000 AXNT20 KNHC 122346 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT WED JUN 12 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... A TROPICAL WAVE EXTENDS FROM 15N51W TO 4N53W MOVING W AT 20 KT. THE WAVE LIES WITHIN A SURGE OF DEEP LAYER MOISTURE PRESENT IN TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED MODERATE CONVECTION IS FROM 10N-12N BETWEEN 49W-52W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 7N-10N BETWEEN 53W-59W. A TROPICAL WAVE EXTENDS ACROSS PANAMA FROM 14N81W TO 7N82W MOVING W AT 10-15 KT. THE WAVE COINCIDES WITH A MAXIMUM IN DEEP LAYER MOISTURE PRESENT IN TOTAL PRECIPITABLE WATER THAT RESIDES OVER THE SW CARIBBEAN AND CONTINUES INTO THE EAST PACIFIC. SCATTERED MODERATE/STRONG CONVECTION IS FROM 8N-11N BETWEEN 78W- 83W. SIMILAR ACTIVITY CONTINUES UP CENTRAL AMERICA ACROSS COSTA RICA...NICARAGUA...AND HONDURAS. THIS ACTIVITY IS ENHANCED BY AN UPPER LEVEL TROUGH EXTENDING FROM EASTERN CUBA TO NEAR 12N83W. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE COAST OF GUINEA NEAR 11N15W TO 8N22W. THE ITCZ BEGINS NEAR 8N22W AND CONTINUES ALONG 6N38W 8N51W 7N60W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 6N-8N BETWEEN 35W-48W. ...DISCUSSION... THE GULF OF MEXICO... WEAK SURFACE RIDGING DOMINATES THE GULF OF MEXICO AROUND A 1021 MB HIGH NEAR 28N88W. THE RIDGE IS SUPPORTED BY AN UPPER LEVEL RIDGE CENTERED OVER CENTRAL MEXICO NEAR 20N99W. LIGHT ANTI- CYCLONIC WINDS ARE AROUND THE HIGH CENTER INCREASING UP TO 10-15 KT OVER THE WESTERN GULF. AN UPPER LEVEL TROUGH IS DIGGING SOUTH OVER THE FLORIDA PENINSULA ALONG 28N80W TO 25N88W. WHILE DRY AIR ALOFT AROUND THE NW SIDE OF THE UPPER TROUGH IS KEEPING THE NE GULF CLEAR...DIFFLUENCE AROUND THE SE SIDE OF THE TROUGH IS PRODUCING WIDESPREAD SHOWERS AND THUNDERSTORMS OVER THE SOUTHERN HALF OF THE FLORIDA PENINSULA AND THE FLORIDA STRAITS. A FEW ISOLATED SHOWERS ARE ALSO OVER THE WESTERN GULF AS MOIST AIR WRAPS AROUND THE UPPER RIDGE OVER MEXICO. SURFACE RIDGING WILL REMAIN THE DOMINANT FEATURE OVER THE NEXT COUPLE OF DAYS BEFORE A WEAK FRONTAL BOUNDARY MOVES THROUGH THE NE GULF OVER THE WEEKEND. SHOWERS AND THUNDERSTORMS WILL REMAIN LIKELY OVER THE WESTERN GULF...AND OVER SOUTHERN FLORIDA. THE CARIBBEAN SEA... MUCH OF THE CARIBBEAN WATERS ARE EXPERIENCING FAIR CONDITIONS DUE TO DRY AIR ALOFT BETWEEN AN UPPER LEVEL RIDGE OVER THE WESTERN GULF OF MEXICO...AND AN UPPER LEVEL TROUGH EXTENDING FROM EASTERN CUBA TO NEAR 12N83W. HOWEVER...HEAVY SHOWERS/THUNDERSTORMS ARE ACROSS JAMAICA...CUBA...AND HISPANIOLA AS A RESULT OF DAYTIME HEATING AND INSTABILITY. A TROPICAL WAVE MOVING THROUGH THE SW CARIBBEAN IS ALSO PRODUCING SHOWERS AND THUNDERSTORMS S OF 12N BETWEEN 77W-83W...AND ACROSS MUCH OF CENTRAL AMERICA. SEE TROPICAL WAVE SECTION ABOVE FOR MORE DETAILS. CONVECTION NEAR THE WAVE IS LIKELY BEING ENHANCED BY THE UPPER TROUGH. THE UPPER TROUGH IS PROVIDING MOIST AND SLIGHTLY DIFFLUENT FLOW ALOFT OVER THE EASTERN CARIBBEAN...WHICH IS LIKELY ENHANCING THE ACTIVITY OVER HISPANIOLA. A FEW ISOLATED LOW-LEVEL SHOWERS ARE ALSO EMBEDDED IN THE 15-20 KT TRADEWIND FLOW PRESENT THROUGHOUT THE AREA. STRONGER WINDS UP TO 25 KT ARE NEAR THE COAST OF COLOMBIA. MOIST CONDITIONS ARE EXPECTED TO REMAIN OVER THE SW CARIBBEAN AS THE WAVE TRACKS WESTWARD. THE UPPER TROUGH NEAR THE MONA PASSAGE WILL LIFT NORTH AS THE UPPER TROUGH OVER FLORIDA SINKS SOUTH AND WILL CONTINUE TO SUPPORT SHOWER ACTIVITY OVER THE NORTHERN CARIBBEAN ISLANDS. HISPANIOLA... A CLUSTER OF HEAVY SHOWERS/THUNDERSTORMS IS CURRENTLY OVER HAITI FROM 18N-20N BETWEEN 71W-73W...WHILE ISOLATED SHOWERS AND THUNDERSTORMS DOT THE REMAINDER OF THE ISLAND. THIS ACTIVITY IS DUE TO A COMBINATION OF DAYTIME HEATING AND INSTABILITY PRESENT ON MOST AFTERNOONS...AND DIFFLUENT FLOW ALOFT AROUND AN UPPER TROUGH EXTENDING FROM THE EASTERN CUBA TO THE SW CARIBBEAN. HEAVY CONVECTION FELL IN THIS SAME AREA YESTERDAY AFTERNOON. THE UPPER TROUGH WILL GRADUALLY LIFT NORTH OF THE NEXT 24 HOURS...BUT AN UPPER TROUGH OVER FLORIDA WILL SINK SOUTH AND CONTINUE TO PROVIDE MOIST AND DIFFLUENT FLOW OVER THE ISLAND INTO THE WEEKEND. THE ATLANTIC OCEAN... SCATTERED SHOWERS/THUNDERSTORMS ARE OVER THE FAR WESTERN ATLC WEST OF 75W S OF 28N ASSOCIATED WITH AN ELONGATED UPPER TROUGH DIPPING SOUTH OVER THE FLORIDA PENINSULA. A NARROW UPPER TROUGH IS ALSO TO THE EAST ALONG 69W PROVIDING DIFFLUENT FLOW ALOFT AND SUPPORTING ISOLATED SHOWERS FROM 24N-28N BETWEEN 62W-68W. THE REMAINDER OF THE AREA IS DOMINATED BY ONE LARGE AND BROAD SURFACE RIDGE ANCHORED BY A 1028 MB HIGH NEAR 30N39W. ALOFT...UPPER RIDGING IS ALONG 56W...AND 30W...WITH AN UPPER LEVEL TROUGH SANDWICHED BETWEEN THEM NEAR 47W. THE UPPER TROUGH SUPPORTS AN AREA OF HIGH CLOUDS AND POSSIBLE SHOWERS FROM 20N- 27N BETWEEN 43W-48W. THE LAST VISIBLE SATELLITE IMAGES OF THE DAY INDICATE A LARGE AREA OF SAHARAN DUST EXTENDS OFF THE COAST OF AFRICA AND CONTINUES TO NEAR 48W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON