000 AXNT20 KNHC 212342 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT TUE JUN 21 2011 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 2330 UTC. ...TROPICAL WAVES... A TROPICAL WAVE MOVED OFF THE WEST COAST OF AFRICA THIS EARLY AFTERNOON...NOW ANALYZED FROM 16N17W TO 10N18W MOVING W AT ABOUT 10-15 KT. THIS WAVE COINCIDES WITH A SURGE OF DEEP MOISTURE EVIDENT ON TOTAL PRECIPITABLE WATER IMAGERY. A BROAD AREA OF SCATTERED MODERATE CONVECTION SURROUNDS THE WAVE E OF 22W FROM 5N-15N. TROPICAL WAVE IN THE TROPICAL ATLC IS ANALYZED FROM 15N46W TO 7N47W MOVING W NEAR 10 KT. THE WAVE IS EMBEDDED IN A SURGE OF MOISTURE INDICATED BY THE TOTAL PRECIPITABLE WATER IMAGERY. AN INVERTED-V PATTERN SIGNATURE IS NOTICED ON THE LOW-MID LEVEL CLOUD PATTERN. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS WITHIN 150 NM ON EITHER SIDE OF THE WAVE AXIS. MOISTURE FROM THIS TROPICAL WAVE WILL REACH THE N TROPICAL ATLC EARLY WED. THIS WAVE WILL MOVE INTO THE E CARIBBEAN EARLY THU. TROPICAL WAVE IS INLAND OVER WESTERN VENEZUELA ALONG 71W S OF 13N MOVING W NEAR 10 KT. THE CONVECTION ASSOCIATED TO THIS WAVE REMAINS INLAND. THIS WAVE WILL BECOME ABSORBED INTO THE EASTERN EXTENT OF THE MONSOON TROUGH OVER THE SW CARIBBEAN ONCE IT MOVES OFF THE WESTERN COAST OF COLOMBIA IN THE NEXT 12 HOURS. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH REMAINS INLAND ACROSS WEST AFRICA. THE ITCZ STARTS W OF THE TROPICAL WAVE ALONG 10N20W 5N30W 7N40W TO THE COAST OF SOUTH AMERICA NEAR 5N52W. SCATTERED MODERATE CONVECTION IS WITHIN 80 NM ON EITHER SIDE OF THE ITCZ AXIS BETWEEN 23W-48W. ...DISCUSSION... GULF OF MEXICO... AN UPPER LEVEL RIDGE OF HIGH PRESSURE COVERS THE BASIN THIS EVENING WITH VERY DRY AIR ALOFT AND STRONG SUBSIDENCE NOTICED ON WATER VAPOR IMAGERY. THIS ENVIRONMENT IS KEEPING THE DISCUSSION AREA UNDER FAIR WEATHER CONDITIONS. SURFACE RETURN FLOW UP TO 15 KT IS OBSERVED OVER THE ENTIRE BASIN...CARRYING A FEW ISOLATED SHOWERS AND POSSIBLE THUNDERSTORMS MOVING N ACROSS THE CENTRAL BASIN BETWEEN 87W-90W. COMPUTER MODELS SUGGEST CONDITIONS WILL REMAIN SIMILAR OVER THE NEXT 24 HOURS WITH SOME WEAK CONVECTION DEVELOPING IN THE SW-W BASIN DURING THE FORECAST PERIOD. CARIBBEAN SEA... LAST VISIBLE SATELLITE PICTURES OF THE DAY INDICATED SCATTERED MODERATE TO HEAVY SHOWERS AND THUNDERSTORMS OVER THE FAR SW BASIN S OF 13N W OF 78W...DUE TO AN EXTENSION OF THE MONSOON TROUGH ANALYZED ACROSS CENTRAL AMERICA OVER PANAMA TO THE NORTHERN COAST OF COLOMBIA. OTHERWISE...FAIR WEATHER CONDITIONS ARE OBSERVED ACROSS THE REMAINDER OF THE DISCUSSION AREA. MARINE OBS INDICATE TRADE WIND FLOW 15-20 KT ACROSS THE AREA...GUSTING TO 25 KT ALONG THE COAST OF COLOMBIA. THIS PATTERN IS EXPECTED TO CONTINUE OVER THE NEXT 24 HOURS WITH SHALLOW MOISTURE EMBEDDED IN THE TRADE WIND FLOW PRODUCING ISOLATED WEAK SHOWERS. THE CONVECTION IN THE SW BASIN IS EXPECTED TO CONTINUE DURING THE FORECAST PERIOD. ATLANTIC OCEAN... WATER VAPOR IMAGERY INDICATES AN UPPER LEVEL SHORTWAVE/TROUGH MOVING ACROSS THE W ATLC N OF THE DISCUSSION AREA...SUPPORTING A LOW PRESSURE SYSTEM NEAR 34N66W. THE ASSOCIATED COLD FRONT REMAINS N OF THE DISCUSSION AREA. HOWEVER...THIS BOUNDARY IS EXPECTED TO ENTER THE AREA W OF 65W OVER THE NEXT 3-6 HOURS. THIS SAME UPPER LEVEL FEATURE ALSO SUPPORTS AN AREA OF SCATTERED SHOWERS AND POSSIBLE THUNDERSTORMS NE OF THE BAHAMAS FROM 22N-27N BETWEEN 69W-73W. AS THE UPPER TROUGH CONTINUES TO MOVE E...AN UPPER LEVEL RIDGE WILL MOVE INTO THE WESTERN ATLC PROMOTING FAIR WEATHER ACROSS THIS REGION. OTHERWISE...MOST OF THE ATLC WITHIN THE DISCUSSION AREA IS DOMINATED BY A BROAD UPPER LEVEL RIDGE...ANCHORED BY A PAIR OF SURFACE HIGHS IN THE CENTRAL ATLC...A 1021 MB AROUND 26N51W...AND A 1024 MB NEAR 32N34W RESPECTIVELY. WHILE THE 1021 MB HIGH IS EXPECTED TO REMAIN STATIONARY OVER THE NEXT 24 HOURS...TH LATTER WILL SHIFT NE OUT OF THE AREA DURING THE FORECAST PERIOD. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ GARCIA