000 AXPZ20 KNHC 180948 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC WED MAY 18 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. ...MONSOON TROUGH AND ITCZ AND OTHER TROPICAL CONVECTION... A MONSOON TROUGH EXTENDS FROM CENTRAL AMERICA AT 15N96W TO THE ITCZ AXIS NEAR 06N123W WHICH CONTINUES W TO BEYOND 03N140W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS NOTED FROM 05N TO 08 BETWEEN 82W AND 88W AND WITHIN THE AREA FROM 04N TO 10N BETWEEN 91W AND 110W...BUT IS CURRENTLY DECREASING IN INTENSITY. SIMILAR CONVECTION IS NOTED N OF 11N BETWEEN 94W AND 101W. ...DISCUSSION... AN UPPER LEVEL TROUGH EXTENDS SW FROM SOUTHERN ARIZONA TO 30N120W TO 22N140W...AND THEN INTO AN UPPER CYCLONE NEAR 19N142W...WITH AN UPPER TROUGH EXTENDING SE FROM THE CYCLONE TO A BASE AT 06N138W. A BAND OF DRY UPPER AIR IS NOTED WITHIN 120 NM OF LINE FROM SE TEXAS TO ACROSS OLD MEXICO ALONG 27N...THEN ACROSS THE SOUTHERN BAJA CALIFORNIA PENINSULA TO 23N140W...AND THEN S OVER THE W SEMICIRCLE OF THE UPPER CYCLONE. A BAND OF UPPER MOISTURE HAS ROTATED AROUND THE E SEMICIRCLE OF THE CYCLONE...OVER THE AREA FROM 14N TO 20N W OF 120W. IMMEDIATELY TO NW OF THE BAND OF DRY UPPER AIR IS DENSE UPPER MOISTURE SHIFTING S INTO THE DISCUSSION AREA W OF 125W BUT SHIFTING SE OVER THE AREA E OF 125W TO AS FAR E AS WESTERN TEXAS. THE UPPER FLOW HAS BECOME SOUTHWESTERLY OVER THE DEEP TROPICS S OF 12N TO THE W OF 130W. CONVECTION FLARED EARLIER ALONG THE ITCZ BETWEEN 133W AND 145W...WITH THE DEBRIS MOISTURE NOW EVAPORATING IN THE SAME AREA AS THE UPPER LEVELS APPEAR DRY S OF 12N W OF 128W. AN UPPER ANTICYCLONE IS ESTIMATED NEAR 11N97W WITH AN UPPER RIDGE EXTENDING SW TO A SHARP CREST AT 08N126W...AND AN UPPER RIDGE EXTENDING E TO ANOTHER SHARP CREST OVER COLOMBIA AT 08N75W. AN UPPER RIDGE ALSO EXTENDS N TO A CREST NOW COLLAPSING OVER OLD MEXICO AT 27N107W. DEBRIS MOISTURE FROM PREVIOUS CONVECTION ALONG THE ITCZ BETWEEN 110W AND 128W IS ADVECTED NE AROUND THE UPPER RIDGE BETWEEN 115W AND 125W AND EVAPORATES NEAR 15N115W. DENSE DEBRIS MOISTURE IS OBSERVED UNDER THE UPPER RIDGE...FROM 04N TO 18N BETWEEN 80W AND 100W. AT THE LOW LEVELS A BROAD SURFACE RIDGE EXTENDS ALONG 27N140W TO NEAR 15N115W. THE RIDGE WILL CONTINUE TO BLOCK THE SOUTHERN ADVANCE OF COLD FRONTS TO OVER THE NORTHERN WATERS...BUT THE ASSOCIATED NORTHERLY SWELLS WILL CONTINUE TO PROPAGATE S OVER THE SUBTROPICAL WATERS E OF 130W MERGING WITH WIND GENERATED NW SWELL ALONG THE W COAST OF BAJA CALIFORNIA PENINSULA...WITH COMBINED SEAS HEIGHTS TO 10 FT OVER THE PACIFIC WATERS N OF 20N BETWEEN 130W AND 105W. SOME SWELL REFRACTION IS POSSIBLE INTO THE SOUTHERN GULF OF CALIFORNIA. SOUTHERLY SWELL HAS PROPAGATED OVER THE ENTIRE AREA W OF 105W. THE SOUTHERLY CROSS EQUATORIAL SWELL HAS MOVED OVER THE TROPICAL PACIFIC WATERS E OF 105W WITH RESULTANT SEAS 8 TO 12 FT...EXCEPT 4 TO 7 FT SEAS IN THE WATERS NE OF THE GALAPAGOS ISLANDS TO THE COAST OF CENTRAL AMERICA BETWEEN ROUGHLY 85W AND 88W. GULF OF CALIFORNIA...A COLD FRONT WILL SWEEP ACROSS THE NORTHERN WATERS TONIGHT ACCOMPANIED BY A 20 TO 25 KT SW TO NW WIND SHIFT. $$ NELSON