000 AXNT20 KNHC 192354 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SAT MAY 19 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. ...SPECIAL FEATURES... TROPICAL STORM ALBERTO IS CENTERED NEAR 32.2N 77.9W AT 19/2250 UTC OR ABOUT 115 NM ESE OF CHARLESTON SOUTH CAROLINA AND ABOUT 105 NM S OF CAPE FEAR NORTH CAROLINA MOVING SW AT 03 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 995 MB. MAXIMUM SUSTAINED WIND SPEED IS 50 KT WITH GUSTS TO 60 KT. THE AREAL EXTENT OF ALBERTO IS FAIRLY SMALL WITH SCATTERED MODERATE CONVECTION OCCURRING FROM 31N-34N BETWEEN 76W-80W. SEE LATEST NHC FORECAST/ ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC FOR MORE DETAILS...AS WELL AS THE LATEST NHC UPDATE UNDER AWIPS/WMO HEADERS MIATCUAT1/WTNT61 KNHC. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 04N31W TO 10N27W MOVING W NEAR 20 KT. THE WAVE IS EMBEDDED WITHIN A BROAD AREA OF DEEP LAYERED MOISTURE AS EVIDENT IN TOTAL PRECIPITABLE WATER IMAGERY. ALSO... LOW-LEVEL CYCLONIC WIND FLOW WAS NOTED IN THE VICINITY OF THE WAVE AXIS ON AN EARLIER MORNING OSCAT PASS AROUND 19/1400 UTC. NO DEEP CONVECTION IS NOTED ON SATELLITE IMAGERY...HOWEVER A FEW ISOLATED LOW-TOPPED SHOWERS ARE POSSIBLE FROM 04N-09N BETWEEN 28W-32W. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 05N09W TO 02N18W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 02N18W TO 03N23W TO 07N30W TO 04N43W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS FROM 03N-06N BETWEEN THE PRIME MERIDIAN AND 04W. ...DISCUSSION... GULF OF MEXICO... WEST-NORTHWESTERLY UPPER LEVEL FLOW DOMINATES ACROSS THE GULF BASIN THIS EVENING AS WATER VAPOR IMAGERY INDICATES VERY DRY AIR AND OVERALL SUBSIDENCE REMAINS ALOFT. THIS IS SUPPORTIVE OF A SURFACE RIDGE AXIS EXTENDING FROM THE SE CONUS ACROSS THE NORTH-CENTRAL AND WESTERN GULF FROM 30N89W TO 20N97W. FARTHER EAST...AN UPPER LEVEL LOW IS CENTERED OVER EASTERN GEORGIA NEAR 33N81W AND EXTENDS BROAD AND WEAK MIDDLE TO UPPER LEVEL TROUGHING ACROSS THE FAR NE GULF AND FLORIDA PENINSULA. SURFACE TROUGHING EXTENDS ACROSS MUCH OF THE SW NORTH ATLC WATERS W OF 76W SOUTHWESTWARD TO THE LOWER FLORIDA KEYS. LOW-LEVEL MOISTURE CONVERGENCE ALONG WITH MIDDLE TO UPPER LEVEL DIFFLUENCE IS PROVIDING FOR PLENTY OF MOISTURE AND INSTABILITY OVER THE SE GULF...FLORIDA STRAITS...AND SOUTHERN FLORIDA PENINSULA THIS EVENING. MOSAIC DOPPLER RADAR...SATELLITE IMAGERY...AND LIGHTNING DATA INDICATE WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS CONTINUE TO OCCUR OVER THESE AREAS SE OF A LINE FROM 27N82W TO 23N88W. THE SURFACE RIDGE IS FORECAST TO REMAIN NEARLY STATIONARY ACROSS THE CENTRAL AND WESTERN GULF THROUGH THE WEEKEND INTO MONDAY PROVIDING NE TO E WINDS IN THE