000 AXNT20 KNHC 211738 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT MON MAR 21 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...ITCZ... ITCZ AXIS IS ANALYZED ALONG 5N5W 1N16W 2N25W 1N40W CROSSING 49W INTO SOUTH AMERICA. SCATTERED MODERATE/STRONG CONVECTION IS WITHIN 75/90 NM EITHER SIDE OF THE ITCZ BETWEEN 32W-39W. CLUSTERS OF SIMILAR CONVECTION ARE WITHIN 90 NM OF THE ITCZ E OF 23W TO INLAND OVER SW AFRICA. ...DISCUSSION... GULF OF MEXICO... BROAD UPPER RIDGE COVERS THE GULF OF MEXICO ANCHORED IN THE W BAY OF CAMPECHE WITH THE AXIS EXTENDING N OVER THE CENTRAL PLAIN STATES GIVING THE GULF NW TO N FLOW ALOFT. STRONG SUBSIDENCE AND DRY STABLE AIR ALOFT ALSO DOMINATES MUCH OF THE GULF WITH THE EXCEPTION OF ALONG THE COAST OF TEXAS WHERE UPPER LEVEL MOISTURE FROM THE E PACIFIC REGION IS BEING DRAWN ACROSS MEXICO AND TEXAS. DENSE MULTILAYERED CLOUDS WITH POSSIBLE ISOLATED SHOWERS ARE INLAND OVER TEXAS. ANOTHER EXCEPTION ARE SCATTERED SHOWERS IN THE THE STRAITS OF FLORIDA S OF 25N BETWEEN 81W-83W ASSOCIATED WITH THE DISSIPATING FRONTAL BOUNDARY THAT IS CURRENTLY ACROSS THE MIDDLE KEYS. A SURFACE RIDGE COVERS THE REMAINDER OF THE GULF ANCHORED OVER BY A 1029 MB HIGH OVER SOUTH CAROLINA AND A 10 31 MB HIGH IN THE NW ATLC GIVING THE REMAINDER OF THE GULF FAIR WEATHER THIS AFTERNOON. SURFACE RIDGE WILL REMAIN IN CONTROL OF THE GULF THROUGH TUE WITH THE PRESSURE GRADIENT RELAXING SOMEWHAT TUE NIGHT THROUGH THE END OF THE WEEK. CARIBBEAN SEA... THE UPPER RIDGE OVER THE GULF OF MEXICO COVERS THE NW CARIBBEAN GIVING THE AREA N TO NE WINDS ALOFT WITH STRONG SUBSIDENCE AND DRY STABLE AIR ALOFT W OF A LINE FROM HISPANIOLA TO NE NICARAGUA. A LARGE UPPER RIDGE ANCHORED OVER THE DEEP TROPICS COVERS THE REMAINDER OF THE CARIBBEAN GIVING THE AREA E OF THE ABOVE LINE SW TO W FLOW ALOFT. THE TIGHT PRESSURE GRADIENT OVER THE CARIBBEAN IS BEING GENERATED BY THE SURFACE RIDGE OVER THE GULF OF MEXICO AND THE W ATLC AND THE LOWER PRESSURE OVER THE TROPICS TO PRODUCE STRONG NE TRADE WINDS ACROSS THE BASIN WITH THE STRONGEST WINDS ALONG THE COAST OF COLOMBIA. LOW LEVEL MOISTURE REMAINS ACROSS THE CARIBBEAN GENERATING PATCHES OF SCATTERED SHOWERS USHERED IN ON THE TRADE WINDS MAINLY W OF LINE FROM E CUBA TO NW HONDURAS. THE SURFACE RIDGE OVER THE GULF OF MEXICO AND W ATLC WILL MAINTAIN STRONG NE TRADE WINDS ACROSS AREA THROUGH THU RELAXING SOME OVER THE N WATERS ON FRI. ATLANTIC OCEAN... A SURFACE RIDGE DOMINATES THE W ATLC INTO THE GULF OF MEXICO ANCHORED BY A 1031 MB HIGH ABOUT 300 NM NW OF BERMUDA AND A 1029 MB HIGH OVER SOUTH CAROLINA. BROAD UPPER TROUGH COVERS THE W ATLC N OF 22N W OF 45W SUPPORTING A WELL DEFINED COLD FRONT THAT ENTERS THE REGION NEAR 32N47W EXTENDING ALONG 23N60W TO THE BAHAMAS NEAR 24N76W WHERE IT BEGINS TO DISSIPATE TO OVER THE MIDDLE FLORIDA KEYS. SCATTERED SHOWERS ARE WITHIN 60 NM OF THE FRONT WITH COLD AIR STRATOCUMULUS CLOUDS N AND W OF THE FRONT OVER THE REMAINDER OF THE W ATLC. A WEAKENING 1008 MB LOW IS JUST TO THE E OF THE FRONT NEAR 28N47W WITH A SURFACE TROUGH THAT EXTENDS ALONG 22N45W TO 13N51W. A SHARP UPPER RIDGE IS TO THE E OF THIS SURFACE TROUGH ENHANCING SCATTERED SHOWERS WITHIN 250 NM E OF THE SURFACE TROUGH MAINLY N OF 20N. A WEAK SURFACE RIDGE DOMINATES THE E ATLC ANCHORED BY A 1020 MB HIGH E OF THE CANARY ISLANDS NEAR 27N27W LEAVING THE REMAINDER OF THE ATLC FAIR WEATHER THIS AFTERNOON. THE W ATLC COLD FRONT WILL DISSIPATE OVER THE CENTRAL ATLC THROUGH TUE. HIGH PRES WILL CONTINUE TO BUILD IN WAKE OF FRONT WITH A RIDGE EXTENDING ALONG THE N PORTION OF THE DISCUSSION AREA TUE SHIFTING SOUTHWARD ON THU. A SECOND COLD FRONT PASS THROUGH NE ATLC TUE NIGHT AND WED. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ PAW