AXNT20 KNHC 261736 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 105 PM EST WED MAR 26 2003 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...GULF OF MEXICO...CARIBBEAN SEA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE EQUATOR TO 32N INCLUDING NORTHERN SECTIONS OF SOUTH AMERICA. THE FOLLOWING INFORMATION IS BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL ANALYSIS. BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. SPECIAL FEATURES... NONE. TROPICAL WAVES/ITCZ... AXIS OF ITCZ-RELATED CLOUDS/CONVECTION IS CENTERED ALONG 1N1W 4N6W 1N16W 3N22W 1S47. SCATTERED MODERATE TO STRONG WITHIN 60 NM OF 1N7W. WIDELY SCATTERED MODERATE ISOLATED STRONG OBSERVED ELSEWHERE S OF 3N E OF 17W. MIDDLE/UPPER LEVEL SYNOPTIC FEATURES... AN ILL-DEFINED UPPER ANTICYCLONE IS CENTERED OVER THE E PACIFIC NEAR 11N87W WITH A RIDGE AXIS EXTENDING NE ACROSS CENTRAL AMERICA AND ACROSS FLORIDA TO A SHARP CREST AT 31N77W. AN UPPER MOISTURE PLUME ORIGINALLY FROM ITCZ CONVECTION OVER THE E PACIFIC IS CONCENTRATED OVER THE SE GULF OF MEXICO AND S FLORIDA AND IS ADVECTING RAPIDLY E. MODERATE TO STRONG SUBSIDENCE NOTED S OF 20N BETWEEN 80W AND 100W. A LONG WAVE TROUGH OVER THE EASTERN CONUS HAS MEAN AXIS N OF 28N ALONG 80W. AN EMBEDDED STRONG SHORT WAVE HAS DUG S TO 25N ALONG 90W. A SECOND SHORTWAVE TROUGH IS LOCATED OVER THE ATLC N OF 26N ALONG 63W. THE WESTERN SHORTWAVE HAS A DEEP LAYERED CYCLONE AT 29N87W WITH A SURFACE REFLECTION 1012 MB AT 30N95W. AN UPPER TROUGH EXTENDS SW ALONG 23N94W TO 22N106W AND WELL DEPICTED ON WATER VAPOR IMAGERY WITH STRONG UPPER SUBSIDENCE W OF TROUGH. UPPER DIFFLUENCE E SEMICIRCLE IS SUPPORTING CONVECTION ALONG A SQUALL LINE CURRENTLY N OF 24.5N ALONG 93W. THE EASTERN SHORTWAVE HAS HAS A LARGE CYCLONE NEAR 34N59W WITH THE ASSOCIATED CYCLONIC FLOW DOMINATING THE REGION N OF 26N BETWEEN 70W AND 50W WITH STRONG SUBSIDENCE OBSERVED. A TROUGH EXTENDS SW ACROSS HISPANIOLA TO A SMALL CYCLONE AT 10N77W. ASSOCIATED UPPER LEVEL SUBSIDENCE OBSERVED S OF 22N BETWEEN 80W AND 50W. THE E ATLC IS DOMINATED BY A LARGE UPPER ANTICYCLONE CENTERED NEAR 3N37W WITH LARGE UPPER LEVEL RIDGE CREST EXTENDING N OF AREA ALONG ROUGHLY 28N54W 31N37W 32N15W. AN EMBEDDED UPPER CYCLONE HAS CUT OFF WITHIN THE THE ANTICYCLONIC FLOW AND IS CENTERED NEAR 17N44W. UPPER DIFFLUENCE IS ENHANCING CONVECTION ALONG A SURFACE FRONT WITH THE RESULTANT UPPER MOISTURE PLUME NOTED WITHIN 120 NM EITHER SIDE OF LINE 26N58W TO 36N40W. S OF THIS MOISTURE STRONG UPPER SUBSIDENCE NOTED N OF 8N BETWEEN 50W AND 40W. SURFACE SYNOPTIC FEATURES... 1018 MB HIGH PRES CENTERED NEAR 32N75W WILL SHIFT NE OF AREA TONIGHT. A STATIONARY 1019 MB HIGH PRES IS AT 25N36W WITH RIDGE E TO 22N20W AND RIDGE W TO 21N56W. A 1014 MB LOW PRES IS CENTERED NEAR 32N94W WITH A COLD FRONT S ALONG 27N95W TO 25N102W. A 1006 MB LOW PRES IS CENTERED NEAR 33N54W WITH A COLD FRONT SW ALONG 26N60W TO 19N71W THEN DIFFUSE TO 18N86W. A COLD FRONT IS BECOMING DIFFUSE ALONG 31N15W 26N25W. SIGNIFICANT CLOUDS/CONVECTION... GULF OF MEXICO... BROKEN TO OVERCAST MULTILAYERED CLOUDS WRAP AROUND THE NE SEMICIRCLE OF THE LOW PRES AND ARE ALSO OBSERVED WITHIN 120 NM E OF THE COLD FRONT. A BAND OF SHOWERS AND TSTMS WERE ANALYZED AS A PRE-FRONTAL SQUALL LINE AT 1200 UTC AND ARE STILL ORGANIZED OVER THE WATERS N OF 24N BETWEEN 92W AND 90W...MOVING E AT 15 KT. WIDELY SCATTERED LOW CLOUDS ARE NOTED OVER THE REMAINDER OF THE GULF WITH THIN BROKEN CIRRIFORM CLOUDS STREAMING NE. SKIES ARE CLEARING OVER THE SW SEMICIRCLE OF THE LOW. CARIBBEAN SEA... ONLY A FEW TOWERING CUMULUS ARE STILL OBSERVED DENOTING AN APPROXIMATE POSITION OF THE DISSIPATING FRONTAL TROUGH OR SHEAR AXIS THAT EXTENDS FROM HISPANIOLA TO THE NE YUCATAN PENINSULA. CONVECTION HAS BECOME SCATTERED OVER HISPANIOLA ASSOCIATED WITH THE COLD FRONT. WIDELY SCATTERED SHOWERS AND A FEW TSTMS ARE ALSO NOTED N OF 14N E OF 70W MORE HEAVILY CONCENTRATED AT 18N64W. TROPICAL ATLANTIC... EXCEPT FOR THE ITCZ...LOCALLY BROKEN LOW AND MID LEVEL CLOUDS WITH WIDELY SCATTERED SHOWERS AND A FEW TSTMS NOTED WITHIN 240 NM OF OF THE UPPER LEVEL CYCLONE AT 17N44W. SUBTROPICAL ATLANTIC... OVERCAST MULTILAYERED CLOUDS WITH EMBEDDED TOWERING CUMULUS AND A FEW TSTMS ARE WITHIN 90 NM OF THE COLD FRONT ALONG 31N51W 20N70W. WIDELY SCATTERED STRATOCUMULUS NOTED ELSEWHERE W OF 60W WITH THIN BROKEN CIRRUS STREAMING NE OVER THE WATERS W OF 67W. $$ NELSON