000 AXPZ20 KNHC 012221 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 2205 UTC THU MAY 01 2008 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2200 UTC. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 07N78W TO 09N86W TO 08N95W TO 10N110W TO 08N117W TO 08N127W TO 03N140W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 180 NM S OF THE AXIS BETWEEN 83W-89W. SCATTERED MODERATE CONVECTION IS WITHIN 180 NM N OF THE AXIS BETWEEN 120W-128W...WITHIN 30 NM OF THE AXIS BETWEEN 90W-93W AND ALSO BETWEEN 110W-116W. ...DISCUSSION... E OF 100W... MID/UPPER RIDGE COVERS JUST ABOUT THE ENTIRE AREA N OF 07N INCLUDING CENTRAL AMERICA AND THE FAR WESTERN CARIBBEAN SEA. THE RIDGE IS FORECAST TO CHANGE LITTLE OVER THE NEXT 72 HRS. AS A RESULT...THE FLOW PATTERN WILL CONTINUE TO BE ZONAL N OF 14N WITH MODERATE SUBSIDENCE AND ASSOCIATED DRY AIR WITHIN THIS AREA AS SEEN IN SATELLITE WATER VAPOR IMAGERY. ANTICYCLONIC FLOW DUE TO THE RIDGE WILL CONTINUE TO TRANSPORT AMPLE UPPER LEVEL DEBRIS CLOUDINESS FROM THE FAR E PAC CONVECTION ALONG AND NEAR THE ITCZ LOCATED FROM 04N-09N BETWEEN 82W-89W. OVER THE SW 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 HERE. 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. THIS MAY ALLOW FOR CONVECTION TO REMAIN RATHER ACTIVE OVER THE FAR ERN PACIFIC THROUGH AT LEAST THE MIDDLE OF NEXT WEEK ESPECIALLY IF RIDGING IN THE UPPER LEVELS CHANGES LITTLE AS GFS MODEL PORTRAYS. W OF 100W... A RATHER SHARP MID/UPPER LEVEL TROUGH EXTENDS FROM NRN BAJA CALIFORNIA SW TO 28N122W TO 27N130W THEN BECOMES A SHEAR AXIS TO 25N136W TO 21N140W. NW UPPER LEVEL FLOW IS CHANNELING SEWD INTO THE BACK SIDE OF THE TROUGH ALLOWING FOR FLOW PATTERN TO BE CONFLUENT THERE AND CREATING MODERATE SUBSIDENCE WITH ASSOCIATED DRY SINKING AIR NW OF A LINE FROM 29N115W TO 26N126W TO 22N140W. THE TROUGH IS FORECAST TO PUSH INLAND THE WESTERN UNITED STATES OVER THE NEXT FEW DAYS AS ANOTHER TROUGH SWINGS SEWD INTO SRN CALIFORNIA WITH AN EVENTUAL CUT-OFF LOW FORMING THERE...THEN LIFTING NEWD ACROSS THE SW UNITED STATES TUE AND WED IN ADVANCE OF UPPER LEVEL RIDGING THAT BUILDS EWD ACROSS THE NRN PORTION OF THE AREA. GFS SHOWS ANOTHER CUT-OFF LOW MOVING INTO THE FAR WRN PART OF THE AREA SUN AND MON...AND ALSO LIFTING NEWD AND BECOMING ABSORBED INTO A BROAD LONGWAVE TROUGH ON WED BEHIND THE FIRST LOW THAT MOVES ACROSS THE SW UNITED STATES. AT THE SURFACE...A STATIONARY 1026 MB HIGH CENTER N OF THE AREA NEAR 36N138W...EXTENDS A RIDGE SEWD THROUGH 27N128W TO 23N121W TO 16N108W. 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 OBSERVED THERE...AND THAT ARE FUNNELING SE ALONG THE NRN BAJA COAST AS FAR S AS 25N WITH 20 KT WINDS BETWEEN 118W-124W. THESE WINDS ARE FORECAST TO DIMINISH GRADUALLY OVER THE NEXT 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 MAY BE A REFLECTION OF A MID/UPPER TROUGH THAT EXTENDS FROM 20N140W SE TO 15N130W TO 10N124W TO NEAR 02N105W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION ASSOCIATED WITH THE TROUGH IS WITHIN 30 NM OF 10N128W. UPPER LEVEL DIVERGENCE TO THE E OF THE TROUGH SHOULD KEEP ITCZ CONVECTION RATHER ACTIVE BETWEEN 110W-125W THROUGH THE NEXT 36-48 HRS. TRADE WINDS FROM 10N-24N W OF OF 124W ARE EXPECTED TO DIMINISH THROUGH THE NEXT 72 HRS AS HIGH PRES CENTERED N OF THE AREA SHIFTS SLIGHTLY NEWD. $$ AGUIRRE