000 AXNT20 KNHC 210550 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 105 AM EST TUE MAR 21 2006 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN SECTIONS OF SOUTH AMERICA...AND THE ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS... RADAR...AND METEOROLOGICAL ANALYSIS. BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0500 UTC. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 7N10W 2N26W THEN SHIFTS S OF EQUATOR AT 36W TO S AMERICA AT 2S43W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED WITHIN 90 NM N AND WITHIN 120 NM S OF THE ITCZ E OF 22W THEN IS NOTED WITHIN 60 NM EITHER SIDE OF LINE 2N21W 3N344W. ...DISCUSSION... GULF OF MEXICO... AN UPPER RIDGE EXTENDS N FROM AN ANTICYCLONE OVER THE NW CARIBBEAN ALONG 83W. AN UPPER TROUGH IS SWINGING SE ACROSS CENTRAL TEXAS. SQUEEZED BETWEEN THE APPROACHING TROUGH AND THE RIDGE IS A MOISTURE PLUME ORIGINATING IN THE CENTRAL PACIFIC SEVERAL DAYS AGO. THE PLUME NOW CROSSES OLD MEXICO AND THE NW GULF OF MEXICO WITHIN 150 NM EITHER SIDE OF LINE 20N105W 27N93W...THEN NARROWS AND IS MOVES ACROSS THE FLORIDA PANHANDLE...MERGING WITH ADDITIONAL DEBRIS MOISTURE FROM ENHANCED TSTMS NEAR 33N85W. OTHERWISE...DRY UPPER AIR AND SUBSIDENCE IS INDICATED SE OF LINE 28N83W 20N97W. A SURFACE COLD FRONT EXTENDS FROM LOUISIANA TO NE OLD MEXICO AT 0300Z. MULTILAYERED CLOUDS AND SCATTERED SHOWERS ARE NOTED WITHIN 120 NM E OF THE FRONT. THE COLD FRONT WILL CONTINUE E TO A POSITION FROM TAMPA TO THE NW YUCATAN PENINSULA IN 24 HOURS ACCOMPANIED BY SLIGHTLY COOLER AND DRIER CONDITIONS BEHIND THE FRONT. CARIBBEAN... AN UPPER LEVEL ANTICYCLONE IS CENTERED NEAR 20N80W WITH ITS ENVELOPE OF ANTICYCLONIC FLOW DOMINATING THE THE NW CARIBBEAN. ANOTHER UPPER ANTICYCLONE IS CENTERED OVER VENEZUELA WITH A RIDGE EXTENDING NW AND N CRESTING GENTLY OVER THE CARIBBEAN ALONG 14N83W 15N72W 16N61W. A SMALL UPPER CYCLONE IS EMBEDDED NEAR 18N73W. UPPER DEBRIS MOISTURE IS SPREADING E ACROSS THE YUCATAN CHANNEL. A SMALL BAND OF UPPER MOISTURE IS NEAR 12N78W THAT ORIGINATED FROM CONVECTION OVER COSTA RICA MON AFTERNOON. A FEW STREAKS OF CIRRUS THAT FORMED FROM CONVECTION OVER NORTHERN COLOMBIA AND VENEZUELA IS OBSERVED OVER THE E CARIBBEAN. OTHERWISE DRY UPPER AIR AND SUBSIDENCE IS INDICATED ACROSS THE CARIBBEAN SEA. ATLANTIC... A MID-UPPER RIDGE IS SHIFTING E ACROSS THE DISCUSSION AREA W OF 75W. THE CENTRAL ATLANTIC IS DOMINATED BY A LONGWAVE TROUGH WITH THE MAIN CYCLONE OVER NEWFOUNDLAND. AN UPPER TROUGH EXTENDS INTO THE SUBTROPICAL ATLC WITH A MEAN AXIS ENTERING THE DISCUSSION AREA AT 31N50W AND CONTINUING S TO A BASE NEAR 22N57W. THE UPPER FLOW IS ONLY SLIGHTLY CYCLONIC BETWEEN 75W AND 40W. AT THE SURFACE...AN INITIAL COLD FRONT IS LOSING IDENTITY ALONG 31N40W 20N63W AND IS ACCOMPANIED BY SCATTERED TO BROKEN LOW LEVEL CLOUDS AND ISOLATED SHOWERS. A SECONDARY COLD FRONT LIES ALONG 31N44W TO 22N70W WITH LOCALLY BROKEN STRATOCUMULUS CLOUDS COVERING THE AREA NW OF THE FRONT. YET ANOTHER COLD SURGE IS ALONG 32N BETWEEN 64W AND 78W...BUT IS PARTIALLY BLOCKED BY A SURFACE HIGH PRES 1017 MB AT 28N72W. FARTHER EAST...A MID-UPPER LEVEL RIDGE EXTENDS ALONG 15N43W TO BEYOND 32N30W. AN UPPER LEVEL TROUGH EXTENDS SW INTO THE DISCUSSION AREA ALONG 32N9W TO A BASE AT 14N26W. AN UPPER ANTICYCLONE IS OVER AFRICA AT 13N11E WITH A RIDGE EXTENDING WSW TO NEAR 5N20W AND IS ENHANCING THE ITCZ E OF 20W. A BAND OF DRY UPPER AIR IS INDICATED WITHIN 210 NM EITHER SIDE OF LINE 20N50W 19N25W 23N10W. AT THE SURFACE...A 1022 MB HIGH IS LOCATED NEAR 28N30W. $$ NELSON