000 AXPZ20 KNHC 190948 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC MON APR 19 2010 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0945 UTC. ...ITCZ... THE ITCZ AXIS EXTENDS FROM 08N77W TO 05N118W TO 09N130W TO 04N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED WITHIN ABOUT 150 NM EITHER SIDE OF A LINE FROM 08N102W TO 01N120W. ISOLATED MODERATE CONVECTION IS ALSO OBSERVED NEAR 05N88W...S OF 02N BETWEEN 98W AND 101W...AND NEAR 04N138W. ...DISCUSSION... A DEEP LAYERED CYCLONE NEAR 30N125W IS MOVING NW WHILE TRAILING A TROUGH SW TO 20N140W. A SECOND UPPER TROUGH HAS SWUNG SE TO A POSITION FROM 32N132W TO 29N140W. DENSE UPPER MOISTURE IS NOTED OVER THE AREA N OF 27N BETWEEN 117W AND 124W AND IS ADVECTED NE ACROSS SOUTHERN CALIFORNIA. OTHERWISE...DRY UPPER AIR IS NOTED N OF 20N W OF 120W. AN UPPER LEVEL ANTICYCLONE IS CENTERED NEAR 08N117W WITH AN UPPER RIDGE EXTENDING SW TO A SHARP CREST AT 03N135W...AN UPPER RIDGE EXTENDING E TO 10N102W...AND A SHORTWAVE UPPER RIDGE EXTENDING NE TO A CREST AT 32N106W. THIS SHORTWAVE RIDGE IS BECOMING EMBEDDED IN A LONGWAVE RIDGE NOW DOMINATING THE WESTERN SEABOARD OF N AMERICA. ITCZ CONVECTION IS ENHANCED BETWEEN 102W AND 123W...WITH SOME OF THE DEBRIS MOISTURE SPREADING S ACROSS THE EQUATOR NEAR 120W...AND SOME OF THE MOISTURE ADVECTED NW ALONG THE WESTERN RIDGE TO NEAR 16N123W...WHERE IT MERGES WITH A MORE PRONOUNCED TROPICAL PLUME THAT ORIGINATES OVER THE DEEP TROPICAL CENTRAL PACIFIC. THE COMBINED PLUME STRETCHES ACROSS THE DISCUSSION AREA ALONG THE PERIPHERY OF THE LARGE UPPER RIDGE...ROUGHLY WITHIN 240 NM EITHER SIDE OF LINE FROM 15N140W TO 22N116W WHERE THE MOISTURE FANS OUT ACROSS THE RIDGE CREST OVER THE AREA N OF 20N BETWEEN 117W AND 105W. THE MOISTURE PLUME BECOMES LESS DENSE AS IT CROSSES NORTHERN OLD MEXICO N OF 23N INTO AN UPPER TROUGH DESCRIBED NEXT. AN UPPER TROUGH EXTENDS S OVER THE CENTRAL GULF OF MEXICO ALONG 30N90W TO THE E PACIFIC AT 15N92W TO THE EQUATOR AT 99W WHERE THE UPPER DIFFLUENCE HAS ENHANCED CONVECTION FROM 02N TO 05S ALONG 98W. A BROAD UPPER RIDGE EXTENDS NW FROM S AMERICA ACROSS THE SW CARIBBEAN. DRY UPPER AIR IS INDICATED UNDER THE TROPICAL PACIFIC UPPER RIDGE...ROUGHLY FROM 08N TO 17N BETWEEN 116W AND 86W...MERGING WITH DRY UPPER AIR ADVECTED SE TO THE W OF THE GULF OF MEXICO UPPER TROUGH AXIS. DIFFLUENCE E OF THE GULF UPPER TROUGH AXIS IS ENHANCING CONVECTION OVER CENTRAL AMERICA BETWEEN 89W AND 83W. CONVECTION WAS ALSO ENHANCED EARLIER NEAR 06N86W. THE RESULTANT DEBRIS MOISTURE FROM THESE CONVECTIVE AREAS IS SPREADING NE ACROSS THE CARIBBEAN AND THE BAHAMAS. AT THE SURFACE...HIGH PRES OF 1014 MB IS MEANDERING NEAR 23N118W AND IS LOSING IDENTITY. LOW PRES NEAR 30N126W IS LIFTING NE WITH A COUPLE OF ITS FRONTAL TROUGHS QUICKLY LOSING THEIR BAROCLINICITY AS THEY BECOME ORIENTATED N TO S AND GRADUALLY DISSIPATE ALONG 120W OVER THE NEXT DAY OR SO. SCATTERED MODERATE TO STRONG CONVECTION IS OBSERVED WITHIN 180 NM 28N118W AND CONFIRMED BY LIGHTNING DATA. HIGH PRESSURE WILL BUILD FROM THE NW AS THESE FRONTAL TROUGHS WASH OUT DRIVING A NEW SERIES OF NW SWELL ACROSS THE NW WATERS STARTING TONIGHT. NE TRADES ALSO EXPECTED TO INCREASE AGAIN TO 20 KT OVER THE TROPICS W OF 130W. $$ NELSON