000 AXNT20 KNHC 171747 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT SUN APR 17 2011 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTION OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND RADAR. BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...ITCZ... ITCZ AXIS IS ANALYZED ENTIRELY IN THE SOUTHERN HEMISPHERE WITHIN AN AREA FROM 04S-01S BETWEEN 07W-50W...INCLUDING PORTIONS OF NE BRAZIL. ISOLATED MODERATE CONVECTION IS FROM THE EQUATOR TO 03N BETWEEN 07W-12W...FROM THE EQUATOR TO 04N BETWEEN 24W-29W...AND FROM THE EQUATOR TO 03N BETWEEN 41W-48W. ...DISCUSSION... GULF OF MEXICO... ZONAL UPPER LEVEL WESTERLY FLOW IS ACROSS THE ENTIRE GULF BASIN THIS AFTERNOON ADVECTING MIDDLE TO UPPER LEVEL CLOUDINESS AND MOISTURE OVER PORTIONS OF THE WESTERN GULF. AT THE SURFACE...A FAIRLY WEAK FRONTAL BOUNDARY ANALYZED AS A COLD FRONT ACROSS THE SOUTHERN FLORIDA PENINSULA FROM LAKE OKEECHOBEE TO NAPLES THEN INTO THE SE GULF NEAR 25N84W CONTINUES TO MOVE E-SE. THE FRONT CONTINUES STATIONARY WESTWARD TO 24N90W AND BECOMES MORE DIFFUSE AS HIGH PRESSURE ANCHORED BY A 1020 MB HIGH CENTERED OVER CENTRAL ALABAMA SKIRTS THE NORTHERN GULF N OF 25N. MOSTLY LIGHT E-NE WINDS ARE NOTED ON RECENT SHIP AND BUOY OBSERVATIONS NW OF THE FRONTAL BOUNDARY WITH STRONGER SE WINDS TO 20 KT LOCATED OVER PORTIONS OF THE WESTERN GULF ON THE SOUTHWESTERN PERIPHERY OF THE RIDGE. BY EARLY MONDAY AS THE HIGH SHIFTS EASTWARD...THE SOUTHEASTERLY FLOW IS EXPECTED TO PERSIST THROUGH MID-WEEK WITH THE NEXT FRONTAL BOUNDARY APPROACHING THE COASTAL GULF PLAINS BY EARLY THURSDAY. CARIBBEAN SEA... ZONAL UPPER LEVEL WESTERLY FLOW IS NOTED ACROSS THE CARIBBEAN BASIN AS WELL THIS AFTERNOON ON THE NORTHERN PERIPHERY OF AN UPPER LEVEL RIDGE AXIS WHICH EXTENDS FROM THE TROPICAL ATLC NEAR 05N50W THROUGH 08N72W TO 10N98W IN THE E PACIFIC REGION. MOSTLY DRY AIR AND MODERATE SUBSIDENCE ALOFT IS MAINTAINING A RELATIVELY STABLE ATMOSPHERE WITH A LACK OF ANY ONGOING SIGNIFICANT DEEP CONVECTION. HOWEVER...ISOLATED LOW-TOPPED SHOWERS ARE OCCURRING SW OF HISPANIOLA FROM 16N-18N BETWEEN 71W-75W. E-NE TRADES IN THE RANGE OF 10 TO 20 KT CONTINUE ACROSS THE BASIN AND ARE EXPECTED TO PERSIST THROUGH EARLY WEDNESDAY. AN UPPER LEVEL LOW IS CENTERED NEAR 26N58W NE OF THE LEEWARD ISLANDS AND SUPPORTS A SURFACE TROUGH FROM 15N-25N ALONG 57W. GLOBAL MODELS ARE FORECASTING A MAJORITY OF THE ENERGY WITH THIS TROUGH TO SKIRT THE LEEWARD ISLANDS BRINGING AN INCREASED OPPORTUNITY FOR SCATTERED SHOWERS AND ISOLATED TSTMS BY LATE MONDAY INTO TUESDAY ACROSS PORTIONS OF THE NE CARIBBEAN... INCLUDING THE LEEWARD ISLANDS...US/UK VIRGIN ISLANDS...AND PUERTO RICO. ATLANTIC OCEAN... A DEEP LAYER TROUGH IS MOVING NE OF THE EASTERN U.S. AND SUPPORTS A COLD FRONT EXTENDING INTO THE DISCUSSION AREA NEAR 32N74W THEN SW TO THE FLORIDA PENINSULA COAST NEAR 27N80W. WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING WITHIN 75 NM EITHER SIDE OF THE FRONT N OF 29N...WITH PRE-FRONTAL ISOLATED SHOWERS ALSO NOTED ON SATELLITE IMAGERY OVER THE NW BAHAMAS FROM 24N-28N BETWEEN 77W-79W. FARTHER EAST...A MIDDLE TO UPPER LEVEL LOW IS ROTATING NEAR 26N57W AND SUPPORTS A SURFACE TROUGH EXTENDING FROM 15N-25N ALONG 57W. NEAR THE SOUTHERN EXTENT OF THE SURFACE TROUGH...ISOLATED SHOWERS ARE OCCURRING FROM 13N-19N BETWEEN 47W-59W...AND ARE EXPECTED TO CONTINUE DRIFTING WESTWARD WITH THE TROUGH THROUGH EARLY TUESDAY BRINGING INCREASED CHANCES OF PRECIPITATION TO THE LEEWARD ISLANDS. FARTHER NORTH IN THE VICINITY OF THE SURFACE TROUGH AND MUCH CLOSER TO THE STRONGER UPPER LEVEL DYNAMICS IN PLACE...SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING FROM 21N-31N BETWEEN 47W-59W. SOME OF THE STRONGER CONVECTIVE ACTIVITY IS LIKELY ENHANCED BY INCREASED DIFFLUENCE ALOFT DUE TO THE UPPER LEVEL LOW. LASTLY...ACROSS THE NE ATLC...A DEEP LAYER TROUGH IS LOCATED NW OF THE CANARY ISLANDS. A 1000 MB LOW IS CENTERED NEAR 31N23W WITH A SURFACE TROUGH AXIS EXTENDING FROM THE LOW ALONG 30N19W TO 28N19W TO 23N23W TO 21N31W. ISOLATED SHOWERS ARE WITHIN 60 NM EITHER SIDE OF THE TROUGH AXIS WITH MORE WIDELY SCATTERED SHOWER ACTIVITY LOCATED N OF 31N BETWEEN 14W-25W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN