000 AXPZ20 KNHC 020343 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC FRI MAY 02 2008 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0315 UTC. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 08N83W TO 08N92W TO 10N104W TO 08N118W TO 08N127W TO 03N140W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 04N TO 07N BETWEEN 84W AND 88W. SCATTERED MODERATE CONVECTION IS WITHIN 120 NM N OF THE AXIS BETWEEN 123W-128W. ...DISCUSSION... E OF 125W... MID/UPPER RIDGE COVERS JUST ABOUT THE ENTIRE AREA N OF 09N INCLUDING CENTRAL AMERICA...MUCH OF MEXICO AND THE FAR WESTERN CARIBBEAN SEA. THE RIDGE IS FORECAST TO CHANGE LITTLE OVER THE NEXT 72 HRS...THEN SLOWLY MIGRATE EWD AS AN UPPER LEVEL TROUGH AND SUBSEQUENT UPPER LOW DEEPEN JUST W OF THE AREA. LATEST SATELLITE WATER VAPOR IMAGERY SHOWS A RATHER ZONAL FLOW PATTERN N OF 21N WITH MODERATE SUBSIDENCE AND ASSOCIATED DRY AIR N OF 25N WHERE THE UPPER FLOW BETWEEN THE RIDGE AND DEEP TROUGHING OVER THE GREAT PLAINS IS CONFLUENT. THE ANTICYCLONIC FLOW DUE TO THE RIDGE CONTINUES TO ADVECT AMPLE UPPER MOISTURE AND DEBRIS CLOUDINESS FROM DEEP TROPICAL PACIFIC CONVECTION ALONG AND NEAR THE ITCZ BETWEEN 115W-125W NEWD TOWARDS CENTRAL MEXICO AND INTO THE WRN GULF OF MEXICO. THE SE PORTION OF THE MID/UPPER LEVEL TROUGH W OF 125W EXTENDS SEWD THROUGH 09N118W TO NEAR 04N107W. OVER THE SE PORTION OF THIS AREA...MODERATE SUBSIDENCE IS NOTED WITH VERY LIMITED CONVECTION. SOME INCREASE IN UPPER LEVEL MOISTURE...FROM THE CONVECTION STATED ABOVE...IS NOTED S OF 06N BETWEEN 85W-89W. ONLY ISOLATED SHOWERS ARE NOTED THERE. NWP MODELS ARE IN FAIR AGREEMENT THAT LOW PRES WILL LINGER IN THE VICINITY OF THE ITCZ OVER THE FAR E PORTION OF THE AREA ALONG AND NEAR THE ITCZ ALLOWING CONVECTION TO REMAIN RATHER ACTIVE OVER THIS PORTION OF ERN PACIFIC THROUGH AT LEAST THE MIDDLE OF NEXT WEEK...ESPECIALLY SINCE IT WILL BE UNDER UPPER LEVEL RIDGING AS MENTIONED ABOVE. W OF 125W... AN UPPER LEVEL TROUGH EXTENDS FROM 32N128W SW TO 26N131W TO 21N137W. BEHIND THE TROUGH SATELLITE-DERIVED WINDS SHOW STRONG NW FLOW. WATER VAPOR IMAGERY REVEALS MODERATE TO STRONG SUBSIDENCE N OF 22N E OF THE TROUGH. THE TROUGH IS FORECAST TO MOVE E OF THIS AREA SUN NIGHT AND MON AS AN UPPER LEVEL LOW MENTIONED ABOVE EVOLVES OVER THE WRN PART AND DEEPENS AS IT TRACKS E AND THEN NNE BY THE MIDDLE OF NEXT WEEK. MID/UPPER LEVEL RIDGING BUILDS IN BEHIND THE LOW. ANOTHER TROUGH EXTENDS FROM NEAR 20N135W SE TO 10N125W AND FURTHER SE OF THE AREA. MID/UPPER LEVEL RIDGING BUILDS IN BEHIND THE LOW. BROAD MID/UPPER LEVEL ANTICYCLONIC FLOW COVERS THE AREA S OF THE TROUGH WITH UPPER LEVEL MOISTURE ENTERING THE FAR SW PORTION. AT THE SURFACE...A 1033 MB HIGH CENTER N OF THE AREA NEAR 35N135W...EXTENDS A RIDGE SEWD THROUGH 27N128W TO 22N118W. HIGH PRES COVERS THE AREA N OF 15N AND W OF 108W. THE RIDGING...IN COMBINATION WITH LOW PRES OVER THE WRN UNITED STATES...IS CREATING A TIGHT PRES GRADIENT ALONG THE CALIFORNIA WITH STRONG NORTHERLY WINDS AND LARGE SEAS OBSERVED THERE. THIS GRADIENT CONTINUES TO CHANNEL NW-N 20 KT WINDS SEWD ALONG THE NRN BAJA COAST AS FAR S AS 25N. THESE WINDS ARE FORECAST TO DIMINISH GRADUALLY OVER THE NEXT 48-72 HRS AS LOW PRES OVER THE WRN UNITED STATES MOVES E TO THE MIDWEST AND THE RIDGE WEAKENS SLIGHTLY. A SURFACE TROUGH MOVING W 10-15 KT IS ALONG 127W FROM 06N-10N. THIS TROUGH...BEING SUPPORTED BY THE MID/UPPER TROUGH STATED ABOVE...IS ENHANCING CONVECTION N OF THE ITCZ BETWEEN 123W-128W. UPPER LEVEL DIVERGENCE TO THE E OF THE TROUGH SHOULD KEEP ITCZ CONVECTION RATHER ACTIVE E OF 125W BETWEEN 117W-125W THROUGH THE NEXT 36-48 HRS. TRADE WINDS FROM 10N-25N W OF OF 123W ARE EXPECTED TO DIMINISH IN AREAL COVERAGE THROUGH THE NEXT 36-48 HRS AS HIGH PRES CENTERED N OF THE AREA SHIFTS SW AND WEAKENS WHILE LOW PRES OVER THE WRN UNITED STATES ALSO WEAKENS. $$ AGUIRRE