000 AXNT20 KNHC 201744 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 105 PM EST SUN FEB 20 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...ITCZ... THE INTERTROPICAL CONVERGENCE ZONE AXIS IS ANALYZED FROM THE COAST OF LIBERIA NEAR 05N09W TO 02N20W TO 03N33W AND CONTINUES SOUTH OF THE AREA AND EQUATOR TO THE COAST OF BRAZIL NEAR 03S42W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS WITHIN 120 NM N OF THE AXIS BETWEEN 34N AND 39W. ...DISCUSSION... GULF OF MEXICO... A BROAD UPPER RIDGE COVERS THE GULF WATERS WITH THE MAIN AXIS ALONG 92W. WATER VAPOR SATELLITE IMAGERY INDICATES VERY DRY AIR OVER THE GULF UNDER MODERATE TO STRONG SUBSIDENCE WITH MAINLY CLEAR SKIES ACROSS THE REGION THIS AFTERNOON. THE EXCEPTION IS IN THE N CENTRAL GULF S OF LOUISIANA WHERE DENSE SEA FOG IS OCCURRING DUE TO WARMER AIR MOVING OVER THE COOLER WATERS. THIS FOG IS REDUCING VISIBILITIES TO LESS THAN ONE MILE. AT THE SURFACE A RIDGE EXTENDS FROM NEAR APALACHEE BAY TO THE BAY OF CAMPECHE ANCHORED BY HIGH PRES LOCATED OVER THE U.S. GREAT LAKES REGION. THE RIDGE WILL BECOME ORIENTED ALONG 26N TO 27N TONIGHT INTO MON AS NEW HIGH PRES FORMS IN THE ATLANTIC E OF FLORIDA. A WEAK COLD FRONT WILL MOVE INTO THE NW GULF EARLY TUE MORNING BECOMING STATIONARY LATE TUE OVER THE N GULF WATERS THEN DISSIPATING WED AS RIDGING BUILDS SW FROM THE CAROLINAS. CARIBBEAN SEA... A MID TO UPPER LEVEL TROUGH EXTENDS FROM THE W CENTRAL ATLANTIC SW ACROSS THE E CARIBBEAN WITH LIMITED MID LEVEL MOISTURE OUT AHEAD OF THE AXIS. BROAD UPPER RIDGING EXTENDS FROM CENTRAL COLOMBIA NW TOWARD NICARAGUA WITH VERY DRY AIR IN PLACE UNDER THE RIDGE. SCATTERED SHOWERS ARE OCCURRING ACROSS THE BASIN AS COLDER AIR ALOFT MOVES OVER THE WARMER CARIBBEAN WATERS. WEAK SURFACE LOW PRES IS LOCATED ALONG THE NW COAST OF COLOMBIA RESULTING IN STRONGER TRADES NEAR THE COAST BETWEEN THE LOW AND SURFACE RIDGING N OF THE AREA. NEW ATLANTIC HIGH PRES FORMS N OF THE AREA MON THROUGH WED WHICH WILL INCREASE TRADES ACROSS THE CARIBBEAN. LARGE LONG PERIOD NW SWELL OF 10 TO 12 FEET WILL SEEP THROUGH THE E CARIBBEAN ATLANTIC PASSAGES LATE MON SUBSIDING BY LATE TUE. ATLANTIC OCEAN... AN UPPER TROUGH EXTENDS INTO THE AREA NEAR 32N57W TO 27N68W. A REINFORCING UPPER TROUGH EXTENDS FROM AN UPPER CYCLONIC CIRCULATION LOCATED WELL N OF THE AREA NE OF THE COAST OF NEWFOUNDLAND TO NEAR 31N66W. MID TO UPPER LEVEL MOISTURE LOCATED WITHIN 300 NM AHEAD OF THE FIRST TROUGH IS BEING ADVECTED FROM THE SW TO THE NE AHEAD OF THE TROUGH AXIS. AN ATTENDANT SURFACE COLD FRONT REACHES FROM NEAR 32N54W TO 26N70W WITH A REMNANT SHEAR AXIS EXTENDING FROM THERE TO NEAR GRAND BAHAMA. SCATTERED SHOWERS AREA OCCURRING WITHIN 60 NM AHEAD OF THE SURFACE FEATURES. THE SECOND TROUGH WILL USHER IN A REINFORCING SURFACE COLD FRONT TONIGHT THROUGH MON NIGHT WITH GALE FORCE WINDS DEVELOPING BOTH AHEAD OF AND BEHIND THIS REINFORCING FRONT BEGINNING AT 18 UTC THIS AFTERNOON DIMINISHING TO LESS THAN GALE FORCE BY 00 UTC MON AS THE REINFORCING FRONT WEAKENS. MEANWHILE ADDITIONAL SCATTERED SHOWERS ARE OCCURRING ALONG THE COASTS OF EASTERN CUBA EASTWARD TO THE VIRGIN ISLANDS BEING OROGRAPHICALLY ENHANCED AS THE N TO NE FLOW ENCOUNTERS THE LAND MASSES. BROAD UPPER RIDGING COVERS THE MAJORITY OF THE REMAINDER OF THE ATLANTIC W OF 30W. AN UPPER CYCLONIC CIRCULATION IS LOCATED NEAR 10N25W WITH A TROUGH EXTENDING S TO THE EQUATOR NEAR 20W. CONVECTION IS BEING ENHANCED ALONG THE ITCZ BETWEEN THIS UPPER RIDGE AND CYCLONE MAINLY BETWEEN 34W AND 39W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ LEWITSKY