000 AXNT20 KNHC 262341 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST SAT FEB 26 2011 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...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND RADAR. BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2300 UTC. ...ITCZ... THE ITCZ AXIS IS ANALYZED FROM THE COAST OF LIBERIA NEAR 5N9W TO 4N20W TO 2N30W TO NE BRAZIL NEAR 3S45W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS FROM THE EQUATOR TO 3N BETWEEN 28W AND 35W. SIMILAR CONVECTION IS ALSO NOTED ALONG THE COASTS OF LIBERIA AND THE IVORY COAST FROM 2N-7N BETWEEN 6W-9W...NEAR THE EQUATOR AT 8W AND NEAR 2N14W. ...DISCUSSION... GULF OF MEXICO... HIGH PRES LOCATED OVER THE ATLANTIC OCEAN EXTENDS A RIDGE WWD ACROSS THE GULF REGION. A WEAK FRONTAL BOUNDARY REMAINS OVER N FLORIDA AND THE NE PORTION OF THE GULF. A FEW SHOWERS ARE NEAR THIS FEATURE WHICH WILL DISSIPATE TONIGHT AS IT LIFTS N. SLY RETURN FLOW OVER THE WESTERN GULF WILL INCREASE TO 20 KT LATE TONIGHT AHEAD OF A COLD FRONT FORECAST TO MOVE INTO THE NW GULF LATE SUN INTO MON. FRESH TO STRONG NLY WINDS AND BUILDING SEAS TO AROUND 8 FT ARE EXPECTED IN THE WAKE OF THE FRONT. THE REST OF THE GULF OF MEXICO IS ENJOYING MAINLY FAIR WEATHER AND LIGHT TO GENTLE BREEZE. A ZONAL FLOW TO THE N OF AN ANTICYCLONE ALOFT CENTERED OVER SE MEXICO AND GUATEMALA DOMINATES THE GULF. STRONG SUBSIDENCE ACCOMPANIES THIS UPPER LEVEL FEATURE AS EVIDENCED IN RECENT WATER VAPOR IMAGERY. WARM AND DRY CONDITIONS PREVAIL OVER SOUTH FLORIDA UNDER THE INFLUENCE OF A RIDGE ALOFT AND AT THE SURFACE. CARIBBEAN SEA... THE 1506 UTC ASCAT PASS SHOWED 20-30 KT TRADEWINDS OVER THE SOUTH CENTRAL CARIBBEAN WITH THE STRONGEST WINDS AS USUAL NEAR THE COAST OF COLOMBIA. FEW SHIP OBSERVATIONS ALSO CORROBORATED THESE WIND SPEEDS. HIGH PRES N OF AREA WILL CONTINUE TO PRODUCE FRESH TO STRONG TRADES ACROSS THE E AND CENTRAL CARIBBEAN THROUGH MON. FURTHER E...A SHEAR LINE...WHICH IS THE FINAL STAGE IN THE LIFE CYCLE OF A COLD FRONT OVER THE SUBTROPICS AND TROPICS... ENTERS THE CARIBBEAN SEA THROUGH THE WINDWARD ISLANDS THEN CONTINUES MAINLY WWD TO NEAR THE ABC ISLANDS. A WELL DEFINED BAND OF LOW/MID CLOUDS WITH EMBEDDED SHOWERS IS ASSOCIATED WITH THIS SYSTEM. LOW LEVEL MOISTURE RELATED TO THIS SHEAR LINE WILL CONTINUE TO ENHANCE SOME SHOWER ACTIVITY FROM THE WINDWARD ISLANDS TO THE ABC ISLANDS AND ACROSS NORTHERN VENEZUELA THROUGH SUN. NE WINDS OF 20-25 KT ARE NOTED TO THE N OF THE SHEAR LINE PER AN EARLIER ASCAT PASS. LOW LEVEL CONVERGENCE IS PRODUCING CLOUDINESS WITH EMBEDDED SHOWERS ALONG THE CARIBBEAN PLAINS OF NICARAGUA. PATCHES OF LOW-LEVEL MOISTURE ARE ALSO SEEN ACROSS THE WESTERN CARIBBEAN W OF 84W. ONE OF THEM IS MOVING ACROSS THE YUCATAN CHANNEL. IN THE UPPER LEVELS...A WEST-TO-EAST RIDGE STRETCHES FROM SE MEXICO AND GUATEMALA TO THE GREATER ANTILLES. STRONG UPPER LEVEL SUBSIDENCE AND IMPLIED DRY AIR MASS IS NOTED WITHIN THE RIDGE AXIS. A VERY DRY AIR MASS IS OVER THE NE CARIBBEAN LIMITING THE SHOWER ACTIVITY. ATLANTIC OCEAN... A 1024 MB HIGH CENTERED NEAR 27N56W EXTENDS A RIDGE WWD ACROSS THE WESTERN ATLC AND FLORIDA INTO THE GULF OF MEXICO. A NEARLY STATIONARY 1008 MB LOW PRES SYSTEM IS OVER THE CENTRAL ATLC NEAR 24N43W. A TROUGH EXTENDS FROM THE LOW TO NEAR 14N47W. AT THIS POINT...A SHEAR LINE IS ANALYZED ON THE 18Z MAP ALONG 12N55W 12N62W 11N67W. A BAND OF LOW/MID CLOUDS IS ASSOCIATED WITH THE TROUGH AND SHEAR LINE. A STATIONARY FRONT ALSO EXTENDS FROM THE LOW TO THE N BEYOND 31N41W. A NARROW UPPER LEVEL TROUGH IS SUPPORTING THIS FEATURE. PRES GRADIENT BETWEEN THE LOW AND THE HIGH PRES IS PRODUCING AN AREA OF NLY WINDS IN THE 20 TO 30 KT RANGE N OF 20N BETWEEN THE STATIONARY FRONT AND 51W. THE REST OF THE TROPICAL N ATLANTIC TO THE EAST IS UNDER SURFACE RIDGING FROM A 1033 MB HIGH N OF THE AREA. A BROAD UPPER RIDGE COVERS THE TROPICAL ATLC S OF 20N AND BETWEEN THE W AFRICAN COAST AND 30W SUPPORTING DRY CONDITIONS. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ GR