000 AXNT20 KNHC 151805 RRA TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT WED JUL 15 2015 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 1745 UTC. ...TROPICAL WAVES... A TROPICAL WAVE IS ENTERING THE CENTRAL ATLC. ITS AXIS IS APPROXIMATELY ALONG 31W AND MOVES W AT NEARLY 5-10 KT PER DAY. SSMI TPW IMAGERY INDICATE THE WAVE IS EMBEDDED IN A DEEP MOIST ENVIRONMENT E OF ITS AXIS AND A MODERATE MOIST ENVIRONMENT AHEAD OF IT. ENHANCEMENTS OF METEOSAT IMAGERY SHOW SAHARAN DRY AIR AND DUST ENGULFING THE WAVE. SCATTERED MODERATE CONVECTION IS FROM 07N TO 12N BETWEEN 24W AND 34W BEING SUPPORTED BY MIDDLE TO UPPER LEVEL DIVERGENCE. A TROPICAL WAVE IS E OF THE LESSER ANTILLES WITH AXIS APPROXIMATELY ALONG 57W...MOVING W AT 20 KT PER DAY. SSMI TPW AND ENHANCEMENTS OF METEOSAT IMAGERY INDICATE DRY AIR ENTRAINMENT TO THE WAVE ENVIRONMENT WHICH IS HINDERING CONVECTION. DUST IS ALSO PRESENT IN THE WAVE ENVIRONMENT AS OBSERVED IN SATELLITE IMAGERY AND IS BEING REPORTED THROUGH THE LESSER ANTILLES. A TROPICAL WAVE IS OVER THE CENTRAL CARIBBEAN WITH AXIS APPROXIMATELY ALONG 75W...MOVING W AT 15 KT. SSMI TPW IMAGERY INDICATE THE WAVE IS EMBEDDED IN A MODERATE MOIST ENVIRONMENT. DIVERGENT FLOW AHEAD OF THE WAVE IN THE MIDDLE LEVELS SUPPORT SCATTERED MODERATE CONVECTION AND TSTMS FROM 15N TO 16N BETWEEN 76W AND 79W. STRONG DEEP LAYER WIND SHEAR HINDER CONVECTION ELSEWHERE. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH ENTERS THE ATLANTIC OCEAN THROUGH GUINEA BISSAU NEAR 12N17W CONTINUING TO 11N20W. THE ITCZ EXTENDS FROM THAT POINT TO 10N29W THEN RESUMES W OF A TROPICAL WAVE NEAR 09N33W TO 06N47W TO 07N59W. ASIDE FROM THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVES...SCATTERED MODERATE CONVECTION AND ISOLATED TSTMS ARE OBSERVED FROM 05N TO 12N E OF 24W AND FROM 04N TO 11N BETWEEN 38W AND 55W. ...DISCUSSION... GULF OF MEXICO... A BROAD RIDGE COVERING GREAT PORTIONS OF THE ATLC BASIN EXTENDS AN AXIS SW ACROSS THE CENTRAL AND SOUTHERN FLORIDA PENINSULA AND THE SE GULF OF MEXICO. ALOFT...AN UPPER LOW IS OBSERVED CENTERED OVER SOUTHERN MEXICO SUPPORTING A SURFACE TROUGH OVER THE BAY OF CAMPECHE FROM 22N92W TO 17N92W...LACKING CONVECTION. MIDDLE TO UPPER LEVEL RIDGING DOMINATES ACROSS THE BASIN EXCEPT OVER THE NE GULF WHERE THE BASE OF A MIDDLE LEVEL TROUGH ALONG THE EASTERN CONUS AND SEABOARD GENERATES DIFFLUENT FLOW. TROUGHING ALOFT SUPPORT A SURFACE TROUGH EXTENDING ACROSS NORTHERN FLORIDA TO 29N83W TO 29N87W AND SCATTERED HEAVY SHOWERS