RANGE OF 10 TO 20 KT. CARIBBEAN SEA... MUCH OF THE CARIBBEAN BASIN IS UNDER THE INFLUENCE OF THE EASTERN PERIPHERY OF AN UPPER LEVEL ANTICYCLONIC CIRCULATION CENTERED OVER EL SALVADOR NEAR 14N89W PROVIDING W-NW TO NORTHERLY UPPER LEVEL FLOW THIS EVENING. W OF 75W...UPPER LEVEL WIND SHEAR REMAINS MINIMAL AND UPPER LEVEL DIFFLUENCE CONTINUES TO BE MAXIMIZED BETWEEN 78W-90W. ALONG WITH A SURFACE TROUGH ANALYZED FROM WESTERN CUBA NEAR 23N84W INTO A 1009 MB LOW CENTERED IN THE GULF OF HONDURAS NEAR 17N87W...PLENTY OF DEEP LAYERED MOISTURE IS AVAILABLE FOR SCATTERED SHOWERS AND ISOLATED TSTMS OCCURRING OVER PORTIONS OF THE WESTERN CARIBBEAN W OF A LINE FROM 20N77W TO 11N84W...INCLUDING PORTIONS OF INLAND NICARAGUA AND HONDURAS. ISOLATED SHOWERS SPREAD FARTHER INLAND WESTWARD OVER BELIZE...EL SALVADOR...AND GUATEMALA. GLOBAL MODEL GUIDANCE SUGGESTS THIS SURFACE TROUGHING WILL REMAIN NEARLY STATIONARY OVER THE WESTERN CARIBBEAN THROUGH MUCH OF NEXT WEEK AND CONTINUE TO BRING INCREASED CHANCES OF HEAVY RAINFALL AND HIGHER PROBABILITIES OF LOCALIZED FLOODING ACROSS PORTIONS OF CENTRAL AMERICA. THE REMAINDER OF THE CARIBBEAN E OF 75W IS UNDER MOSTLY EAST-SOUTHEASTERLY SURFACE WINDS IN THE RANGE OF 15 TO 25 KT WITH ISOLATED SHOWERS OCCURRING N OF 16N E OF 75W. A FEW EMBEDDED ISOLATED TSTMS ARE ALSO OCCURRING OVER HISPANIOLA THIS EVENING. ATLANTIC OCEAN... TROPICAL STORM ALBERTO REMAINS JUST NORTH OF THE DISCUSSION AREA OFF THE SOUTH CAROLINA COAST...SEE ABOVE FOR DETAILS. ELSEWHERE OVER THE SW NORTH ATLC...WATER VAPOR IMAGERY INDICATES ADVECTION OF DEEP LAYERED TROPICAL MOISTURE DUE TO STRONG SOUTHWESTERLY FLOW ALOFT N OF 21N W OF 62W. BENEATH THE MIDDLE AND UPPER LEVEL MOISTURE...A SURFACE TROUGH IS ANALYZED FROM EASTERN CUBA NEAR 21N77W TO 28N73W. WHILE LOW-LEVEL MOISTURE CONVERGENCE IS MAXIMIZED IN THE VICINITY OF THE SURFACE TROUGH...A LARGE AREA OF SCATTERED SHOWERS AND WIDELY SCATTERED TSTMS IS OCCURRING OVER THE SW NORTH ATLC FROM 18N-31N BETWEEN 62W-80W...INCLUDING THE TURKS AND CAICOS...THE BAHAMAS...AND CUBA. THE SURFACE TROUGHING ACROSS THE SW NORTH ATLC IS FORECAST TO PERSIST THROUGH THE REMAINDER OF THE WEEKEND. GLOBAL MODEL GUIDANCE DIFFERS SLIGHTLY ON WHETHER A SURFACE LOW WILL DEVELOP IN THE VICINITY OF 30N70W BY LATE SUNDAY EAST OF TROPICAL STORM ALBERTO. THE GFS REMAINS MOST AGGRESSIVE MOVING THE LOW NORTH-NORTHEASTWARD THROUGH TUESDAY...WITH THE ECMWF AND UKMET SUGGESTING A WEAK LOW OR SURFACE TROUGHING REMAINING THE DOMINATE WEATHER FEATURE. FARTHER EAST...THE CENTRAL AND EASTERN ATLC IS UNDER THE INFLUENCE OF A BROAD SURFACE RIDGE ANCHORED BY A 1036 MB HIGH CENTERED W-SW OF THE AZORES NEAR 37N38W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN