000 AXNT20 KNHC 202350 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT WED APR 20 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 06N10W 01N16W CROSSING THE EQUATOR NEAR 20W THEN ALONG 02S29W 04S39W. WIDELY SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS FROM THE EQUATOR TO 07N BETWEEN 12W-27W. ...DISCUSSION... GULF OF MEXICO... WATER VAPOR IMAGERY THIS EVENING INDICATES RELATIVELY DRY AIR ALOFT WITHIN WESTERLY FLOW. THIS UPPER LEVEL PATTERN IS PROVIDING FOR RATHER BENIGN WEATHER AT THE SURFACE AS A 1023 MB HIGH IS CENTERED OVER THE FLORIDA PANHANDLE NEAR 30N84W. E-SE SURFACE WINDS IN THE RANGE OF 10 TO 20 KT ARE ACROSS MUCH OF THE GULF ON THE SOUTHWESTERN PERIPHERY OF THE SURFACE HIGH. WHILE MOST OF THE GULF REMAINS UNDER RELATIVELY CLEAR SKIES...THE LAST FEW VISIBLE SATELLITE IMAGES OF THE DAY SHOW THE ADVECTION OF SMOKE ORIGINATING IN SOUTHERN MEXICO...THE YUCATAN PENINSULA... AND CENTRAL AMERICA FROM SEVERAL WILDFIRES. LAND-BASED OBSERVATIONS ACROSS THE YUCATAN PENINSULA AND ALONG THE TEXAS AND LOUISIANA GULF COASTS AS WELL AS A FEW OFFSHORE OIL RIGS IN THE NW GULF SHOW REDUCED VISIBILITIES IN SMOKE AND HAZE. THE S-SE WINDS ARE EXPECTED TO PERSIST THROUGH THE WEEKEND. CARIBBEAN SEA... WEST-SOUTHWESTERLY UPPER LEVEL FLOW IS ACROSS A MAJORITY OF THE CARIBBEAN SEA ON THE NORTHERN PERIPHERY OF AN UPPER LEVEL RIDGE WITH AXIS EXTENDING FROM EASTERN VENEZUELA NEAR 07N62W TO NORTHERN COSTA RICA NEAR 10N84W. MOSTLY DRY AIR AND AN OVERALL SUBSIDENT ATMOSPHERE IS NOTED ON WATER VAPOR IMAGERY AND IS FURTHER SUPPORTED IN VISIBLE IMAGERY AS THE BASIN LACKS ANY SIGNIFICANT AREAS OF DEEP CONVECTION OR ORGANIZED SHOWER ACTIVITY THIS EVENING. LIGHT TO MODERATE NE TO E TRADES ARE EXPECTED TO PERSIST AS SURFACE TROUGHING MEANDERS NORTH OF THE LEEWARD ISLANDS THROUGH LATE SATURDAY. ATLANTIC OCEAN... ACROSS THE W ATLC...A 1010 MB LOW IS CENTERED NEAR 23N61W WITH A SURFACE TROUGH EXTENDING NE FROM THE LOW TO 26N56W. SATELLITE IMAGERY CONTINUES TO INDICATE THAT UPPER LEVEL SHEAR IS AFFECTING THE ABILITY OF THE LOW TO GATHER ANY CONVECTIVE ORGANIZATION THIS EVENING. THIS IS PRIMARILY DUE TO AN UPPER LEVEL LOW CENTERED TO THE NW OF THE SURFACE LOW NEAR 28N66W WHICH IS PROVIDING FOR A RATHER LARGE AREA OF MIDDLE TO UPPER LEVEL DIFFLUENCE EAST OF THE UPPER LEVEL LOW. SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING FROM 22N-29N BETWEEN 50W-64W. THIS SYSTEM CONTINUES TO CREATE AN INCREASED PRESSURE GRADIENT ACROSS THE W ATLC BETWEEN 50W-70W AS THE SUBTROPICAL RIDGE AXIS EXTENDS FROM A STRONG 1030 MB HIGH CENTERED NEAR 36N45W TO BERMUDA NEAR 32N65W TO THE NORTHERN FLORIDA PENINSULA COAST NEAR JACKSONVILLE AT 30N81W. A GALE WARNING REMAINS IN EFFECT WITHIN 300 NM OF THE LOW IN THE NORTHERN QUADRANT. AN EARLIER ASCAT PASS FROM 20/1326 UTC DEPICTED THIS WIND FIELD SHOWING E-NE WINDS IN THE 25 TO 35 KT RANGE. ELSEWHERE...THE REMAINDER OF THE ATLC E OF 50W IS UNDER THE INFLUENCE OF THE SUBTROPICAL RIDGE ANCHORED BY THE 1030 MB HIGH NORTH OF THE AREA PREVIOUSLY MENTIONED. A COLD FRONT IS ANALYZED INTO THE FAR NE CORNER OF ATLC FROM 32N10W TO 27N17W. IT IS EXPECTED TO CONTINUE MOVING EASTWARD WITH POSSIBLE SHOWERS ACROSS COASTAL MOROCCO AND NW WESTERN SAHARA. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN