000 AXNT20 KNHC 182355 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT FRI JUL 18 2014 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 IS OVER THE CAPE VERDE ISLANDS WITH AXIS EXTENDING FROM 17N24W TO 7N24W MOVING W 10 TO 15 KT OVER THE PAST 24 HOURS. THE SOUTHERN PORTION OF THE WAVE IS EMBEDDED IN THE MONSOON TROUGH WHICH IS SUPPORTING SCATTERED MODERATE TO STRONG CONVECTION FROM 6N-9N BETWEEN 26W-30W. ELSEWHERE...DRY SAHARAN AIR INTERACTING WITH THE WAVE HAS SUPPRESSED CONVECTIVE DEVELOPMENT. TROPICAL WAVE IS OVER THE CENTRAL ATLC WITH AXIS EXTENDING FROM 14N44W TO 7N46W MOVING W AT 15 KT OVER THE PAST 24 HOURS. THE LOW-AMPLITUDE WAVE IS EMBEDDED IN THE MOIST ENVIRONMENT OF THE ITCZ/MONSOON TROUGH. CURRENTLY ONLY ISOLATED MODERATE CONVECTION WAS NOTED FROM 8N-11N BETWEEN 42W-50W. TROPICAL WAVE IS MOVING ACROSS THE WINDWARD ISLANDS. ITS AXIS EXTENDS FROM 16N60W TO 7N63W AND IS MOVING W AT 15-20 KT OVER THE PAST 24 HOURS. A DEEP LAYER MOIST ENVIRONMENT IS ASSOCIATED WITH THE WAVE. A 1312 UTC ASCAT PASS CAPTURED THE WAVE AXIS E OF THE WINDWARD ISLANDS EARLIER TODAY. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE TROPICAL ATLC ON THE COAST OF SENEGAL NEAR 13N17W AND CONTINUES ALONG 9N25W TO 9N39W. THE ITCZ BEGINS NEAR 9N39W AND CONTINUES TO 7N55W TO NEAR TRINIDAD AT 10N61W. IN ADDITION TO THE CONVECTION ASSOCIATED WITH THE WAVES...SCATTERED MODERATE CONVECTION IS FROM 6N-10N BETWEEN 30W-37W. ...DISCUSSION... GULF OF MEXICO... A VERY SHARP MID-TO UPPER LEVEL TROUGH FOR JULY EXTENDS FROM THE GREAT LAKES SW TO A BASE OVER EAST TEXAS/LOUISIANA AND SUPPORTS A STATIONARY FRONT ALONG THE GULF COAST FROM THE FLORIDA PANHANDLE TO TEXAS. A PRE-FRONTAL TROUGH EXTENDED FROM NEAR NEW ORLEANS TO LAFAYETTE LOUISIANA...BRIEFLY INTO THE GULF OF MEXICO AND TO THE TEXAS COAST JUST S OF GALVESTON THEN CONTINUES INTO NE MEXICO TO A 1010 MB LOW OVER THE HIGH TERRAIN. AN UPPER LEVEL ANTICYCLONE DOMINATED THE PATTERN OVER THE GULF AND WAS ORIENTED E TO W ALONG 27N/28N. SATELLITE DERIVED WINDS INDICATED STRONG EASTERLIES OF 40-50 KT ON THE SOUTHSIDE OF THE ANTICYCLONE OVER THE SOUTHERN GULF AND BAY OF CAMPECHE. A LINE OF STRONG THUNDERSTORMS AND SQUALL LINE EXTENDED FROM PENSACOLA FLORIDA TO 110 NM SSE OF NEW ORLEANS. ADDITIONAL STRONG ACTIVITY WAS NOTED ABOUT 75 NM S OF LAFAYETTE LOUISIANA. SCATTERED SHOWERS ISOLATED THUNDERSTORMS WERE NOTED ELSEWHERE N OF 27N W OF 90W AND WERE ENHANCED BY DIFFLUENCE ALOFT. OTHERWISE...SURFACE WINDS ARE GENERALLY LIGHT AND VARIABLE OVER THE GULF BECOMING MORE SOUTHERLY AT 10-15 KT W OF 90W. SURFACE RIDGING AND RETURN FLOW WILL DOMINATE ACROSS THE REGION FOR THE NEXT TWO DAYS. CARIBBEAN SEA... AN UPPER LEVEL TROUGH/SHEAR AXIS BISECTS THE CARIBBEAN AND EXTENDS FROM THE MONA PASSAGE THROUGH 15N75W TO A FAIRLY EXTENSIVE CYCLONIC CIRCULATION OVER HONDURAS. A TROPICAL WAVE IS MOVING ACROSS THE WINDWARD ISLANDS INTO THE EXTREME E CARIBBEAN SEA. CONVECTIVE ACTIVITY WITH THE WAVE HAS DECREASED SIGNIFICANTLY OVER THE PAST SEVERAL HOURS WITH ONLY WIDELY SCATTERED SHOWERS NEAR GRENADA AND THE ENTRANCE TO THE CARIBBEAN SEA. THE WAVE WAS EMBEDDED WITHIN AN AREA OF ANTICYCLONIC SOUTHWESTERLY FLOW ALOFT TO THE SE OF THE UPPER TROUGH. HIGHER SURFACE PRESSURES ACROSS THE NORTHERN CARIBBEAN AND LOWER PRESSURES OVER COLOMBIA CONTINUE TO SUPPORT A TIGHT PRESSURE GRADIENT OVER THE SOUTHERN-CENTRAL PORTION OF THE BASIN. A 1406 UTC ASCAT PASS CAPTURED AN AREA OF 25 TO LOCALLY 30 KT WINDS OVER THE CARIBBEAN FROM 11N TO 15N BETWEEN 72W AND 77W. THE WAVE IS FORECAST TO PASS S OF HISPANIOLA SAT NIGHT AND EARLY SUN. THE NEXT TROPICAL WAVE IS EXPECTED TO ENTER THE EASTERN PORTION OF THE BASIN BY MON. ...HISPANIOLA... THE PROXIMITY OF THE UPPER LEVEL TROUGH/SHEAR AXIS TO HISPANIOLA HAS RESULTED IN ENOUGH DESTABILIZATION TO PRODUCE MORE WIDESPREAD CONVECTION OVER THE INTERIOR OF THE ISLAND THIS AFTERNOON AND EVENING THAN IN PREVIOUS DAYS. A TROPICAL WAVE OVER THE WINDWARD ISLANDS IS EXPECTED TO MOVE S OF THE ISLAND SAT NIGHT AND SUN AND WITH THE PRESENCE OF THE UPPER LEVEL TROUGH ANOTHER ROUND OF WIDESPREAD SHOWERS/THUNDERSTORMS ARE EXPECTED OVER THE ISLAND SAT AFTERNOON AND THROUGH THE WEEKEND. ATLANTIC OCEAN... A MID-LEVEL SHORT-WAVE INVERTED TROUGH IS OVER THE SW N ATLC WITH UPPER-LEVEL DIVERGENCE TO THE S OF THE TROUGH OVER THE BAHAMAS. THIS ENVIRONMENT ALONG WITH ABUNDANT MOISTURE IN THE REGION CONTINUE TO SUPPORT SCATTERED SHOWERS AND ISOLATED TSTMS N OF 22N BETWEEN 70W-76W. FARTHER EAST...A MID-UPPER LEVEL LOW CENTERED NEAR 27N52W WAS RACING WESTWARD AT 20-25 KT. THIS LOW WAS SUPPORTING SCATTERED SHOWERS WITHIN 180 NM W OF A SURFACE TROUGH EXTENDING FROM 32N48W TO 26N51W. FURTHER EAST...A DYING COLD FRONT ENTERED THE AREA NEAR 32N25W AND EXTENDED TO 28N35W. OTHERWISE...THE CENTRAL AND EASTERN ATLC ARE UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1031 MB HIGH CENTERED NEAR 37N50W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ COBB