000 AXNT20 KNHC 161735 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT TUE JUL 16 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 1715 UTC. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 20N50W TO 10N49W MOVING W NEAR 20 KT. THE WAVE IS EMBEDDED WITHIN A LARGE SURGE OF DEEP LAYER MOISTURE AS DEPICTED ON THE TOTAL PRECIPITABLE WATER IMAGERY. HOWEVER...A SAHARAN AIR LAYER WRAPS AROUND THE WAVE LIMITING ANY DEEP CONVECTION. TROPICAL WAVE EXTENDS FROM 18N62W OVER THE LEEWARD ISLANDS TO 10N58W W 15-20 KT. THE WAVE IS EMBEDDED WITHIN A NARROW SURGE OF DEEP LAYER MOISTURE AS DEPICTED ON THE TOTAL PRECIPITABLE WATER IMAGERY. THE LEADING EDGE OF THE SAHARAN AIR LAYER TRAILS THIS WAVE. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE FROM 14N-18N BETWEEN 61W-64W. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS AFRICA THROUGH A WEAK 1010 MB LOW INLAND OVER MAURITANIA INTO THE TROPICAL ATLC NEAR 20N16W THEN CONTINUES ALONG 14N20W TO 6N31W WHERE THE ITCZ BEGINS AND CONTINUES ALONG 4N41W TO SOUTH AMERICA NEAR 5N53W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 5N-12N E OF 21W TO THE COAST OF W AFRICA. ...DISCUSSION... GULF OF MEXICO... A CUTOFF UPPER LOW IS IN THE SW GULF NEAR 22N92W SUPPORTING A SURFACE TROUGH THAT EXTENDS 26N96W TO THE BAY OF CAMPECHE NEAR 19N94W. SCATTERED SHOWERS/THUNDERSTORMS ARE WITHIN 90 NM EITHER SIDE OF THE SURFACE TROUGH WITH SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 22N-26N BETWEEN 91W-95W. AN UPPER RIDGE COVERS THE NW GULF ANCHORED NEAR THE MISSISSIPPI DELTA PROVIDING DIFFLUENCE ALOFT TO GENERATE SCATTERED SHOWERS/ISOLATED THUNDERSTORMS N OF 27N BETWEEN 85W-96W. AN UPPER TROUGH OVER THE W ATLC IS ACROSS FLORIDA INTO THE E GULF WITH THE ASSOCIATED SURFACE TROUGH ALONG THE E COAST OF FLORIDA GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS OVER THE STRAITS OF FLORIDA AND S FLORIDA S OF LAKE OKEECHOBEE E OF 83W. A SURFACE RIDGE COVERS THE N GULF ANCHORED BY A 1025 MB HIGH OFF THE NORTH CAROLINA COAST. SURFACE RIDGE WILL MAINTAIN MODERATE E TO SE WINDS ACROSS MOST OF GULF THROUGH SAT. CARIBBEAN SEA... AN UPPER LEVEL RIDGE COVERS THE NW CARIBBEAN W OF 80W ANCHORED OVER CENTRAL AMERICA PROVIDING DIFFLUENCE ALOFT TO GENERATE SCATTERED SHOWERS/ISOLATED THUNDERSTORMS N OF 19N BETWEEN 78W- 85W. A BROAD LOW AMPLITUDE UPPER TROUGH EXTENDS FROM THE W ATLC OVER THE CENTRAL CARIBBEAN WHILE A SECOND UPPER RIDGE COVERS THE FAR E CARIBBEAN ANCHORED ALONG THE COAST OF VENEZUELA. A TROPICAL WAVE IS BENEATH THIS UPPER RIDGE OVER THE LEEWARD ISLANDS. THE MONSOON TROUGH EXTENDS FROM COLOMBIA NEAR 9N75W OVER PANAMA NEAR 9N79W TO ACROSS COSTA RICA NEAR 10N83W GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 60/75 NM EITHER SIDE OF THE MONSOON TROUGH W OF 80W. THIS IS LEAVING THE REMAINDER OF THE CARIBBEAN UNDER MOSTLY CLEAR SKIES THIS AFTERNOON. TROPICAL WAVE OVER THE LEEWARD ISLANDS WILL MOVE THROUGH THE E CARIBBEAN TODAY AND INTO THE CENTRAL CARIBBEAN THU. ANOTHER TROPICAL WAVE WILL REACH THE E CARIBBEAN FRI. HISPANIOLA... CURRENTLY ISOLATED SHOWERS ARE POSSIBLE OVER HISPANIOLA AND AFTERNOON THUNDERSTORMS COULD STILL DEVELOP WITH DAYTIME HEATING. THE UPPER TROUGH HAS DAMPENED OUT...THUS STRONG THUNDERSTORMS HAVE NOT BEEN GENERATED. THE NEXT TROPICAL WAVE IS CURRENTLY OVER THE LEEWARD ISLANDS AND WILL PASS S OF HISPANIOLA THU AND FRI INCREASING THE CHANCE OF HEAVY PRECIPITATION. ATLANTIC OCEAN... A BROAD UPPER TROUGH COVERS THE W ATLC W OF 65W TO ACROSS FLORIDA INTO THE FAR E GULF OF MEXICO WITH THE DOMINATE UPPER LOW OVER S FLORIDA NEAR 26N81W. THIS UPPER LOW IS SUPPORTING A SURFACE TROUGH THAT EXTENDS ALONG THE FLORIDA COAST FROM JUST OFF VERO BEACH TO RIGHT ON THE COAST NEAR MIAMI ACROSS THE STRAITS OF FLORIDA TO THE N COAST OF CUBA NEAR 22N79W. SCATTERED SHOWERS/THUNDERSTORMS ARE N OF 21N AND S OF LINE FROM 24N69W TO OVER FLORIDA NEAR 28N80W. A SECOND SURFACE TROUGH EXTENDS FROM 30N69W TO 23N64W WITH SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 225/250 NM E OF THE TROUGH. THE REMAINDER OF THE ATLC IS DOMINATED BY A BROAD SURFACE RIDGE ANCHORED BY A 1025 MB HIGH NEAR 28N38W. SURFACE TROUGH ALONG THE FLORIDA COAST WILL MOVE INLAND TODAY. SURFACE RIDGE WILL EXTENDS WEST TODAY THEN DRIFT S TO 32N WED AND 30N THU THROUGH SAT. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ PAW