000 AXNT20 KNHC 151041 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT FRI APR 15 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1015 UTC. ...ITCZ... ITCZ AXIS IS ANALYZED ALONG 05N09W 03N16W CROSSING THE EQUATOR NEAR 21W THEN TO 03S28W AND INTO NE BRAZIL NEAR 03S40W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS FROM THE EQUATOR TO 06N BETWEEN 17W-23W. ISOLATED MODERATE CONVECTION IS FROM 01N-05N BETWEEN 33W-41W. ...DISCUSSION... GULF OF MEXICO... W-NW FLOW ALOFT IS ACROSS MUCH OF THE GULF THIS MORNING BETWEEN AN UPPER LEVEL TROUGH ACROSS THE U.S. CENTRAL PLAINS AND AN UPPER LEVEL RIDGE CENTERED IN THE EAST PACIFIC REGION NEAR 06N90W. RECENT SHIP AND BUOY OBSERVATIONS INDICATE SOUTHERLY RETURN FLOW ACROSS THE ENTIRE BASIN WHICH IS EXPECTED TO PERSIST THROUGH THIS MORNING AHEAD OF THE NEXT COLD FRONT CURRENTLY ANALYZED FROM NE TEXAS TO WEST-CENTRAL TEXAS NEAR LUBBOCK. LOW STRATUS AND POSSIBLE AREAS OF DENSE FOG ARE OBSERVED ON SHORTWAVE INFRARED SATELLITE IMAGERY OVER THE NW GULF WATERS AND ALONG THE TEXAS AND LOUISIANA COASTS. THE COLD FRONT IS FORECAST TO EMERGE OFF THE TEXAS GULF COAST BY FRIDAY AFTERNOON. EASTWARD PROGRESSION OF THE FRONT THROUGH THE WEEKEND WILL ALLOW HIGH PRESSURE TO BUILD IN ACROSS THE WESTERN GULF THROUGH LATE SATURDAY. CARIBBEAN SEA... AN AMPLIFIED MIDDLE TO UPPER LEVEL TROUGH IS LOCATED OVER THE WESTERN CARIBBEAN WITH AXIS EXTENDING INTO THE BASIN FROM NE OF HISPANIOLA NEAR 20N68W S-SW THROUGH THE MONA PASSAGE TO NORTHERN COLOMBIA NEAR 09N76W. STRONG SUBSIDENCE AND DRY AIR ACCOMPANY THIS UPPER LEVEL FEATURE AND THESE FACTORS CONTINUE TO PROVIDE OVERALL CLEAR SKIES AND FAIR CONDITIONS ACROSS THE WESTERN AND CENTRAL CARIBBEAN W OF 68W THIS MORNING. EAST OF THE TROUGH AXIS HOWEVER...SW FLOW IS ADVECTING UPPER LEVEL MOISTURE ACROSS THE FAR EASTERN CARIBBEAN AND LESSER ANTILLES NE INTO THE TROPICAL NORTH ATLC. ISOLATED SHOWERS ARE OCCURRING E OF 66W WITH MOST OF THIS ACTIVITY FOCUSED IN THE VICINITY OF A SURFACE TROUGH ANALYZED FROM 12N65W TO 19N65W. ELSEWHERE...EASTERLY TRADES REMAIN FAIRLY LIGHT...WITH THE EXCEPTION OF STRONGER WINDS NEAR THE COAST OF COLOMBIA...DUE TO A RELAXED PRESSURE GRADIENT ACROSS THE ENTIRE BASIN. ATLANTIC OCEAN... A MIDDLE TO UPPER LEVEL TROUGH IS OVER THE W ATLC WITH AXIS ALONG 32N64W TO THE MONA PASSAGE NEAR 19N68W. THE UPPER LEVEL TROUGH SUPPORTS A DISSIPATING STATIONARY FRONT ANALYZED INTO THE DISCUSSION AREA NEAR 32N68W EXTENDING SW TO NEAR 28N72W. FRONTAL TROUGHING EXTENDS WEST TO THE FLORIDA PENINSULA NEAR DELRAY BEACH HOWEVER MUCH OF THE BOUNDARY W OF 73W HAS LOST ALL UPPER LEVEL SUPPORT. ISOLATED SHOWERS ARE WITHIN 30 NM EITHER SIDE OF THE STATIONARY FRONT...WHILE LINGERING ISOLATED LOW-TOPPED SHOWERS ARE OCCURRING OVER THE NW BAHAMAS FROM 25N-28N BETWEEN 76W-81W. A WEAK HIGH PRESSURE RIDGE LOCATED W OF THE FRONT IS EXPECTED TO PROVIDE LIGHT EASTERLY FLOW THROUGH LATE FRIDAY AS THE FRONT MOVES NE OF 30N68W. FARTHER EAST...AN UPPER LEVEL RIDGE ENCOMPASSES A LARGE PORTION OF THE CENTRAL ATLC BETWEEN 35W-60W THAT SUPPORTS A SURFACE RIDGE ANCHORED BY A 1030 MB HIGH CENTERED NEAR 40N41W. THE RIDGE AXIS EXTENDS FROM THE HIGH SW TO 27N65W. ON THE SOUTHERN PERIPHERY OF THE RIDGE...A SHEAR LINE IS ANALYZED FROM 18N53W TO 22N65W AS MOISTURE ASSOCIATED WITH THE TAIL END OF A REMNANT FRONTAL BOUNDARY DRIFTS WESTWARD PROVIDING ISOLATED SHOWERS FROM 14N-24N BETWEEN 54W-66W. FARTHER EAST...AN UPPER LEVEL LOW ROTATES NORTH OF THE DISCUSSION AREA NEAR 35N30W THAT SUPPORTS A COLD FRONT EXTENDING FROM 32N30W SW TO 28N39W. POSSIBLE ISOLATED SHOWERS ARE OCCURRING WITHIN 90 NM EITHER SIDE OF THE FRONT. AS THE UPPER LEVEL LOW REMAINS NEARLY STATIONARY OVER THE NEXT 24 TO 36 HOURS...A 1008 MB LOW CENTERED NEAR 30N21W IS FORECAST TO RETROGRADE WESTWARD SLIGHTLY AND INTENSIFY BY EARLY SATURDAY TO A 999 MB LOW CENTERED IN THE VICINITY OF 30N27W. STRONG WINDS ABOVE 20 KT ARE EXPECTED WITHIN 360 NM OF THE SOUTHWEST SEMICIRCLE OF THE LOW. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN