000 AXNT20 KNHC 121737 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT SUN AUG 12 2012 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1700 UTC. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 26N34W TO 17N36W THROUGH A 1014 MB SURFACE LOW ALONG THE AXIS AT 21N36W MOVING W AT 20 KT. THE SATELLITE REPRESENTATION OF THE WAVE IS WELL-DEFINED WITH CLEAR LOW-LEVEL CYCLONIC FLOW AROUND THE LOW CENTER. THE SYSTEM ALSO COINCIDES WITH A CUT-OFF AREA OF DEEP MOISTURE PRESENT IN TOTAL PRECIPITABLE WATER IMAGERY. HOWEVER...DRY AIR AND DUST SURROUND THE WAVE LIMITING MOST DEEP CONVECTION. ONLY A SMALL AREA OF MODERATE CONVECTION IS W OF THE LOW CENTER FROM 21N-22N BETWEEN 37W-38W. TROPICAL WAVE...REMNANTS OF T.D. SEVEN...IS MOVING W AT 20 KT THROUGH THE EASTERN CARIBBEAN FROM 19N64W TO 11N66W. SATELLITE IMAGERY ALONG WITH SURFACE OBSERVATIONS INDICATE SHARP CYCLONIC FLOW AROUND THE AXIS. THE WAVE ALSO LIES UNDERNEATH THE BASE OF AN UPPER LEVEL TROUGH IN THE W ATLC...WHICH IS HELPING PRODUCE SHOWERS/THUNDERSTORMS NEAR THE WAVE. A CLUSTER OF STRONG CONVECTION IS FROM 14N-15N BETWEEN 63W-66W. SCATTERED MODERATE/STRONG CONVECTION IS FROM 12N-17N BETWEEN 66W-69W. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS W AFRICA TO THE COAST OF SENEGAL AT 15N17W WHERE IT CONTINUES ACROSS ATLC WATERS ALONG 11N23W 14N31W. THE ITCZ BEGINS FARTHER W AT 10N42W AND CONTINUES TO 10N59W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS NEAR THE COAST OF AFRICA FROM 8N-12N BETWEEN 15W-21W. ...DISCUSSION... GULF OF MEXICO... WEAK SURFACE RIDGING COVERS THE MAJORITY OF THE GULF OF MEXICO TODAY EXTENDS FROM THE W ATLC. SURFACE WINDS ARE LIGHT AND ANTI-CYCLONIC AROUND THE RIDGE. THE SURFACE RIDGE IS ALSO SUPPORTING MOSTLY FAIR WEATHER IN COMBINATION WITH DRY AIR ALOFT PRESENT ACROSS THE NW HALF OF THE GULF. HOWEVER...AN UPPER LEVEL TROUGH OVER THE EASTERN CONUS ALONG WITH AN UPPER LEVEL LOW OVER THE COAST OF MEXICO NEAR 24N98W ARE PROVIDING MOISTURE ACROSS THE SE HALF OF THE BASIN. THE UPPER TROUGH OVER THE EASTERN CONUS SUPPORTS A WEAK COLD FRONT THAT EXTENDS FROM THE FLORIDA PANHANDLE AT 31N84W ALONG 29N88W INTO LOUISIANA AT 30N91W. ISOLATED SHOWERS ARE ALONG THE FRONT. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE ALSO ACROSS THE SE GULF FROM THE YUCATAN CHANNEL TO CENTRAL FLORIDA. WEAK SURFACE RIDGING WILL REMAIN ACROSS THE BASIN WITH A CHANCE OF SHOWERS/THUNDERSTORMS REMAINING OVER THE SE HALF. CARIBBEAN SEA... AN UPPER LEVEL LOW OVER THE COAST OF MEXICO IN THE GULF OF MEXICO IS PROVIDING DIFFLUENCE ALOFT OVER THE NW CARIBBEAN SUPPORTING A FEW SHOWERS/THUNDERSTORMS OFF THE COAST OF THE YUCATAN PENINSULA AND THROUGH THE YUCATAN CHANNEL. STRONG SHOWERS/THUNDERSTORMS ACROSS ACROSS PORTIONS OF NICARAGUA...COSTA RICA...AND PANAMA NEAR THE MONSOON TROUGH THAT EXTENDS THROUGH SOUTHERN NICARAGUA TO NRN COLOMBIA ALONG 12N85W 10N79W 10N76W. THE CENTRAL CARIBBEAN IS MOSTLY DRY DUE TO DRY AIR ALOFT WRAPPING AROUND AN UPPER LEVEL RIDGE OVER THE FAR W ATLC...AND AN UPPER LEVEL INVERTED TROUGH WITH AXIS ALONG 71W. THE EASTERN CARIBBEAN IS BEING IMPACTED BY AN ACTIVE TROPICAL WAVE...REMNANTS OF T.D. SEVEN. THE WAVE AXIS IS WELL DEFINED AND IS SUPPORTING SHOWERS/THUNDERSTORMS WITHIN AT LEAST 200 NM EITHER SIDE OF THE AXIS. SOME OF THE ACTIVITY IS ENHANCED BY DIFFLUENCE ALOFT AROUND AN UPPER LEVEL TROUGH IN THE CENTRAL ATLC TO THE N. EXPECT SHOWERS/THUNDERSTORMS TO REMAIN NEAR THE WAVE AS IT MOVES WESTWARD INTO THE CENTRAL CARIBBEAN. ATLANTIC OCEAN... AN UPPER LEVEL RIDGE COVERS THE W ATLC SUPPORTING A 1022 MB HIGH NEAR 36N62W. HOWEVER...AN UPPER LEVEL TROUGH OVER THE EASTERN CONUS IS HELPING SUPPORT A FEW SHOWERS/THUNDERSTORMS N OF 29N BETWEEN 75W-78W...AND N OF 28N BETWEEN 69W-72W. A SECOND UPPER LEVEL TROUGH IS FARTHER E FROM 34N54W TO 18N63W SUPPORTING ISOLATED SHOWERS/POSSIBLE THUNDERSTORMS FROM 25N-29N BETWEEN 53W-58W. AN UPPER LEVEL RIDGE IS TO THE E CENTERED NEAR 24N47W SUPPORTING A 1026 MB HIGH CENTERED NEAR 33N35W. A WEAK UPPER LEVEL SHORTWAVE TROUGH IS ALONG 35N32W TO 26N39W SUPPORTING A FEW ISOLATED SHOWERS FROM 28N-31N BETWEEN 32W-37W. A TROPICAL WAVE IS TO THE SOUTH...BUT IS CAUSING NO SIGNIFICANT WEATHER AT THIS TIME. SEE TROPICAL WAVE SECTION FOR MORE DETAILS. VISIBLE SATELLITE IMAGERY INDICATES AN AREA OF DUST EXTENDS FROM THE COAST OF AFRICA AND IS WRAPPING AROUND THE N SIDE OF THE WAVE...WHICH IS LIKELY INHIBITING CONVECTION NEAR IT. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON