000 AXNT20 KNHC 182347 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SAT JUL 18 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 EXTENDS FROM 07N32W TO 18N29W MOVING W AT 15-20 KT. THE WAVE COINCIDES WITH A BROAD 700 MB TROUGH BETWEEN 25W- 35W. 850 MB RELATIVE VORTICITY FIELDS ALSO SHOW MAXIMUM VALUES ACROSS THE NORTHERN HALF OF THE WAVE AXIS. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS FROM 03N-10N BETWEEN 29W-37W. TROPICAL WAVE EXTENDS FROM 09N44W TO 18N45W MOVING W AT 20 KT. THIS WAVE ALSO COINCIDES WITH A BROAD 700 MB TROUGH BETWEEN 43W- 48W. 850 MB RELATIVE VORTICITY FIELDS SHOW MAXIMUM VALUES ACROSS THE FAR SOUTHERN PART OF THE WAVE AXIS. SCATTERED MODERATE CONVECTION IS FROM 11N-13N BETWEEN 45W-47W. TROPICAL WAVE EXTENDS FROM 19N59W TO 20N54W MOVING W AT 20 KT. THE WAVE COINCIDES WITH A GLOBAL MODEL INDICATED 700 MB TROUGHING BETWEEN 51W-61W. EXAMINING THE SAHARAN AIR LAYER TRACKING PRODUCT FROM UW-CIMSS...THE WAVE REMAINS EMBEDDED WITHIN A SIGNIFICANT AREA OF DUST AND A STABLE ENVIRONMENT AS A RESULT. NO SIGNIFICANT CONVECTION IS OCCURRING WITH THE WAVE AT THIS TIME. TROPICAL WAVE EXTENDS FROM THE TROPICAL NE PACIFIC OCEAN NEAR 10N87W TO THE WESTERN GULF OF HONDURAS NEAR 18N88W MOVING W AT 15-20 KT. THE WAVE COINCIDES WITH BROAD GLOBAL MODEL INDICATED 700 MB TROUGHING ACROSS THE FAR NORTHWESTERN CARIBBEAN SEA AND CENTRAL AMERICA. NO CONVECTION ASSOCIATED WITH THE WAVE IS EVIDENT ACROSS THE GULF OF HONDURAS ALTHOUGH THE WAVE MAY BE HELPING TO ENHANCE DIURNAL TSTM DEVELOPMENT OVER NEARBY LAND. ...ITCZ/MONSOON TROUGH... THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 06N33W TO 05N40W TO 05N50W. ASIDE FROM CONVECTION ASSOCIATED WITH THE EASTERN TROPICAL WAVE...WIDELY SCATTERED MODERATE CONVECTION IS FROM 02N-05N BETWEEN 37W-44W. ...DISCUSSION... GULF OF MEXICO... UPPER LEVEL NORTHEASTERLY FLOW IS OCCURRING OVER MUCH OF THE GULF ON THE SOUTHEASTERN PERIPHERY OF A MIDDLE TO UPPER LEVEL RIDGE ANCHORED OVER EAST TEXAS NEAR 29N95W. A MID-LEVEL WEAKNESS NOTED ON WATER VAPOR IMAGERY OVER THE NE GULF NEAR 29N86W SUPPORTS A SMALL AREA OF LOWER PRESSURE FOCUSED IN THE VICINITY OF A 1016 MB LOW CENTERED JUST SW OF APALACHEE BAY FLORIDA NEAR 29N85W. A SURFACE TROUGH IS ANALYZED FROM 30N84W TO THE LOW CONTINUING TO THE W-SW TO NEAR THE SE TIP OF LOUISIANA. LOW- LEVEL MOISTURE CONVERGENCE ALONG AND TO THE SOUTH OF THE BOUNDARY ALONG WITH FAVORABLE MIDDLE TO UPPER LEVEL DIFFLUENCE IS GENERATING ISOLATED TO WIDELY SCATTERED SHOWERS AND TSTMS FROM 25N-30N E OF 90W. OTHERWISE...THE REMAINDER OF THE BASIN IS UNDER THE INFLUENCE OF SURFACE RIDGING ANCHORED BY A 1020 MB HIGH CENTERED NEAR 27N91W. A RIDGE AXIS EXTENDS NW FROM THE HIGH TO THE TEXAS COAST NEAR 29N94W AND ALSO TO THE E-SE NEAR THE SW FLORIDA COAST. GENERALLY GENTLE TO MODERATE ANTICYCLONIC WINDS PREVAIL WITH LITTLE CHANGE ANTICIPATED THROUGH THE NEXT 48 HOURS. THE EXCEPTION WILL BE NEAR THE NW COAST OF THE YUCATAN PENINSULA WHERE DIURNAL TROUGHING WILL ALLOW FOR WINDS TO PULSE TO 20 KT EACH NIGHT. THE SURFACE RIDGE IS FORECAST TO REMAIN NEARLY STATIONARY AND ANCHORED ACROSS THE CENTRAL GULF WATERS THROUGH MONDAY AFTERNOON. CARIBBEAN SEA... GENERALLY NORTHEASTERLY FLOW ALOFT IS NOTED ON WATER VAPOR WITHIN THE WESTERN PERIPHERY OF UPPER LEVEL TROUGHING STEMMING FROM AN UPPER LEVEL LOW CENTERED N OF PUERTO RICO. THE TROUGH AXIS EXTENDS FROM THE UPPER LEVEL LOW SW TO OVER HISPANIOLA NEAR 20N70W TO A BROAD BASE OVER THE SW CARIBBEAN. MOST OF THE WESTERN CARIBBEAN REMAINS RELATIVELY STABLE...HOWEVER MID-LEVEL ENERGY IS FOUND SOUTH OF CUBA GENERATING ISOLATED TSTMS N OF 17N BETWEEN 76W-86W. OTHERWISE...LIMITED CONVECTION IS ACROSS THE BASIN EXCEPT NEAR THE COAST OF COLOMBIA WHERE NUMEROUS TSTMS ARE PRESENT AND ACROSS CENTRAL AMERICA WHERE A TROPICAL WAVE IS MOVING THROUGH INTO THE NE PACIFIC OCEAN. TO THE EAST OF THE UPPER LEVEL TROUGH AXIS...SOUTHWESTERLY FLOW ALOFT PREVAILS WITH ONLY SCATTERED MIDDLE TO UPPER LEVEL CLOUDINESS NOTED ON SATELLITE IMAGERY. FINALLY...FRESH TO STRONG TRADES CONTINUE ACROSS CENTRAL PORTIONS DUE TO A STRENGTHENED PRESSURE GRADIENT BETWEEN HIGH PRESSURE TO THE N OF THE AREA OVER THE SW N ATLC AND LOW PRESSURE ALONG THE COAST OF COLOMBIA NEAR 10N76W. THESE WINDS ARE EXPECTED TO PERSIST THROUGH THE WEEKEND AND INTO EARLY MONDAY GENERALLY BETWEEN 70W-80W...GRADUALLY DIMINISHING TO 20 KT OR LESS MONDAY AFTERNOON. ...HISPANIOLA... CURRENTLY...ONLY A FEW ISOLATED SHOWERS AND TSTMS HAVE MANAGED TO DEVELOP DURING THE AFTERNOON HEATING HOURS WITH DRY CONDITIONS PRESENT ALOFT MAINLY DUE TO SAHARAN DUST AND THE SAHARAN AIR LAYER PROVIDING FOR A STABLE ENVIRONMENT FOR HISPANIOLA. THE PROBABILITY FOR CONVECTION WILL REMAIN LOW THROUGH MONDAY WITH THE STABLE CONDITIONS EXPECTED TO PERSIST. ATLANTIC OCEAN... UPPER LEVEL NORTHERLY FLOW INFLUENCES MUCH OF THE SW NORTH ATLC W OF 70W ON THE EASTERN PERIPHERY OF UPPER LEVEL RIDGING ANCHORED OVER THE LOWER MISSISSIPPI RIVER VALLEY THIS EVENING. THIS IS PROVIDING FOR A RELATIVELY DIFFLUENT ENVIRONMENT ALOFT AND COUPLED WITH LOW-LEVEL MOISTURE CONVERGENCE FOCUSED ALONG AND SOUTH OF A WEAKENING SURFACE TROUGH ANALYZED FROM 32N73W TO JACKSONVILLE FLORIDA NEAR 31N81W...GENERATING SCATTERED SHOWERS AND TSTMS N OF 27N BETWEEN 67W-77W. TO THE SOUTHEAST OF THE TROUGH...AN UPPER LEVEL LOW IS CENTERED NEAR 26N58W AND IS GENERATING AN AREA OF ISOLATED SHOWERS AND TSTMS FROM 24N-29N BETWEEN 60W-67W ON THE SOUTHERN PERIPHERY OF A SURFACE RIDGE ANCHORED BY A 1021 MB HIGH CENTERED NEAR 28N66W. FARTHER TO THE EAST...THE REMAINDER OF THE ATLC IS UNDER THE INFLUENCE OF ANOTHER SURFACE RIDGE ANCHORED BY A 1024 MB HIGH CENTERED NEAR 29N40W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ LEWITSKY