000 AXNT20 KNHC 182354 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT FRI MAY 18 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...TROPICAL WAVES... A TROPICAL WAVE IS CURRENTLY JUST OFFSHORE OF W AFRICA FROM 16N-7N ALONG 21W MOVING W NEAR 15 KTS. THE WAVE LIES WITHIN AN AREA OF ENHANCED MOISTURE EVIDENT IN TOTAL PRECIPITABLE WATER IMAGERY. THIS IS ALSO EVIDENT IN GOES-R DUST ENHANCEMENTS WHICH SHOW THE AREA OF DUST PUSHED TO THE N AND W OF THE WAVE AXIS. THIS DRY AIR SURROUNDING THE WAVE WILL LIKELY DIMINISH CONVECTION AS IT MOVES ACROSS THE ATLC. CURRENTLY SCATTERED MODERATE CONVECTION IS FROM 4N-8N BETWEEN 23W-25W. NUMEROUS STRONG CONVECTION IS ACROSS W AFRICA FROM 10N-14N BETWEEN 8W-17W...BARELY EMERGING OVER WATER. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS W AFRICA TO THE COAST OF GUINEA NEAR 11N15W. THE ITCZ BEGINS ON THE W OF SIDE OF THE TROPICAL WAVE AND EXTENDS ALONG 7N23W TO THE BRAZIL COAST AT 2N51W. BESIDES CONVECTION NEAR THE TROPICAL WAVE...NO DEEP CONVECTION IS ASSOCIATED WITH THE ITCZ ELSEWHERE. ...DISCUSSION... THE GULF OF MEXICO... A WEAK PRESSURE GRADIENT IS ACROSS THE GULF OF MEXICO TONIGHT SUPPORTING LIGHT WINDS. THE WIND PATTERN INDICATES VERY WEAK SURFACE RIDGING EXTENDS FROM A HIGH PRESSURE CENTER TO THE N NEAR THE GREAT LAKES REGION. DRY AIR ALOFT IN MAINLY ZONAL WLY FLOW IS HELPING MAINTAIN FAIR CONDITIONS WITH MOSTLY CLEAR SKIES ACROSS THE MAJORITY OF THE BASIN. HOWEVER...A SURFACE TROUGH EXTENDS FROM THE NW CARIBBEAN INTO THE SE GULF TO NEAR 23N87W SUPPORTING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ACROSS CUBA AND THE FLORIDA STRAITS. SCATTERED SHOWERS/THUNDERSTORMS ARE ALSO ACROSS MUCH OF S FLORIDA. EXPECT WEAK SURFACE RIDGING TO REMAIN OVER THE NRN GULF WITH SURFACE TROUGHING TO CONTINUE TO EXTEND FROM THE WRN CARIBBEAN INTO THE SE GULF SUPPORTING SHOWERS/THUNDERSTORMS ACROSS THIS AREA. THE CARIBBEAN SEA... MOIST CONDITIONS CONTINUE TO COVER MUCH OF THE YUCATAN PENINSULA...NRN CENTRAL AMERICA...AND THE NW CARIBBEAN ASSOCIATED WITH A WEAK 1009 MB SURFACE LOW NEAR 17N87W AND A SURFACE TROUGH EXTENDING FROM THE LOW CENTER TO 24N85W...AS OF 2100 UTC. STRONG SHOWERS/THUNDERSTORMS ARE OVER PORTIONS OF SW HONDURAS...NW NICARAGUA...AND ERN EL SALVADOR WITH SCATTERED SHOWERS/THUNDERSTORMS TO THE E FROM 13N-18N BETWEEN 81W-86W. A FEW ISOLATED SHOWERS/THUNDERSTORMS COVER THE REMAINDER OF THE NW CARIBBEAN INCLUDING MUCH OF CUBA. SCATTERED SHOWERS/THUNDERSTORMS ARE ALSO ACROSS HISPANIOLA LIKELY ASSOCIATED WITH DAYTIME HEATING. STRONG SHOWERS/THUNDERSTORMS COVER PORTIONS OF COSTA RICA AND PANAMA ASSOCIATED WITH THE E PACIFIC MONSOON TROUGH TO THE W. THE REMAINDER OF THE BASIN IS UNDER MOSTLY FAIR CONDITIONS DUE TO DRY AIR ALOFT BETWEEN AN UPPER LEVEL RIDGE CENTERED OVER HONDURAS...AND AN UPPER LEVEL TROUGH E OF THE LESSER ANTILLES. TRADEWIND FLOW OF 15-20 KTS IS PRESENT ACROSS MUCH OF THE BASIN. EXPECT BROAD LOW PRESSURE TO REMAIN OVER THE NW CARIBBEAN WITH MOIST CONDITIONS TO REMAIN OVER THAT AREA. THE ATLANTIC OCEAN... AN UPPER LEVEL TROUGH OVER THE NE CONUS AND W ATLC SUPPORTS A WEAK 1011 MB SURFACE LOW NEAR 32N76W...AS OF 2100 UTC. A COLD FRONT EXTENDS FROM THE LOW CENTER TO THE FLORIDA COAST ALONG 29N77W 28N81W. SCATTERED SHOWERS/THUNDERSTORMS ARE NEAR THE WRN EXTENT OF THE FRONT OVER FLORIDA. THE REMAINDER OF THE ACTIVITY IS FARTHER E NEAR THE STRONGEST AREA OF DIFFLUENCE ALOFT. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE FROM THE BAHAMAS TO N OF THE DISCUSSION AREA BETWEEN 67W-73W. AN UPPER LEVEL RIDGE EXTENDS FROM THE CARIBBEAN ACROSS HISPANIOLA TO NEAR 39N50W SUPPORTING A BROAD SURFACE RIDGE ACROSS THE CENTRAL AND ERN ATLC ANCHORED BY A 1034 MB HIGH NEAR 40N39W. OVER THE ERN ATLC...AN UPPER LEVEL TROUGH EXTENDS FROM E OF THE LESSER ANTILLES NEAR 11N59W TO 29N46W CONTINUING TOWARDS THE AZORES ISLANDS AT 38N26W. AN UPPER LEVEL RIDGE COVERS THE TROPICAL E ATLC CENTERED NEAR 13N30W. THE LAST VISIBLE SATELLITE IMAGES OF THE DAY ALONG WITH GOES-R DUST ENHANCEMENTS INDICATE THAT A LARGE AREA OF DUST EXTENDS FROM THE COAST OF AFRICA AROUND THE TROPICAL WAVE IN THE E ATLC AND CONTINUING TO 45W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON