000 AXNT20 KNHC 192355 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SUN JUL 19 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 2345 UTC. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 05N39W TO 16N37W MOVING W AT 15-20 KT. THE WAVE COINCIDES WITH A BROAD 700 MB TROUGH BETWEEN 36W- 43W. 850 MB RELATIVE VORTICITY FIELDS ALSO SHOW MAXIMUM VALUES ACROSS THE NORTHERN HALF OF THE WAVE AXIS. EXAMINING THE SAHARAN AIR LAYER TRACKING PRODUCT FROM UW-CIMSS...THE WAVE IS ENCOUNTERING SAHARAN DRY AIR AND DUST WHICH IS LIMITING ASSOCIATED CONVECTION. ISOLATED MODERATE CONVECTION IS FROM 03N- 11N BETWEEN 39W-45W. TROPICAL WAVE EXTENDS FROM 08N52W TO 20N52W MOVING W AT 15 KT. THIS WAVE ALSO COINCIDES WITH A BROAD 700 MB TROUGH BETWEEN 51W- 55W. 850 MB RELATIVE VORTICITY FIELDS SHOW A VERY SMALL CONCENTRATED MAXIMUM VALUE NEAR 10N52W. THE WAVE IS ALSO MOVING THROUGH A SAHARAN DRY AIR AND DUST WHICH IS LIMITING ASSOCIATED CONVECTION. ISOLATED MODERATE CONVECTION IS FROM 09N-14N BETWEEN 52W-57W. TROPICAL WAVE EXTENDS FROM 09N59W TO 20N59W MOVING W AT 15 KT. THE WAVE COINCIDES WITH A GLOBAL MODEL INDICATED 700 MB TROUGHING BETWEEN 59W-65W. THE WAVE REMAINS EMBEDDED WITHIN A SIGNIFICANT AREA OF DUST AND A STABLE ENVIRONMENT DUE TO SAHARAN DRY AIR AND DUST. NO SIGNIFICANT CONVECTION IS OCCURRING WITH THE WAVE AT THIS TIME. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH AXIS EXTENDS FROM THE COAST OF AFRICA NEAR 11N15W TO 08N26W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 08N26W TO 10N32W TO 05N52W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS FROM 06N-11N BETWEEN 20W-27W LIKELY AHEAD OF THE NEXT TROPICAL WAVE WHICH IS MOVING OFF OF THE COAST OF AFRICA. ISOLATED MODERATE CONVECTION IS S OF 06N BETWEEN 47W-51W. ...DISCUSSION... GULF OF MEXICO... A BROAD MIDDLE TO UPPER LEVEL ANTICYCLONE CENTERED OVER NORTHEASTERN LOUISIANA COVERS THE BASIN EXCEPT THE SW GULF WHERE AN INVERTED TROUGH IS OBSERVED. AT THE SURFACE...A WEAK TROUGH EXTENDS FROM THE NORTHEAST GULF NEAR APALACHEE BAY FLORIDA SW-W TO 27N92W. THIS TROUGH IS BECOMING LESS DEFINED WHILE A MORE WELL DEFINED TROUGH IS SINKING SOUTHWARD FROM SOUTHERN GEORGIA NEAR 32N82W SW-W TO 30N90W. ISOLATED TSTMS ARE OCCURRING N OF 26N E OF 92W WITH MORE CONCENTRATED ACTIVITY INLAND NEAR THE OTHER TROUGH. OTHERWISE...A SURFACE RIDGE DOMINATES THE GULF ANCHORED BY 1019 MB HIGH PRESSURE NEAR 25N88W WITH THE AXIS EXTENDING NW TO THE TEXAS COAST AND E-SE TO THE STRAITS OF FLORIDA. MAINLY LIGHT TO OCCASIONAL MODERATE ANTICYCLONIC WINDS WILL PREVAIL ACROSS THE BASIN THROUGH THE NEXT 48 HOURS... EXCEPT NEAR THE NW COAST OF THE YUCATAN PENINSULA WHERE DIURNAL TROUGHING WILL FORM INLAND AND WILL PUSH TO THE W OFFSHORE WITH WINDS INCREASING TO 15-20 KT AHEAD OF THE FEATURE EACH NIGHT. CARIBBEAN SEA... AN UPPER LEVEL CYCLONE IS OVER THE NW CARIBBEAN NEAR 17N86W. THIS FEATURE IS SUPPORTING A SURFACE TROUGH WHICH EXTENDS FROM THE ISLE OF YOUTH CUBA S TO EASTERN HONDURAS. ISOLATED TSTMS ARE OCCURRING NEAR THE TROUGH AXIS. ELSEWHERE ACROSS THE BASIN...SOUTHWESTERLY FLOW ALOFT PREVAILS WITH AN UPPER LEVEL RIDGE EXTENDING FROM EAST TO WEST ALONG 12N-14N. UPPER LEVEL DIFFLUENCE IS OVER THE SW CARIBBEAN WITH ISOLATED TO WIDELY SCATTERED TSTMS THERE. MAINLY GENTLE TO MODERATE TRADES WILL PREVAIL ACROSS THE BASIN THROUGH THE NEXT 48 HOURS...EXCEPT IN THE S CENTRAL CARIBBEAN WHERE A TIGHT PRESSURE GRADIENT BETWEEN ATLC HIGH PRESSURE N-NE OF THE AREA AND LOW PRESSURE NEAR AND ALONG THE COAST OF COLOMBIA. THESE GRADIENT WILL SUPPORT FRESH TO STRONG WINDS...STRONGEST JUST NW OF THE COAST OF COLOMBIA. ...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 TUESDAY WITH THE STABLE CONDITIONS EXPECTED TO PERSIST. ATLANTIC OCEAN... UPPER LEVEL NORTHERLY FLOW INFLUENCES MUCH OF THE SW NORTH ATLC W OF 68W 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 SURFACE TROUGH ANALYZED FROM 31N74W TO 30N79W... GENERATING SCATTERED SHOWERS AND TSTMS N OF 28N BETWEEN 70W-79W. TO THE EAST OF THE TROUGH...AN UPPER LEVEL LOW IS CENTERED NEAR 30N50W AND IS GENERATING AN AREA OF ISOLATED SHOWERS AND TSTMS FROM 27N-30N BETWEEN 56W-65W. A SURFACE RIDGE EXTENDS FROM EAST TO WEST ALONG 27N-28N ANCHORED BY 1021 MB HIGH PRESSURE NEAR 29N69W. 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 29N44W. MAINLY MODERATE ANTICYCLONIC WINDS WILL PREVAIL THROUGH TUESDAY EXCEPT ALONG AND AROUND THE SOUTHERN AND WESTERN PERIPHERY OF THE RIDGING WHERE WINDS WILL LOCALLY INCREASE TO FRESH LEVELS WITH A TIGHTENING PRESSURE GRADIENT. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ LEWITSKY