000 AXPZ20 KNHC 150954 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC SUN MAY 15 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 TROPICAL CONVECTION... THE ITCZ AXIS IS FLUCTUATING FROM 04N TO 05N BETWEEN 110W AND 140W. CONVECTION IS LIMITED TO ISOLATED MODERATE TO STRONG FLARE UPS WITHIN 120 NM EITHER SIDE OF A LINE FROM 07N104W TO 06N118W TO 04N123W. A MONSOON TROUGH IS ANALYZED FROM 08N82W TO 05N90W TO 06N108W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS OBSERVED WITHIN 180 NM EITHER SIDE OF A LINE FROM 07N78W TO 05N92W TO 08N103W. THE GRADIENT S OF THIS TROUGH AXIS HAS INCREASED SUPPORTING SOUTHERLY WINDS AT 15 TO 20 KT IN THE AREA S OF 05N BETWEEN 83W AND 90W...WITH SEAS 4 TO 7 FT. THESE SOUTHERLY WINDS ARE EXPECTED TO CONTINUE WITH SEAS BUILDING TO 8 FT TONIGHT THROUGH MON NIGHT. CONVECTION IS MOVING OFFSHORE THE COAST CENTRAL AMERICA FROM 91W TO 98W...WITH SCATTERED MODERATE ISOLATED STRONG CONVECTION NOTED CURRENTLY WITHIN 90 NM OF THE COAST WITH NEW CLUSTERS DEVELOPING WIHIN 15 NM OF A LINE FROM 14.5N98.5W TO 12.5N100.5W TO 08N101W. ...DISCUSSION... AN UPPER LEVEL TROUGH DOMINATES THE WESTERN SEABOARD OF N AMERICA WITH A DEEP LAYERED CYCLONE NEAR 44N129W WITH A MID TO UPPER TROUGH EXTENDING S OVER THE DISCUSSION AREA ALONG 32N125W TO A BASE OVER THE TROPICS AT 14N131W. UPPER LEVEL MOISTURE PRECEDING THE TROUGH HAS SHIFTED E OVER NORTHERN NEW MEXICO AND ARIZONA. ADDITIONAL UPPER MOISTURE W OF THE UPPER TROUGH AXIS SHOULD ROTATE E OVER NORTHERN CALIFORNIA LATER TODAY. OTHERWISE...DRY UPPER AIR IS SWINGING E ACROSS THE SUBTROPICS...ACROSS THE BAJA CALIFORNIA PENINSULA AND OVER OLD MEXICO TO THE N OF 27N. AN UPPER RIDGE EXTENDS E ACROSS THE DEEP TROPICS S OF 12N TO THE W OF 128W. THE ASSOCIATED UPPER DIFFLUENCE IS ENHANCING ITCZ CONVECTION WITH SOME OF THE DEBRIS MOISTURE SPREADING S ACROSS THE EQUATOR BETWEEN 130W AND 140W. SOME OF THE MOISTURE IS NOW SPREADING N AS WELL...MERGING WITH A TROPICAL PLUME THAT ORIGINATES IN THE CENTRAL PACIFIC...WITH THE COMBINED MOISTURE NOTED OVER THE AREA FROM 08N TO 22N W OF 128W. AN UPPER ANTICYCLONE IS QUASI STATIONARY NEAR 16N92W WITH AN UPPER RIDGE EXTENDING SW TO A SHARP CREST AT 10N116W...AND AN UPPER RIDGE ALSO EXTENDS E TO AN ILL DEFINED CREST NEAR 10N90W. AN UPPER RIDGE ALSO EXTENDS N TO CREST NEAR 31N105W WHICH APPEARS TO BE COLLAPSING S WITH TIME AS THE PREVIOUSLY DESCRIBED UPPER TROUGH APPROACHES FROM THE NW. DEBRIS MOISTURE FROM ITCZ CONVECTION BETWEEN 110W AND 122W IS ADVECTED N AROUND THE W PERIPHERY OF THE UPPER RIDGE...WITHIN 120 NM EITHER SIDE OF A LINE FROM 12N116W TO 21N111W...THEN TURNING NE ACROSS THE RIDGE AXIS OVER CENTRAL OLD MEXICO...EVENTUALLY EVAPORATING OVER THE UPPER LEVELS OF THE WESTERN GULF OF MEXICO. SOME OF THIS MOISTURE MAY HAVE CONTRIBUTED TO A LARGE CLUSTER OF INTENSE THUNDERSTORMS THAT DEVELOPED LAST NIGHT OVER SOUTHEASTERN OLD MEXICO...WITH THE REMNANTS NOW MOVING OFF THE COAST AS PREVIOUSLY MENTIONED. A LARGE AREA OF ITCZ DEBRIS MOISTURE IS NOTED OVER THE DEEP TROPICS FROM 02N TO 11N E OF 120W...BUT MOST OF THE MOISTURE EVAPORATES ALONG 12N AS THE UPPER LEVELS ARE DRY UNDER THE RIDGE...ROUGHLY WITHIN 120 NM EITHER SIDE OF A LINE FROM 12N92W TO 17N108W. AT THE LOW LEVELS A BROAD SURFACE RIDGE EXTENDS ALONG 29N140W TO 14N110W. TIGHT PRESSURE GRADIENT WELL NE OF THE RIDGE IS MAINTAINING NW WINDS AT 15 TO 20 KT...WITH SEAS 7 TO 9 FT.... WITHIN ABOUT 300 NM W AND SW OF THE BAJA CALIFORNIA PENINSULA. A COLD FRONT PASSING E ACROSS THE WATERS N OF 29N IS ACCOMPANIED BY NORTHERLY 15 TO 20 KT WINDS AND SEAS TO 10 FT IN NW SWELL. THE NORTHERLY WINDS ARE EXPECTED TO DIMINISH TO LESS THAN 20 KT TODAY...BUT THE NW AND N SWELL WILL DRIVE COMBINED SEA HEIGHTS TO 8 FT OVER THE WATERS N OF 25N W OF 122W TONIGHT...AND N OF 23N W OF 120W MON NIGHT. NE TRADES TO THE SW OF THE RIDGE ARE EXPECTED TO DIMINISH TO 15 KT BY TONIGHT. CROSS EQUATORIAL SWELL WITH SEAS TO 11 FT WILL MOVE INTO THE DEEP TROPICAL WATERS S OF 03N BETWEEN 110W AND 135W TONIGHT... SPREADING N TO OVER THE WATERS S OF LINE FROM 14N140W TO 14N120W TO 00N90W ON MON NIGHT. THESE SOUTHERLY SWELLS WILL ARRIVE AT THE COAST OF CENTRAL AMERICA AND THE SOUTHERN BAJA CALIFORNIA PENINSULA TUE NIGHT. $$ NELSON