000 AXNT20 KNHC 200545 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT SUN MAY 20 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0515 UTC. ...SPECIAL FEATURES... TROPICAL STORM ALBERTO IS CENTERED NEAR 31.8N 78.8W AT 20/0600 UTC OR ABOUT 91 NM SE OF CHARLESTON SOUTH CAROLINA AND ABOUT 126 NM E OF SAVANNAH GEORGIA MOVING SW AT 5 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 998 MB. MAXIMUM SUSTAINED WIND SPEED IS 45 KT WITH GUSTS TO 55 KT. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC FOR MORE DETAILS. HEAVY SHOWERS WITH SCATTERED THUNDERSTORMS ARE FROM 32N-34N BETWEEN 76W-80W INCLUDING THE COAST OF SOUTH CAROLINA WITH SCATTERED SHOWERS FROM 31N-32N BETWEEN 77W-81W. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 10N29W TO 4N31W MOVING WSW NEAR 15 KT. WAVE IS EMBEDDED WITHIN A SURGE OF DEEP LAYERED MOISTURE AS EVIDENT IN TOTAL PRECIPITABLE WATER IMAGERY. HOWEVER...NO DEEP CONVECTION IS OBSERVED. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH EXTENDS INTO THE E TROPICAL OFF W AFRICA NEAR 7N11W TO 2N17W WHERE THE ITCZ AXIS CONTINUES ALONG 1N21W TO 4N30W THEN RESTARTS W OF THE TROPICAL WAVE NEAR 4N33W CONTINUING ALONG 5N42W TO INLAND OVER SOUTH AMERICA NEAR 2N47W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE WITHIN 90 NM OF LINE FROM 4N4W TO 2N16W. ...DISCUSSION... GULF OF MEXICO... AN UPPER RIDGE AXIS EXTENDS ALONG THE COAST OF MEXICO AND TEXAS FROM AN UPPER HIGH IN THE E PACIFIC REGION COVERING THE W GULF WHILE AN UPPER TROUGH COVERS THE E GULF INTO THE W ATLC. A WEAK SURFACE RIDGE EXTENDS FROM THE OHIO VALLEY OVER THE NW GULF TO THE W BAY OF CAMPECHE WITH STRONG SUBSIDENCE AND DRY STABLE AIR COVERING ALL BUT THE STRAITS OF FLORIDA. A SURFACE TROUGH EXTENDS AT 20/0300 UTC FROM 25N83W THROUGH THE YUCATAN CHANNEL NEAR 21N86W INTO THE W CARIBBEAN WITH SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS S OF 25N E OF 86W TO OVER CUBA...THE FLORIDA KEYS AND THROUGH THE STRAITS OF FLORIDA. THE REMAINDER OF THE GULF IS UNDER MOSTLY CLEAR SKIES. THE SURFACE TROUGH WILL REMAIN NEARLY STATIONARY THROUGH THU. CARIBBEAN SEA... BROAD UPPER RIDGE OVER THE W GULF OF MEXICO COVERS THE ENTIRE CARIBBEAN BASIN WITH A RIDGE AXIS EXTENDING FROM OVER CENTRAL AMERICA NEAR 14N84W TO ACROSS HISPANIOLA NEAR 18N71W. A SURFACE TROUGH EXTENDS FROM THE GULF OF HONDURAS NEAR 16N87W THROUGH THE YUCATAN CHANNEL INTO THE GULF OF MEXICO NEAR 21N86W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE OVER THE W CARIBBEAN W OF A LINE FROM CUBA NEAR 20N77W TO THE TIP OF NICARAGUA/HONDURAS. A SURFACE TROUGH IS OVER THE W ATLC TO OVER THE E TIP OF CUBA GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS OVER THE WINDWARD PASSAGE AND HISPANIOLA. MODERATE TO FRESH EASTERLY TRADE WINDS ARE ACROSS THE BASIN USHERING IN SOME ISOLATED LOW LEVEL SHOWERS ACROSS THE E CARIBBEAN E OF 70W TO OVER THE LESSER ANTILLES. THE TRADE WINDS WILL PERSIST THROUGH THU. THE SURFACE TROUGH WILL REMAIN NEARLY STATIONARY THROUGH THU. ATLANTIC OCEAN... TROPICAL STORM ALBERTO IS THE PRIMARY FOCUS TONIGHT...SEE SPECIAL FEATURES ABOVE. THE UPPER TROUGH OVER THE E GULF OF MEXICO EXTENDS INTO THE W ATLC N OF 22N W OF 70W SUPPORTING A SURFACE TROUGH THAT EXTENDS AT 20/0300 UTC FROM 29N75W TO THE FLORIDA COAST NEAR FORT LAUDERDALE WITH SCATTERED SHOWERS/ ISOLATED THUNDERSTORMS WITHIN 60 NM OF LINE FROM 31N74W TO 27N79W. A SECOND SURFACE TROUGH EXTENDS FROM 26N72W ACROSS THE S BAHAMA ISLANDS TO THE E TIP OF CUBA NEAR 20N75W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 180 NM EITHER SIDE OF THE TROUGH AXIS. AN UPPER RIDGE AXIS IS E OF THE ABOVE UPPER TROUGH EXTENDING FROM THE BROAD UPPER RIDGE OVER THE CARIBBEAN NEAR 18N71W TO BEYOND 32N62W. CLUSTERS OF SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS ARE WITHIN 200 NM OF LINE FROM 26N71W TO BEYOND 32N66W. A VERY BROAD SURFACE RIDGE DOMINATES THE REMAINDER OF THE ATLC N OF 15N BETWEEN AFRICA AND 70W ANCHORED BY A 1036 MB HIGH ABOUT 500 NM W OF THE AZORES. THE SURFACE TROUGH S OF ALBERTO WILL REMAIN IN THE W ATLC THROUGH TUE WHILE THE SECOND SURFACE TROUGH WILL REMAIN THROUGH MON THEN DISSIPATE. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ PAW