000 AXNT20 KNHC 192343 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT FRI JUL 19 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 21N40W TO 10N43W 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 MAINLY TO THE EAST AND NORTH...NO DEEP CONVECTION IS CURRENTLY ASSOCIATED WITH THE AXIS. TROPICAL WAVE EXTENDS FROM 18N76W TO 11N77W MOVING W AT 15-20 KT. THE WAVE IS EMBEDDED WITHIN AN AREA OF INCREASED MOISTURE PRESENT IN TOTAL PRECIPITABLE WATER IMAGERY. MOST OF THE ENERGY ASSOCIATED WITH THE WAVE HAS BEEN PULLED NORTH NEAR A SURFACE TROUGH OVER THE BAHAMAS. A LARGE CLUSTER OF STRONG CONVECTION IS OVER NORTHERN COLOMBIA NEAR THE SOUTHERN TIP OF THE AXIS FROM 9N- 11N BETWEEN 73W-76W. SCATTERED MODERATE/STRONG CONVECTION IS ALSO NEAR THE NORTHERN TIP OF THE WAVE FROM 18N-19N BETWEEN 75W- 80W. MORE ACTIVITY CONTINUES FARTHER WEST OVER CUBA...BUT IS LIKELY NOT CONNECTED TO THE WAVE. TROPICAL WAVE EXTENDS FROM 17N85W TO 10N86W MOVING W NEAR 15 KT 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 ALONG WITH DIFFLUENT FLOW ALOFT IS PRODUCING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS OVER MUCH OF COSTA RICA AND NICARAGUA...AS WELL AS NORTH OF HONDURAS FROM 16N-19N BETWEEN 82W-88W. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE COAST OF SENEGAL NEAR 14N17W TO 7N25W. THE ITCZ BEGINS NEAR 7N25W AND CONTINUES ALONG 5N34W 10N43W 6N54W. SCATTERED MODERATE CONVECTION IS FROM 6N-8N BETWEEN 18W-21W. ISOLATED MODERATE CONVECTION IS FROM 5N-9N BETWEEN 44W-55W. ...DISCUSSION... GULF OF MEXICO... AN UPPER LEVEL LOW CONTINUES TO IMPACT THE GULF OF MEXICO CENTERED OVER LOUISIANA NEAR 31N91W. A BROAD AREA OF DIFFLUENCE ALOFT SPREADS FROM THE YUCATAN PENINSULA ACROSS THE EASTERN GULF. THIS IS WHERE MOIST CONDITIONS ARE PRESENT ALONG WITH BROAD LOW-LEVEL TROUGHING. A SURFACE TROUGH AXIS EXTENDS ALONG 31N86W 27N91W 24N97W. SCATTERED SHOWERS/THUNDERSTORMS ARE ALONG THE WEST COAST OF THE YUCATAN PENINSULA. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS COVERS A GOOD PORTION OF THE EASTERN GULF NORTH OF 24N EAST OF 90W. STRONG SHOWERS/THUNDERSTORMS ARE ALSO OVER THE CENTRAL FLORIDA PENINSULA FROM 27N-29N BETWEEN 81W-83W. A FEW ISOLATED SHOWERS/THUNDERSTORMS ARE ALSO OVER PORTIONS OF THE WESTERN GULF NEAR THE SURFACE TROUGH AXIS AND ALONG THE TEXAS COAST. THE BROAD SURFACE TROUGH WILL CONTINUE TO DRIFT NORTHWEST OVER THE NEXT DAY. THE UPPER LEVEL LOW WILL ALSO LIFT NORTH BUT WILL CONTINUE TO PROVIDE DIFFLUENT FLOW OVER THE GULF...WHICH WILL LIKELY LEAD TO MORE SHOWER/THUNDERSTORM ACTIVITY. MOISTURE ASSOCIATED WITH A SURFACE TROUGH CURRENTLY OVER THE BAHAMAS WILL ALSO BRING INCREASED ACTIVITY TO THE SE GULF OVER THE WEEKEND. CARIBBEAN SEA... UPPER LEVEL RIDGING COVERS MUCH OF THE WESTERN CARIBBEAN WITH AXIS EXTENDING FROM HONDURAS TOWARDS FLORIDA. THIS PATTERN IS PROVIDING NORTHERLY FLOW OVER THE WESTERN PART OF THE AREA DRAWING MOISTURE SOUTH FROM THE GULF OF MEXICO. A TROPICAL WAVE IS ALSO IN THIS AREA OVER CENTRAL AMERICA LEADING TO SCATTERED SHOWERS/ISOLATED THUNDERSTORMS OVER MUCH OF THE NW CARIBBEAN...NICARAGUA...AND COSTA RICA. STRONG SHOWERS/THUNDERSTORMS ARE ALSO OVER MUCH OF CUBA. A SECOND TROPICAL WAVE IS APPROACHING JAMAICA ENHANCING A CLUSTER OF SHOWERS/THUNDERSTORMS JUST NE OF THE ISLAND. THIS WAVE MAY ALSO BE CONTRIBUTING TO ACTIVITY OVER CUBA. THE REMAINDER OF THE BASIN IS UNDER MOSTLY FAIR CONDITIONS DUE TO DRY AIR ALOFT AROUND A WEAK AND BROAD UPPER LOW NEAR 11N72W. BOTH WAVES ARE EXPECTED TO CONTINUE WESTWARD OVER THE NEXT 24 HOURS MAINTAINING MOIST CONDITIONS OVER THE WESTERN CARIBBEAN. HISPANIOLA... DRY AIR HAS MOVED OVER HISPANIOLA LIMITING ANY LARGE AREA OF SHOWERS OR THUNDERSTORMS. A FEW SMALL CLUSTERS HAVE POPPED UP THROUGHOUT THE AFTERNOON HOURS WITH NO ACTIVITY CURRENTLY PRESENT. A DRY AIR MASS WILL CONTINUE TO BRING FAIR WEATHER TO THE ISLAND FOR THE NEXT COUPLE OF DAYS. ATLANTIC OCEAN... MOISTURE ASSOCIATED WITH AN UPPER LEVEL LOW/SURFACE TROUGH IN THE GULF OF MEXICO CONTINUES AROUND AN UPPER LEVEL RIDGE ALONG 83W CONTINUING INTO THE FAR WEST ATLC. NO SHOWERS APPEAR TO BE PRESENT AT THIS TIME. A SURFACE TROUGH...CUT OFF PORTION OF A TROPICAL WAVE...CONTINUES TO MOVE THROUGH THE BAHAMAS ALONG 25N72W TO 20N76W. ISOLATED SHOWERS AND POSSIBLE THUNDERSTORMS ARE WITHIN 130 NM EITHER SIDE OF THE AXIS. WEAK AND HORIZONTALLY ELONGATED UPPER TROUGHING COVERS THE REMAINDER OF THE WEST ATLC INTO THE CENTRAL ATLC NEAR 30N. TO THE SOUTH...A BROAD UPPER RIDGE DOMINATES CENTERED NEAR 17N51W WITH A SECOND CENTER NEAR 19N35W. THE BROAD UPPER RIDGE SUPPORTS A PAIR OF SURFACE HIGH CENTERS. A 1025 MB HIGH COVERS THE CENTRAL ATLC NEAR 28N64W...WHILE A 1022 MB HIGH IS OVER THE EASTERN ATLC NEAR 29N32W. A DRY SAHARAN AIR LAYER ALSO COVERS MUCH OF THE TROPICAL ATLC EXTENDING FROM THE COAST OF AFRICA AROUND THE TROPICAL WAVE IN THE EASTERN ATLC TO NEAR 50W KEEPING CONDITIONS FAIR ACROSS THIS AREA. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON