000 AXNT20 KNHC 202322 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT MON JUL 20 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...TROPICAL WAVES... TROPICAL WAVE HAS MOVED OFF THE COAST OF AFRICA AND EXTENDS FROM 05N18W TO 16N17W MOVING W AT 15-20 KT. THE WAVE COINCIDES WITH BROAD 700 MB TROUGHING ALOFT BETWEEN 15W-20W. 850 MB VORTICITY MAXIMUM ARE LOCATED NEAR THE WAVE AXIS FROM 08N-14N. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS FROM 05N-09N BETWEEN 18W-28W. TROPICAL WAVE EXTENDS FROM 06N50W TO 17N49W MOVING W AT 20 KT. THE WAVE COINCIDES WITH BROAD 700 MB TROUGHING ALOFT BETWEEN 47W- 53W ON THE SOUTHERN PERIPHERY OF A MID-LEVEL RIDGE CENTERED NEAR 23N45W. 850 MB VORTICITY MAXIMUM IS LOCATED NEAR THE NORTHERN HALF OF THE WAVE FROM 12N-15N. ISOLATED MODERATE CONVECTION IS FROM 08N-10N BETWEEN 50W-60W. TROPICAL WAVE EXTENDS FROM 08N61W TO 18N61W MOVING W AT 15-20 KT. THE WAVE REMAINS EMBEDDED WITHIN A MAXIMUM OF TOTAL PRECIPITABLE WATER BETWEEN 59W-64W THAT STRETCHES AS FAR NORTH AS 23N THEN NORTHEASTWARD INTO THE INFLUENCE OF AN UPPER LEVEL TROUGH AXIS EXTENDING OVER THE CENTRAL ATLC. ISOLATED TO WIDELY SCATTERED MODERATE TO STRONG CONVECTION IS FROM 11N-18N BETWEEN 59W-64W. SURFACE OBSERVATIONS ACROSS THE LESSER ANTILLES RECENTLY INDICATED A WIND SHIFT WITH THE PASSAGE OF THE WAVE AXIS. TROPICAL WAVE EXTENDS FROM 06N69W TO 16N68W MOVING W AT 15-20 KT. THE WAVE NEARLY COINCIDES WITH 700 MB TROUGHING BETWEEN 66W- 72W AND IS LARGELY INFLUENCED ALOFT BY SOUTHWESTERLY WIND SHEAR OVER THE CENTRAL AND EASTERN CARIBBEAN. AS A RESULT...NO SIGNIFICANT DEEP CONVECTION IS OCCURRING WITH THE WAVE AT THIS TIME. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH AXIS EXTENDS FROM NEAR 08N18W TO 07N30W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 07N30W TO 09N48W. ...DISCUSSION... GULF OF MEXICO... NORTHEASTERLY FLOW ALOFT PREVAILS OVER MUCH OF THE GULF THIS EVENING BETWEEN AN UPPER LEVEL ANTICYCLONE CENTERED OVER EAST CENTRAL TEXAS NEAR 31N96W AND AN UPPER LEVEL LOW CENTERED OVER THE NW CARIBBEAN SEA NEAR 20N86W. WHILE A MAJORITY OF THE BASIN IS UNDER THIS RELATIVELY STABLE FLOW...AT THE SURFACE...WEAK TROUGHING AND LOW-LEVEL MOISTURE CONVERGENCE IS PRESENT ACROSS THE NE TO N CENTRAL GULF EXTENDING FROM 30N84W TO 30N90W. THE SURFACE TROUGH BOUNDARY IS PROVIDING FOCUS FOR SCATTERED SHOWERS AND TSTMS OCCURRING FROM 26N-30N BETWEEN 83W-96W. OTHERWISE...A SURFACE RIDGE AXIS EXTENDS FROM THE SW NORTH ATLC INTO THE SE GULF NEAR 24N84W TO THE NW GULF ALONG THE TEXAS COAST NEAR 28N96W. MAINLY LIGHT TO MODERATE ANTICYCLONIC FLOW IS FORECAST ACROSS THE BASIN THROUGH WEDNESDAY EVENING. AN EXCEPTION WILL BE NW OF THE YUCATAN PENINSULA WHERE WINDS WILL INCREASE TO 15-20 KT EACH NIGHT AS DIURNAL TROUGHING DEVELOPS OVER THE PENINSULA AND PUSHES OFFSHORE INTO THE SW GULF. CARIBBEAN SEA... AN UPPER LEVEL LOW IS NOTED ON WATER VAPOR IMAGERY OVER THE NW CARIBBEAN CENTERED NEAR 20N86W. CONDITIONS AT THE SURFACE REMAIN FAIRLY TRANQUIL ACROSS THE NW CARIBBEAN. OTHERWISE...THE REMAINDER OF THE CARIBBEAN BASIN IS UNDER THE INFLUENCE OF SOUTHWESTERLY FLOW ALOFT ON THE NORTHERN PERIPHERY OF AN UPPER LEVEL RIDGE AXIS EXTENDING ALONG 12N-14N. THE DIFFLUENCE ASSOCIATED WITH THE RIDGING IS GENERATING SCATTERED SHOWERS AND TSTMS ACROSS PORTIONS OF THE SW CARIBBEAN AND INLAND AREAS OF PANAMA AND COSTA RICA S OF 10N BETWEEN 74W-82W. FINALLY...A PAIR OF TROPICAL WAVES ARE MOVING ACROSS THE EASTERN CARIBBEAN. INFLUENCE OF THE WESTERN-MOST WAVE ALONG 68W-69W IS LARGELY CONFINED S OF 13N WITH ISOLATED SHOWERS OCCURRING BETWEEN 66W- 71W...WITH STRONGER CONVECTION OCCURRING ACROSS PORTIONS OF NORTHERN VENEZUELA AND NORTHERN COLOMBIA. THE EASTERN WAVE ALONG 61W DID RESULT IN A WIND SHIFT ACROSS THE LESSER ANTILLES WITH CONVECTION OCCURRING AS IS DESCRIBED ABOVE RESULTING IN AN INCREASED PROBABILITY OF PRECIPITATION DURING THE NEXT 12-24 HOURS. MAINLY GENTLE TO MODERATE TRADES WILL PREVAIL ACROSS THE BASIN THROUGH THE NEXT 24-48 HOURS...EXCEPT IN THE S CENTRAL CARIBBEAN WHERE FRESH TO STRONG TRADES WILL OCCUR DUE TO A TIGHT PRESSURE GRADIENT BETWEEN CENTRAL ATLC HIGH PRES N-NE OF THE AREA AND LOW PRESSURE LOCATED ALONG THE NW COAST OF COLOMBIA. WINDS WILL ALSO PULSE TO 20 KT IN THE GULF OF HONDURAS DURING THE OVERNIGHT HOURS DUE TO A DIURNALLY RELATED PRESSURE GRADIENT INCREASE. ...HISPANIOLA... CURRENTLY...MOSTLY CLEAR SKIES PREVAIL...HOWEVER WITH THE APPROACH OF MULTIPLE TROPICAL WAVES PROGRESSING WESTWARD TO THE SOUTH OF THE ISLAND DURING THE NEXT COUPLE OF DAYS...HIGHER PROBABILITY OF SCATTERED SHOWERS AND TSTMS IS LIKELY THROUGH LATE THURSDAY INTO FRIDAY. ATLANTIC OCEAN... NORTH-NORTHEASTERLY FLOW ALOFT PREVAILS OVER MUCH OF THE SW NORTH ATLC ON THE WESTERN PERIPHERY OF AN UPPER LEVEL TROUGH AXIS EXTENDING FROM 32N45W TO 23N66W TO THE MONA PASSAGE. WHILE OVERALL CONDITIONS REMAIN STABLE ACROSS THE SW NORTH ATLC WITHIN A SURFACE RIDGE WITH AXIS ALONG 26N-27N...LOW-LEVEL MOISTURE CONVERGENCE IS MAXIMIZED ALONG 30N BETWEEN 66W-76W GENERATING SCATTERED SHOWERS AND ISOLATED SHOWERS AND TSTMS. FARTHER EAST...WITHIN THE INFLUENCE OF THE SOUTHWESTERLY FLOW ALOFT OF THE UPPER LEVEL TROUGHING...AMPLE MIDDLE TO UPPER LEVEL DYNAMICS AND LIFT ARE GENERATING AN AREA OF SCATTERED SHOWERS AND TSTMS FROM 24N-28N BETWEEN 45W-55W. THIS AREA IS OCCURRING WITHIN A NEARLY STATIONARY RIDGE ANCHORED BY A 1023 MB HIGH CENTERED NEAR 29N45W. THE RIDGE AXIS EXTENDS FROM THE HIGH TO THE CENTRAL BAHAMAS THEN WESTWARD ALL THE WAY INTO THE SE GULF OF MEXICO. PRIMARILY MODERATE ANTICYCLONIC WINDS WILL PREVAIL THROUGH THE NEXT 48 HOURS...LOCALLY UP TO 20 KT AROUND THE SOUTHERN AND WESTERN PERIPHERY OF THE SURFACE RIDGING. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ LEWITSKY