000 AXNT20 KNHC 010555 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT SUN MAY 01 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0515 UTC. ...ITCZ... ITCZ AXIS IS FROM 04N08W CROSSING THE EQUATOR NEAR 18W THEN ANALYZED IN THE SOUTHERN HEMISPHERE ALONG 03S25W 01S34W AND INTO NE BRAZIL NEAR 02S43W. SCATTERED STRONG CONVECTION IS FROM 01N-04N BETWEEN 18W-26W. ...DISCUSSION... GULF OF MEXICO... AN UPPER LEVEL RIDGE AXIS EXTENDS OVER EASTERN MEXICO FROM 20N99W TO 30N94W AND NORTHEASTWARD OVER THE SE CONUS. MOSTLY DRY AIR AND OVERALL SUBSIDENCE IS ASSOCIATED WITH NW FLOW ALOFT OVER MUCH OF THE GULF BASIN THIS EVENING. THIS UPPER LEVEL FEATURE IS SUPPORTIVE OF A SURFACE RIDGE EXTENDING FROM THE W ATLC NEAR 30N80W TO THE NW GULF NEAR 28N95W WITH E TO SE WINDS IN THE RANGE OF 10 TO 20 KT THAT ARE EXPECTED TO INCREASE SLIGHTLY OVER THE WESTERN GULF W OF 90W THROUGH SUNDAY AFTERNOON. AN APPROACHING FRONT...CURRENTLY DRAPED ACROSS CENTRAL TEXAS...IS FORECAST TO EMERGE OFF THE GULF COAST AS A COLD FRONT LATE MONDAY MORNING WITH STRONG NORTHERLY WINDS EXPECTED WEST OF THE FRONT. CARIBBEAN SEA... WEAK AND BROAD UPPER LEVEL TROUGHING IS LOCATED OVER THE NW CARIBBEAN WHICH IS PROVIDING FOR MOSTLY SOUTHWESTERLY FLOW ALOFT AND INCREASED MIDDLE TO UPPER LEVEL MOISTURE ACROSS THE BASIN S OF 18N E OF 83W. AT THE SURFACE...MODERATE TO FRESH EASTERLY TRADEWIND FLOW CONTINUES AND IS EXPECTED TO PERSIST OVER THE NEXT FEW DAYS. EMBEDDED WITHIN THIS LOW-LEVEL FLOW...A SURFACE TROUGH ANALYZED FROM 13N68W OVER CENTRAL PUERTO RICO TO 19N66W IS PROVIDING FOCUS FOR LOW-LEVEL CONVERGENCE AND ISOLATED SHOWERS FROM 14N-19N BETWEEN 60W-70W. RECENT SCATTEROMETER DATA FROM EARLIER EVENING WINDSAT AND ASCAT PASSES CAPTURED THE SURFACE TROUGH AXIS AND A RELATIVELY STRONGER WIND FIELD WITHIN 120 NM EITHER SIDE OF THE AXIS N OF 15N. THE REMAINDER OF THE CARIBBEAN IS EXPERIENCING MOSTLY CLEAR SKIES WITH NO SIGNIFICANT CONVECTION NOTED ON SATELLITE IMAGERY. ATLANTIC OCEAN... AN UPPER LEVEL TROUGH AXIS EXTENDS OVER THE W ATLC FROM 40N65W INTO THE DISCUSSION AREA NEAR 32N70W THEN S-SW ACROSS WESTERN CUBA NEAR 22N80W AND INTO THE NW CARIBBEAN SEA. THIS UPPER LEVEL FEATURE SUPPORTS A COLD FRONT EXTENDING INTO THE SW NORTH ATLC NEAR BERMUDA THEN STRETCHING SW TO THE CENTRAL BAHAMAS NEAR 25N78W. ISOLATED SHOWERS ARE OCCURRING WITHIN 90 NM EITHER SIDE OF THE FRONT WHILE LOW-LEVEL CONVERGENCE EAST OF THE FRONT IS GENERATING ISOLATED SHOWERS N OF 27N BETWEEN 60W-70W. THE FRONT IS FORECAST TO SHIFT NE OF 28N65W BY LATE SUNDAY WITH LIGHT EASTERLY FLOW EXPECTED OVER THE SW NORTH ATLC W OF 70W. THE REMAINDER OF THE CENTRAL AND EASTERN ATLC THIS EVENING IS UNDER THE INFLUENCE OF A VERY BROAD SURFACE RIDGE ANCHORED BY A 1028 MB HIGH CENTERED NEAR 36N48W. MEANWHILE...A VIGOROUS UPPER LEVEL LOW CONTINUES TO SPIN NORTH OF THE CANARY ISLANDS NEAR 34N14W AND SUPPORTS A COLD FRONT EXTENDING INTO THE NE ATLC ALONG 32N10W TO 25N15W TO 22N20W. A RECENT 30/2250 UTC ASCAT PASS DEPICTED STRONG W-NW WINDS IN THE RANGE OF 20 TO 30 KT N OF 25N BETWEEN 13W-23W WITH THIS PARTICULAR FRONTAL BOUNDARY. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN