000 AXNT20 KNHC 271745 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT TUE AUG 27 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. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM A 1014 MB LOW CENTERED NEAR 10N31W TO 19N29W MOVING W AT 10-15 KT. AS EXPECTED FROM YESTERDAY AT THIS TIME...THE SOUTHERN VORTICITY MAXIMUM ALONG THE WAVE AXIS BECAME THE DOMINATE FEATURE AND IS CURRENTLY A WEAK AND BROAD CYCLONIC MONSOONAL GYRE WITH INFLUENCE FROM 08N-16N BETWEEN 23W-38W. AS THE LOW-LEVEL ENERGY CONTINUES TO PROPAGATE WESTWARD AS A WHOLE...UPPER LEVEL SOUTHWESTERLIES TO THE NORTHWEST OF THE WAVE AXIS WILL SLOWLY FRACTURE ENERGY AWAY FROM THE WAVE TO THE NORTH OVER THE NEXT 24 TO 48 HOURS. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS WITHIN 120 NM EITHER SIDE OF A LINE FROM 13N31W TO 08N37W. TROPICAL WAVE EXTENDS FROM 13N48W TO 23N44W MOVING W AT 10-15 KT. THE WAVE REMAINS EMBEDDED WITHIN A MAXIMUM OF TOTAL PRECIPITABLE WATER EXTENDING NORTHWARD FROM THE MONSOON TROUGH REGION FROM 11N-22N BETWEEN 39W-50W AND COINCIDES WITH A 700 MB TROUGH AXIS WITH A RELATIVE VORTICITY MAXIMUM CENTERED IN THE VICINITY OF 20N46W ALONG THE WAVE AXIS. THE WAVE LACKS ANY SIGNIFICANT DEEP CONVECTION AT THIS TIME DUE TO THE PRESENCE OF THE SAHARAN AIR LAYER ACROSS MUCH OF THE CENTRAL ATLC. TROPICAL WAVE EXTENDS FROM 11N81W TO 20N83W MOVING W AT 10-15 KT. THE WAVE CONTINUES TO BE EMBEDDED WITHIN BROAD LOW-LEVEL TROUGHING ACROSS THE WESTERN CARIBBEAN SEA. TOTAL PRECIPITABLE WATER IMAGERY INDICATES THE WAVE LIES WITHIN A RELATIVELY MOIST ENVIRONMENT W OF 80W WITH SCATTERED MODERATE CONVECTION FROM 11N- 18N BETWEEN 81W-85W. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM 12N17W TO 10N31W TO 12N46W TO A 1013 MB LOW NEAR 11N54W TO 09N56W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 09N56W TO 11N64W AND THE MONSOON TROUGH AXIS RESUMES NEAR 11N64W TO 11N70W TO 10N83W. WIDELY SCATTERED MODERATE CONVECTION IS FROM 06N-10N BETWEEN 14W-22W...AND WITHIN 60 NM OF THE 1013 MB LOW CENTER NEAR 11N54W. SCATTERED MODERATE TO STRONG CONVECTION IS ALSO ENHANCED BY THE MONSOON TROUGH AXIS OVER THE SW CARIBBEAN SEA FROM 08N-13N BETWEEN 74W-82W. THIS CONVECTION IS LIKELY ENHANCED DUE TO AN UPPER LEVEL DIFFLUENT ENVIRONMENT OVER THE WESTERN CARIBBEAN AT THIS TIME. ...DISCUSSION... GULF OF MEXICO... WATER VAPOR IMAGERY INDICATES A MIDDLE TO UPPER LEVEL LOW IS CENTERED OVER THE STRAITS OF FLORIDA NEAR 23N81W THAT IS PROVIDING THE SE GULF AND SOUTHERN FLORIDA PENINSULA WITH SCATTERED SHOWERS AND WIDELY SCATTERED TSTMS S OF 28N E OF 84W. AS OF 27/1500 UTC A WEAK SURFACE TROUGH EXTENDS NORTHWEST OF THIS CONVECTION PRECIPITATION FROM 25N85W TO 29N85W. AT THIS TIME THE SURFACE TROUGH REMAINS FAIRLY BENIGN AS THE REMAINDER OF THE GULF BASIN IS UNDER THE INFLUENCE OF NORTHERLY FLOW ALOFT W OF 84W. THE NORTHERLY FLOW IS PROVIDING A STABLE ENVIRONMENT AND SUPPORTING A BROAD SURFACE RIDGE EXTENDING FROM LOUISIANA SOUTHWARD TO THE BAY OF CAMPECHE WITH OVERALL PARTLY CLOUDY SKIES AND FAIR CONDITIONS THIS AFTERNOON. LOOKING AHEAD...WITH A SURFACE RIDGE ANCHORED TO THE NORTH OVER THE SE CONUS...E-SE WINDS ARE FORECAST TO PERSIST THROUGH LATE WEDNESDAY. DURING THAT TIME...THE SURFACE RIDGING WILL SLOWLY SHIFT SOUTHWARD INTO THE GULF BY LATE THURSDAY INTO FRIDAY AND REMAIN NEARLY STATIONARY WITH A RIDGE AXIS ALONG 27N. CARIBBEAN SEA... THE BASE OF A MIDDLE TO UPPER LEVEL LOW CENTERED OVER THE FLORIDA STRAITS NEAR 23N81W REMAINS OVER THE NW CARIBBEAN WITH THE BASE OF THE TROUGH NEAR 17N84W. MIDDLE TO UPPER LEVEL DIFFLUENCE ALONG WITH THE PRESENCE OF A TROPICAL WAVE ALONG 83W IS PROVIDING FOR INCREASED ATMOSPHERIC LIFT AND GENERATING SCATTERED SHOWERS AND TSTMS FROM 11N-18N BETWEEN 81W-85W...WITH ISOLATED SHOWERS AND TSTMS ELSEWHERE S OF 21N W OF 80W. TO THE SOUTHEAST OF THE TROPICAL WAVE...A LARGE COMPLEX OF SCATTERED SHOWERS AND TSTMS IS OCCURRING IN THE VICINITY OF THE MONSOON TROUGH FROM 08N-13N BETWEEN 74W-81W. THIS CONVECTION IS LIKELY ENHANCED DUE TO A FAVORABLE UPPER LEVEL DIFFLUENT ENVIRONMENT S OF 15N BETWEEN 72W-84W. FARTHER EAST...AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED OVER THE EASTERN CARIBBEAN NEAR 16N70W. WHILE WATER VAPOR IMAGERY INDICATES RELATIVELY DRIER AIR ALOFT WITHIN A CORRIDOR FROM 20N60W TO OVER THE ABC ISLANDS NEAR 12N69W...A SURFACE TROUGH IS ANALYZED TO THE NORTH OF THIS CORRIDOR FROM 15N69W TO 21N68W. SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING FROM 14N-23N BETWEEN 65W-72W... INCLUDING PUERTO RICO...THE MONA PASSAGE...AND PORTIONS OF EASTERN HISPANIOLA. THE OTHER AREA OF SIGNIFICANT SCATTERED SHOWERS AND TSTMS ARE OCCURRING OVER THE WINDWARD ISLANDS FROM 10N-15N BETWEEN 58W-63W. FINALLY...EASTERLY TRADES PERSIST GENERALLY 20 KT OR LESS AND ARE FORECAST TO GRADUALLY INCREASE BY EARLY THURSDAY AS THE OVERALL PRESSURE GRADIENT STRENGTHENS BETWEEN LOWER PRESSURE ACROSS SOUTH AMERICA AND A SW NORTH ATLC SURFACE RIDGE ALONG 26N/27N. HISPANIOLA... MOIST SOUTHWESTERLY FLOW ALOFT IS OVER HISPANIOLA THIS AFTERNOON AND IS PROVIDING FOR AN OVERALL DIFFLUENT ATMOSPHERE FOR THE ISLAND. MOVING WESTWARD BENEATH THIS FLOW IS SURFACE TROUGH ANALYZED FROM 15N65W TO 22N68W. LOW-LEVEL MOISTURE IS FOCUSED ON BOTH SIDES OF THE SURFACE TROUGH BETWEEN 65W-71W WHICH IS ALREADY PROVIDING THE ISLAND WITH ISOLATED SHOWERS E OF 71W. MOISTURE AND PRECIPITATION IS EXPECTED TO INCREASE AS THE SURFACE TROUGH MOVES WEST OVER THE NEXT 24 TO 48 HOURS. PEAK DAYTIME HEATING AND INSTABILITY WILL LIKELY GENERATE MORE INTENSE SHOWERS AND TSTMS THIS AFTERNOON AND EVENING WITH ANY ACTIVITY DIMINISHING BEYOND THE LATE EVENING HOURS. ATLANTIC OCEAN... A MIDDLE TO UPPER LEVEL TROUGH AXIS EXTENDS INTO THE DISCUSSION AREA NEAR 32N65W IN THE SW NORTH ATLC AND EXTENDS SOUTHWEST TO 28N74W AND INTO A MIDDLE TO UPPER LEVEL LOW CENTERED OVER THE FLORIDA STRAITS NEAR 23N81W. THIS TROUGHING ALOFT SUPPORTS A DISSIPATING STATIONARY FRONT ANALYZED FROM 31N62W TO 29NN70W TO 28N76W THEN CONTINUES SW AS A SURFACE TROUGH TO 24N80W. WATER VAPOR IMAGERY INDICATES THAT THE UPPER LEVEL DYNAMICS ARE MORE CONCENTRATED OVER THE FLORIDA STRAITS AND THIS IS WHERE SCATTERED SHOWERS AND TSTMS ARE OCCURRING FROM 23N-28N BETWEEN 77W-83W. TO THE NORTHEAST CLOSER TO THE STATIONARY FRONT...LOW- LEVEL MOISTURE CONVERGENCE ALONG AND SOUTH OF THE BOUNDARY CONTINUES TO PRODUCE ISOLATED SHOWERS AND TSTMS N OF 27N BETWEEN 58W-68W. TO THE SOUTHEAST...A SURFACE TROUGH EXTENDS FROM THE NORTH-CENTRAL CARIBBEAN SEA NEAR 15N69W TO 22N68W WITH LOW-LEVEL MOISTURE CONVERGENCE AND INSTABILITY GENERATING SCATTERED SHOWERS AND TSTMS FROM 15N-23N BETWEEN 65W-70W. ASIDE FROM THE TWO TROPICAL WAVES PROGRESSING WESTWARD...THE REMAINDER OF THE CENTRAL AND EASTERN ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1031 MB HIGH CENTERED NORTH OF THE AZORES NEAR 43N26W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN