000 AXNT20 KNHC 132357 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SAT JUL 13 2013 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 2322 UTC. ...TROPICAL WAVES... A TROPICAL WAVE IS FAR IN THE EASTERN ATLC WITH AXIS EXTENDING FROM 17N20W TO 07N20W AND MOVING W NEAR 15-20 KT. TOTAL PRECIPITABLE WATER IMAGERY SHOW THE WAVE IS EMBEDDED WITHIN A HIGH MOIST ENVIRONMENT AT THE LOWER LEVELS. SCATTERED MODERATE CONVECTION IS ASSOCIATED WITH THIS WAVE FOR THE PORTION EMBEDDED WITHIN THE MONSOON TROUGH FROM 06N-11N BETWEEN 19W-24W. A TROPICAL WAVE IS IN THE CENTRAL TROPICAL ATLC WITH AXIS EXTENDING FROM 16N39W TO 07N37W AND MOVING W NEAR 10 KT. THIS WAVE IS EMBEDDED IN A MODERATE MOIST ENVIRONMENT WITHIN THE ITCZ AND HAS NO CONVECTION ASSOCIATED WITH IT AT THIS TIME. THIS WAVE IS EXPECTED TO ENTER THE EASTERN CARIBBEAN VERY EARLY ON TUESDAY. A TROPICAL WAVE IS IN THE W CARIBBEAN ALONG THE YUCATAN PENINSULA AND BELIZE COASTLINES TO NW HONDURAS. ITS AXIS EXTENDS FROM 22N86W TO 14N88W AND IS MOVING W NEAR 10 KT. THE WAVE IS EMBEDDED IN A MODERATE TO HIGH MOIST ENVIRONMENT AND SCATTERED MODERATE CONVECTION WITH ISOLATED THUNDERSTORMS ARE OBSERVED OVER THE YUCATAN PENINSULA AND PORTIONS OF BELIZE. THIS CONVECTION EXTENDS WITHIN 150 NM OFF THE COASTLINE FROM 17N-22N. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH AXIS EXTENDS FROM 09N19W TO 09N28W. THE ITCZ AXIS CONTINUES FROM 09N29W TO 11N35W THEN RESUMES W OF THE TROPICAL WAVE FROM 07N39W TO 06N49W 06N57W. ISOLATED MODERATE CONVECTION IS WITHIN 250 NM BETWEEN 24W-31W. SCATTERED MODERATE CONVECTION IS FROM 02S-06N BETWEEN 38W-49W. ...DISCUSSION... GULF OF MEXICO... IN THE UPPER LEVELS...AN ELONGATED CYCLONIC CIRCULATION FROM INDIANA TO THE BAY OF CAMPECHE SUPPORTS A 1013 MB LOW NEAR 27N88W AND A PAIR OF SURFACE TROUGHS ACROSS THE BASIN. THE FIRST TROUGH EXTENDS SW FROM THE LOW TO 24N91W TO 23N94W. THE SECOND TROUGH EXTENDS EASTWARD FROM THE LOW ALONG 27N88W TO 27N82W. SURFACE TROUGHINESS IS OVER THE SOUTHERN GULF S OF 23N ASSOCIATED WITH THE TROPICAL WAVE MOVING ACROSS THE YUCATAN PENINSULA AND BELIZE. OVER THE NW GULF...A WEAK 1014 MB HIGH IS LOCATED NEAR 27N95W. SCATTERED SHOWERS WITH ISOLATED THUNDERSTORMS ARE N OF 26N E OF 91W AS WELL AS WITHIN 60 NM N OF THE YUCATAN PENINSULA AND OVER THE YUCATAN CHANNEL. THE REMNANTS OF FORMER TROPICAL CYCLONE CHANTAL SPREADS ALONG THE FLORIDA PENINSULA AND THE STRAITS OF FLORIDA GENERATING SCATTERED MODERATED CONVECTION AND ISOLATED THUNDERSTORMS. OTHERWISE...A WEAK PRES GRADIENT PREVAILS ACROSS THE GULF WATERS PROVIDING WINDS IN THE RANGE OF 5-15 KT. THE HIGH OVER THE NW GULF IS EXPECTED TO DISSIPATE TONIGHT WHILE THE LOW IS EXPECTED TO REMAIN OVER THE NE GULF TIL LATE SUNDAY. SURFACE RIDGING IS EXPECTED TO BUILD ACROSS MOST OF THE BASIN EARLY MONDAY. CARIBBEAN SEA... THE TROPICAL WAVE THAT WAS OVER THE WESTERN CARIBBEAN NOW IS MOVING ALONG THE YUCATAN PENINSULA AND BELIZE. SCATTERED MODERATE CONVECTION WITH ISOLATED THUNDERSTORMS EXTENDS WITHIN 150 NM OFF ITS COASTLINES FROM 17N-22N. UPPER LEVEL DIFFLUENCE FROM THE ELONGATED CYCLONIC CIRCULATION EXTENDING ACROSS THE GULF AND A RIDGE OVER THE WESTERN CARIBBEAN W OF 77W COMBINED WITH TRAILING MOISTURE FROM THE WAVE IS ENHANCING SCATTERED MODERATE CONVECTION WITH ISOLATED THUNDERSTORMS OVER HONDURAS AND NICARAGUA. THIS CONVECTION EXTENDS WITHIN 60 NM N OF THE HONDURAS COASTLINE BETWEEN 85W-87W. AN UPPER LEVEL TROUGH COVERS THE REMAINDER OF THE CARIBBEAN WHICH EXTENDS FROM A BROAD CYCLONIC CIRCULATION OVER THE ATLC CENTERED NEAR 25N60W. THIS UPPER LEVEL TROUGHINESS SUPPORTS A SURFACE TROUGH MOVING ACROSS EASTERN PUERTO RICO ALONG 20N64W TO 14N66W. THIS SURFACE TROUGH HAS BEEN GENERATING RAINSHOWERS OVER THE LEEWARD ISLANDS...VIEQUES AND NOW ACROSS PUERTO RICO MAINLAND. TRADEWINDS OF 15-20 KT SPREADS ACROSS THE THE BASIN WITH THE STRONGEST WINDS OVER THE CENTRAL CARIBBEAN. OTHERWISE...DRY AIR AT LOWER AND MIDDLE LEVELS SUPPORTS FAIR WEATHER ACROSS THE REMAINDER BASIN. THE SURFACE TROUGH IS EXPECTED TO MOVE OFF THE WESTERN COAST OF PUERTO RICO VERY LATE TONIGHT AND MOVE TO LA HISPANIOLA EARLY SUNDAY. A NEW TROPICAL WAVE IS EXPECTED TO ENTER THE EASTERN BASIN EARLY TUESDAY. HISPANIOLA... CURRENTLY...DRY AIR IS ACROSS MOST OF LA HISPANIOLA. ONLY ISOLATED SHOWERS AND THUNDERSTORMS ARE OBSERVED OVER SW DOMINICAN REPUBLIC WHICH ARE BEING ENHANCED BY UPPER LEVEL TROUGHINESS. A SURFACE TROUGH CURRENTLY MOVING ACROSS PUERTO RICO IS EXPECTED TO ENTER THE DOMINICAN REPUBLIC EARLY ON SUNDAY WHICH WILL ENHANCE RAINSHOWERS ACTIVITY. THESE SHOWERS COULD BE HEAVIER DURING THE AFTERNOON AND EVENING HOURS IN ASSOCIATION WITH DIURNAL HEATING AND LOCAL ISLAND EFFECTS. ATLANTIC OCEAN... CLOUDINESS AND SHOWERS EXTENDS FROM THE NORTHWESTERN BAHAMAS NORTHWARD ACROSS THE ATLANTIC ASSOCIATED WITH THE REMNANTS OF FORMER TROPICAL CYCLONE CHANTAL. THIS ACTIVITY IS EXPECTED TO MOVE NORTHWARD AND MERGE WITH A FRONTAL SYSTEM CURRENTLY LOCATED ALONG THE EASTERN CONUS. A SURFACE TROUGH...REFLECTION OF AN UPPER LEVEL BROAD CYCLONIC CIRCULATION CENTERED NEAR 25N60W EXTENDS FROM 30N65W TO 24N66W. ISOLATED SHOWERS AND THUNDERSTORMS ARE N OF 27N BETWEEN 61W-71W. BESIDES THE SURFACE TROUGH AND THE TROPICAL WAVES ALREADY DISCUSSED...BROAD SURFACE RIDGING COVERS THE REMAINDER OF THE BASIN WHICH ALONG WITH DRY AIR AT LOWER AND MIDDLE LEVELS IS SUPPORTING FAIR WEATHER. 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