSTABILITY WILL OCCUR AND PROVIDE THE OPPORTUNITY FOR SCATTERED SHOWERS AND TSTMS. OTHERWISE...LOOKING AHEAD OVER THE NEXT FEW DAYS...THE SAN JUAN PUERTO RICO 14/1200 UTC UPPER AIR SOUNDING INDICATED THE PRESENCE OF THE SAHARAN AIR LAYER FROM 850 MB UP TO ROUGHLY 650 MB. THIS AIR LAYER WILL CONTINUE TO IMPACT THE EASTERN AND CENTRAL CARIBBEAN THROUGH THE WEEKEND HELPING TO LIMIT OVERALL COVERAGE OF CONVECTION WHILE ALSO PROVIDING GENERALLY HAZY CONDITIONS. ATLANTIC OCEAN... A MIDDLE TO UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED NEAR 31N72W THAT INFLUENCES A LARGE PORTION OF THE SW NORTH ATLC W OF 70W THIS AFTERNOON. THE RIDGING ALOFT CONTINUES TO SUPPORT A SURFACE RIDGE OF HIGH PRESSURE EXTENDING FROM 28N70W WESTWARD INTO THE NORTHERN GULF OF MEXICO ALONG 27N. MOSTLY FAIR SKIES AND CONDITIONS ACCOMPANY THIS FEATURE AS WATER VAPOR IMAGERY INDICATES AN AREA OF MODERATE DRY AIR AND SUBSIDENCE STRETCHING FROM N OF THE BAHAMAS TO OFFSHORE OF THE CAROLINAS. S OF THE BAHAMAS IN THE FLORIDA STRAITS...ISOLATED SHOWERS AND TSTMS ARE OCCURRING AS MOISTURE FROM THE TROPICAL WAVE LOCATED ACROSS THE WESTERN CARIBBEAN ADVECTS NORTHEAST. FARTHER EAST ACROSS THE CENTRAL ATLC...AN UPPER LEVEL LOW IS CENTERED NEAR 28N63W AND SUPPORTS A BROAD AREA OF WIDELY SCATTERED SHOWERS AND TSTMS FROM 23N-32N BETWEEN 59W-70W. OTHERWISE...FAIRLY BENIGN CONDITIONS ARE NOTED ON SATELLITE IMAGERY E OF 55W AS A SURFACE RIDGE ANCHORED BY A 1026 MB HIGH CENTERED NEAR 34N44W DOMINATES THE OVERALL PATTERN. ASIDE FROM THE TROPICAL WAVES DISCUSSED IN DETAIL ABOVE...AN AREA OF SAHARAN DUST IS LOCATED GENERALLY N OF 15N E OF 58W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN