000 AXNT20 KNHC 182350 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT THU JUL 18 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 2245 UTC. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 22N33W TO 10N35W MOVING WEST AT 15-20 KT. THE WAVE LIES WITHIN A LARGE SURGE OF MOISTURE EVIDENT IN TOTAL PRECIPITABLE WATER IMAGERY. A 700 MB TROUGH AXIS ALSO ALIGNS WELL WITH THE WAVE AXIS. DUE TO THE PRESENCE OF A SAHARAN AIR LAYER SURROUNDING THE WAVE...NO DEEP CONVECTION IS CURRENTLY ASSOCIATED WITH THE AXIS. TROPICAL WAVE EXTENDS FROM 21N65W TO 14N70W MOVING W AT 15-20 KT. THE WAVE IS EMBEDDED WITHIN AN AREA OF INCREASED MOISTURE PRESENT IN TOTAL PRECIPITABLE WATER IMAGERY. BROAD LOW-LEVEL CYCLONIC FLOW IS ALSO EVIDENT AROUND THE WAVE AXIS. SCATTERED MODERATE/STRONG CONVECTION IS NEAR THE NORTHERN HALF OF THE WAVE FROM 17N-23N BETWEEN 64W-68W...AND FROM 18N-21N BETWEEN 68W-75W. THIS ACTIVITY IS BRINGING HEAVY RAINFALL TO BOTH PUERTO RICO AND HISPANIOLA. TROPICAL WAVE EXTENDS FROM 13N79W TO 6N80W MOVING W AT 10-15 KT. MAXIMUM MOISTURE IS EVIDENT NEAR THE WAVE AXIS IN THE E PACIFIC. THE WAVE IS ALSO MOVING THROUGH THE MONSOON TROUGH. THE COMBINATION OF THE WAVE AND MONSOON TROUGH IS PRODUCING NUMEROUS STRONG CONVECTION FROM 8N-11N BETWEEN 77W-83W COVERING MUCH OF PANAMA. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE COAST OF GUINEA-BISSAU NEAR 11N16W TO 10N24W. THE ITCZ BEGINS NEAR 10N24W AND CONTINUES ALONG 12N29W 8N43W 4N53W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 6N-9N BETWEEN 38W-55W. ...DISCUSSION... GULF OF MEXICO... AN UPPER LEVEL LOW CONTINUES TO IMPACT THE GULF OF MEXICO CENTERED OVER THE NORTH CENTRAL GULF NEAR 28N90W. A BROAD AREA OF DIFFLUENCE ALOFT SPREADS FROM THE YUCATAN PENINSULA ACROSS THE EASTERN GULF INCLUDING MUCH OF FLORIDA. THIS IS WHERE MOIST CONDITIONS ARE PRESENT ALONG WITH BROAD LOW-LEVEL TROUGHING. A SURFACE TROUGH AXIS EXTENDS ALONG 28N81W TO 27N86W 24N90W. HEAVY SHOWERS/THUNDERSTORMS COVER THE YUCATAN PENINSULA. SCATTERED SHOWERS/THUNDERSTORMS ARE ALSO OVER THE EASTERN GULF AND FLORIDA FROM 24N-29N BETWEEN 79W-87W. SOME AREAS OF SE FLORIDA HAVE SEEN FLOODING THROUGHOUT THE DAY. A SECOND SURFACE TROUGH IS NEAR THE COAST OF MEXICO ALONG 27N97W TO 20N94W. ONLY A FEW ISOLATED SHOWERS ARE NEAR THE AXIS. THE BROAD SURFACE TROUGH OVER THE EASTERN GULF WILL CONTINUE TO DRIFT WEST OVER THE NEXT DAY OR SO. THE UPPER LEVEL LOW WILL ALSO CONTINUE TO PROVIDE DIFFLUENT FLOW OF THE EASTERN AND CENTRAL GULF...WHICH WILL LIKELY LEAD TO MORE SHOWER/THUNDERSTORM ACTIVITY. MOISTURE ASSOCIATED WITH A TROPICAL WAVE CURRENTLY OVER THE EASTERN CARIBBEAN WILL ALSO BRING INCREASED ACTIVITY TO THE SE GULF OVER THE WEEKEND. CARIBBEAN SEA... UPPER LEVEL TROUGHING ASSOCIATED WITH AN UPPER LEVEL LOW OVER THE GULF OF MEXICO CONTINUES EXTENDS DOWN THE YUCATAN PENINSULA PROVIDING DIFFLUENT FLOW ALOFT OVER THE NW CARIBBEAN PRODUCING A FEW SHOWERS/THUNDERSTORMS IN THE NW WATERS AS WELL AS WESTERN CUBA. WEAK UPPER RIDGING COVERS THE REMAINDER OF THE WESTERN CARIBBEAN. A TROPICAL WAVE IN THE SW CARIBBEAN IS SUPPORTING HEAVY SHOWERS/THUNDERSTORMS ACROSS PANAMA. THE MONSOON TROUGH ALONG 9N IS ALSO ENHANCING ACTIVITY. SCATTERED SHOWERS/THUNDERSTORMS ARE ALSO OVER MUCH OF NICARAGUA AND HONDURAS. A BROAD UPPER LEVEL LOW IS OVER THE EASTERN CARIBBEAN NEAR 13N69W ENHANCING ACTIVITY NEAR A TROPICAL WAVE EXTENDING THROUGH THE MONA PASSAGE. STRONG SHOWERS/THUNDERSTORMS ARE OVER BOTH HISPANIOLA AND PUERTO RICO. THE REMAINDER OF THE BASIN IS RELATIVELY FAIR. TRADEWIND FLOW OF 15-20 KT IS THROUGHOUT REACHING 25 KT NEAR THE COAST OF COLOMBIA. THE TROPICAL WAVE IN THE SW CARIBBEAN IS EXPECTED TO CONTINUE WEST AND MOVE INTO THE E PACIFIC. THE WAVE IN THE EASTERN CARIBBEAN WILL ALSO CONTINUE WEST BRINGING MOIST CONDITIONS TO THE CENTRAL CARIBBEAN TOMORROW...AND TO THE WESTERN CARIBBEAN AND SE GULF ON SATURDAY. HISPANIOLA... VERY STRONG SHOWERS/THUNDERSTORMS ARE CURRENTLY ACROSS HISPANIOLA FROM 18N-20N BETWEEN 69W-75W ASSOCIATED WITH A TROPICAL WAVE STILL EAST OF THE ISLAND. FLOODING IS POSSIBLE IN AREAS OF HIGH TERRAIN AND THE THREAT WILL CONTINUE AS THE WAVE PASSES. MOISTURE NEAR THE WAVE WILL REMAIN IMPACTING THE ISLAND THROUGH MIDDAY TOMORROW BEFORE DRIER AIR MOVES IN. ATLANTIC OCEAN... MOISTURE ASSOCIATED WITH AN UPPER LEVEL LOW/SURFACE TROUGH IN THE GULF OF MEXICO CONTINUES AROUND AN UPPER LEVEL RIDGE ALONG 80W. SCATTERED SHOWERS/THUNDERSTORMS ARE FROM 24N-28N WEST OF 78W. A SMALL PORTION OF THE SURFACE TROUGH ALSO EXTENDS INTO THE WEST ATLC ALONG 28N80W TO 30N79W. BROAD SURFACE RIDGING DOMINATES THE REMAINDER OF THE WEST AND CENTRAL ATLC AROUND A 1024 MB HIGH NEAR 29N58W. BROAD UPPER TROUGHING COVERS A GOOD PORTION OF THE AREA AND IS HELPING ENHANCE ACTIVITY NEAR A TROPICAL WAVE THAT EXTENDS THROUGH THE MONA PASSAGE TO NEAR 21N65W. SCATTERED SHOWERS/THUNDERSTORMS ARE FROM 19N-22N BETWEEN 64W-70W. THE REMAINDER OF THE BASIN IS COVERED BY A BROAD UPPER RIDGE CENTERED NEAR 20N33W. THE UPPER RIDGE SUPPORTS A SECOND SURFACE HIGH CENTER...A 1024 MB HIGH NEAR 27N45W. A DRY SAHARAN AIR LAYER COVERS MUCH OF THE TROPICAL ATLC EXTENDING FROM THE COAST OF AFRICA AROUND THE TROPICAL WAVE IN THE EASTERN ATLC TO NEAR 55W KEEPING CONDITIONS FAIR ACROSS THIS AREA. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON