000 AXPZ20 KNHC 160952 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC MON MAY 16 2011 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 AND OTHER TROPICAL CONVECTION... THE ITCZ AXIS IS ALONG 08N98W TO 05N127W TO 00N140W WITH AN EMBEDDED LOW PRESSURE AT 05N127W ESTIMATED AT 1012 MB. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS OBSERVED WITHIN 180 NM EITHER SIDE OF A LINE FROM 10N96W TO 04N120W...AND ALSO IN TWO SMALL CLUSTERS...WITHIN 15 NM OF 04N124W AND 05N128W. A MONSOON TROUGH IS ANALYZED FROM 15N93W TO 08N98W. ISOLATED MODERATE AND STRONG CONVECTION IS WEAKENING WITHIN 150 NM EITHER SIDE OF A LINE FROM 09N79W TO 04N95W. SCATTERED MODERATE TO STRONG CONVECTION HAS MOVED OFF THE COAST CENTRAL AMERICA WITHIN 30 NM OF 12.5N90W AND 14.5N93W...BUT IS WEAKENING IN BOTH INTENSITY AND COVERAGE AT THE MOMENT. ...DISCUSSION... AN UPPER LEVEL TROUGH DOMINATES THE WESTERN SEABOARD OF N AMERICA EXTENDING S INTO THE DISCUSSION AREA FROM 32N127W TO A BASE OVER THE DEEP TROPICS AT 10N138W. A BAND OF UPPER LEVEL MOISTURE PRECEDES THE TROUGH...WITHIN 150 NM EITHER SIDE OF A LINE FROM 20N130W TO BEYOND 32N112W AND ACROSS SOUTHERN ARIZONA. A NARROW BAND OF DRY AIR EXTENDS FROM SE CALIFORNIA TO NEAR 28N130W BUT WILL SOON BE REPLACED BY DENSE UPPER MOISTURE ROTATING E THROUGH THE UPPER TROUGH...CURRENTLY OBSERVED OVER THE AREA N OF A LINE FROM 30N140W TO 31N125W TO SE NEVADA. AN UPPER RIDGE CONTINUES TO EXTEND E ACROSS THE DEEP TROPICS S OF 09N TO THE W OF 130W. THE NORTHERLY UPPER FLOW SEEMS TO BE TAPPING DRY AIR ACCOMPANYING THE PREVIOUS DESCRIBED UPPER TROUGH TO THE N...AND IS SUPPRESSING CONVECTION ALONG THE ITCZ BETWEEN 132W AND 142W. AN UPPER ANTICYCLONE IS CENTERED NEAR 07N95W WITH AN UPPER RIDGE EXTENDING SW TO A SHARP CREST AT 06N126W...AND AN UPPER RIDGE ALSO EXTENDS NW TO BEYOND 31N108W AND AMPLIFYING NORTHWARD. AN UPPER CYCLONE HAS DEVELOPED S OF THE EQUATOR AT 02N118W. CONVECTION IS ENHANCED ALONG THE ITCZ BETWEEN 110W AND 130W WITH SOME OF THE DEBRIS MOISTURE PULLING S ACROSS THE EQUATOR BETWEEN 120W AND 130W IN RESPONSE TO THE UPPER CYCLONE. SOME OF THE DEBRIS MOISTURE IS ALSO ADVECTED N AROUND THE W PERIPHERY OF THE UPPER RIDGE...WITHIN 120 NM EITHER SIDE OF A LINE FROM 14N110W TO 22N112W...THEN TURNING NE ACROSS THE RIDGE AXIS OVER CENTRAL OLD MEXICO...EVENTUALLY EVAPORATING OVER THE UPPER LEVELS OF THE SW GULF OF MEXICO. SOME OF THIS MOISTURE SEEMS TO HAVE CONTRIBUTED TO A CLUSTER OF THUNDERSTORMS THAT DEVELOPED FOR THE SECOND NIGHT OVER SOUTHEASTERN OLD MEXICO... WITH THE REMNANTS NOW MOVING S TO ALONG THE COAST OF CENTRAL AMERICA AS PREVIOUSLY MENTIONED. DEBRIS MOISTURE IS NOTED OVER THE DEEP TROPICS S OF 10N E OF 110W WITH SOME SPREADING S ACROSS THE EQUATOR...BUT SOME OF THE MOISTURE ALSO SPREADS NE ACROSS THE CARIBBEAN IN RESPONSE TO A UPPER TROUGH OVER THE W CARIBBEAN. AT THE LOW LEVELS A BROAD SURFACE RIDGE EXTENDS ALONG 29N140W TO NEAR 17N110W. TIGHT PRESSURE GRADIENT WELL NE OF THE RIDGE IS MAINTAINING NW WINDS AT 15 TO 20 KT...WITH SEAS 6 TO 8 FT.... WITHIN ABOUT 150 NM W OF THE BAJA CALIFORNIA PENINSULA. NORTHERLY SWELLS...WITH SEAS HEIGHTS TO 11 FT...HAS SPREAD S TO ALONG 25N W OF 122W AND SHOULD CONTINUE S TO ALONG 20N TUE BEFORE BEGINNING TO SUBSIDE. NE TRADES TO THE SW OF THE RIDGE...IN THE AREA BOUNDED BY 07N TO 15N BETWEEN 133W AN 140W...HAVE DIMINISHED TO 15 TO 20 KT AND EXPECTED TO FURTHER DIMINISH ON TUE. CROSS EQUATORIAL SOUTHERLY SWELL WITH SEAS TO 9 FT IS NOTED S OF 04N BETWEEN 100W AND 137W. THESE SOUTHERLY SWELLS WILL SPREAD N TO OVER THE WATERS S OF LINE FROM 17N140W TO 17N115W TO 10N90W TONIGHT EVENTUALLY REACHING THE COAST OF CENTRAL AMERICA AND THE SOUTHERN BAJA CALIFORNIA PENINSULA TUE NIGHT WITH A PERIOD OF 18 TO 20 SECONDS. $$ NELSON