AND TSTMS FROM 28N TO 30N E OF 87W BEING FUELED BY MOISTURE INFLOW FROM THE CARIBBEAN. WINDS ARE MAINLY FROM THE S IN THE RANGE OF 5 TO 10 KT...EXCEPT IN THE NE GULF N OF 27N WHERE WIND FLOW IS FROM THE WEST. SURFACE RIDGING WILL BE THE DOMINANT FEATURE DURING THE NEXT THREE DAYS. CARIBBEAN SEA... A TROPICAL WAVE IS OVER THE CENTRAL CARIBBEAN ASSOCIATED WITH A BROAD MODERATE AIRMASS THAT EXTENDS ACROSS THE WESTERN BASIN INTO THE GULF OF MEXICO. HOWEVER STRONG DEEP LAYER WIND SHEAR INHIBITS CONVECTION FOR THE MOST PART. OVER THE SW CARIBBEAN...LOW PRESSURE ASSOCIATED WITH A LOW CENTER OVER N COLOMBIA AND THE EPAC MONSOON TROUGH SUPPORT SCATTERED MODERATE CONVECTION S OF 12N BETWEEN 74W AND 84W. SAHARAN DRY AIR AND DUST ENGULFING THE NEXT TROPICAL WAVE TO ENTER THE BASIN COVERS THE E CARIBBEAN E OF 70W...THUS INHIBITING CONVECTION. REFER TO THE TROPICAL WAVES SECTION FOR MORE DETAILS. A GENERALLY TIGHT PRESSURE GRADIENT BETWEEN A RIDGE OVER THE ATLC EXTENDING ACROSS THE NORTHERN BASIN AND LOWER PRESSURE OVER COLOMBIA SUPPORT WINDS OF 20 KT TO 25 KT ACROSS THE CENTRAL CARIBBEAN MAINLY S OF 17N BETWEEN 66W-80W. TRADES OF 15 KT DOMINATE ELSEWHERE. THE NEXT TROPICAL WAVE WILL ENTER THE E CARIBBEAN LATE TONIGHT POSSIBLY ENHANCING ISOLATED SHOWERS. ...HISPANIOLA... MOISTURE ASSOCIATED WITH THE PASSAGE OF A TROPICAL WAVE WITH AXIS CURRENTLY NEAR 77W COVERS THE ISLAND AND ADJACENT WATERS. AT THE UPPER LEVELS...A DIVERGENT ENVIRONMENT SITS OVER THE ISLAND BEING GENERATED BY A LOW OVER THE BAHAMAS AND RIDGING COVERING THE CENTRAL AND SOUTHERN CARIBBEAN. BOTH THE MOIST AIR AND UPPER DIVERGENCE SUPPORT CLOUDINESS ISLAND-WIDE WITH POSSIBLE ISOLATED SHOWERS. ATLANTIC OCEAN... TWO TROPICAL WAVES ARE OVER THE TROPICAL ATLANTIC. PLEASE SEE THE TROPICAL WAVES SECTION ABOVE FOR MORE DETAILS. AS IT IS NORMAL FOR THIS TIME OF THE YEAR...THE AZORES HIGH EXTENDS A RIDGE ACROSS GREAT PORTIONS OF THE TROPICAL ATLANTIC SUPPORTING MAINLY FAIR WEATHER. OVER THE SW N ATLC...THE BASE OF A MIDDLE LEVEL TROUGH ALONG THE EASTERN CONUS AND SEABOARD GENERATES DIFFLUENT FLOW. THIS WIND FLOW ALOFT ALONG WITH MOISTURE BEING ADVECTED FROM THE CARIBBEAN AND SE CONUS SUPPORT SCATTERED HEAVY SHOWERS AND TSTMS N OF 29N W OF 77W. FARTHER SOUTH...AN UPPER LOW ANCHORED NEAR ANDROS SUPPORT SIMILAR CONVECTION FROM 21N TO 28N W OF 71W. OTHERWISE...A WEAK COLD FRONT EXTENDS OVER THE N- CENTRAL ATLC FROM 31N45W TO 29N57W WITH NO CONVECTION. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ NR