000 AXPZ20 KNHC 040356 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC FRI APR 04 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 2N79W 2N94W 3N110W 6N124W 6.5N140W. SCATTERED MODERATE CONVECTION IS WITHIN 180 NM S OF THE AXIS BETWEEN 92W-96W. ...DISCUSSION... A MID/UPPER LEVEL TROUGH HAS MOVED WELL INLAND THE SW UNITED STATES AS OBSERVED ON WATER VAPOR IMAGERY. IN ITS WAKE...NWLY FLOW IS RESULTING IN 20 KT NW-N WINDS WITH SEAS TO 8 FT IN THE FAR NE PART OF THE AREA. A SMALL POCKET OF MODERATE SUBSIDENCE AND DRY AIR LEFT BEHIND IN THE WAKE OF TROUGH IS BECOMING MOIST DUE TO A BATCH OF MID/UPPER LEVEL MOISTURE...ATTRIBUTED TO A RATHER LARGE UPPER LEVEL DIFFLUENT PATTERN PRESENT N OF 20N BETWEEN 121W-135W. A MID/UPPER LEVEL RIDGE AXIS EXTENDS FROM 22N124W NW TO 26N127W TO NW OF THE AREA AT 32N131W...WHICH IS RAPIDLY SPREADING EWD TOWARDS SRN CALIFORNIA AND NRN BAJA CALIFORNIA. THE RIDGE HAS PRACTICALLY FORMED DUE TO THE AMPLIFICATION OF A RATHER BROAD TROUGH THAT IS W OF THE REGION ALONG 148W. THE TROUGH IS PART OF AN ELONGATED CYCLONIC VORTEX MOVING SSW ABOUT 10 KT W OF THE AREA NEAR 30N148W...WITH AN OCCLUDED FRONT FROM THE LOW TO 34W144W...THEN A COLD FRONT S THROUGH 29N142W TO 22N149W. GALE FORCE WINDS ARE N OF THE AREA TO THE NE OF THE FRONT. BROKEN LOW AND MID LEVEL CLOUDS WITH WIDELY SCATTERED SHOWERS ARE WITHIN 75 NM EITHER SIDE OF THE FRONT. THE TYPICAL TRADE WIND BELT ZONE HAS DIMINISHED IN COVERAGE AS RIDGING INTO THE AREA HAS WEAKENED AHEAD OF THE FRONTAL SYSTEM. EVEN SEAS THERE HAVE LOWERED TO 6-7 FT IN LONG-PERIOD NW SWELL. S-SE SRN HEMISPHERIC LONG PERIOD SWELLS...UP TO 8 FT...ARE ARE POSSIBLE OVER THE FAR SRN WATERS NEAR THE EQUATOR BUT SHOULD FADE AWAY BEFORE REACHING MUCH FURTHER N INTO THE AREA. THE UPPER LEVEL CYCLONIC VORTEX IS FORECAST TO DROP THROUGH THE NEXT 48 HRS...THEN LIFT NE TOWARDS THE FAR NW CORNER OF THE AREA BY SUN...WHILE THE COLD FRONT STALLS JUST W OF THE AREA. EXPECT WINDS TO INCREASE OVER THE NW PART BEGINNING LATE FRI INTO SAT AS HIGH PRES N OF THE AREA BUILDS S CAUSING A SQUEEZE PLAY WITH LOW PRES ASSOCIATED WITH THE FRONT TIGHTENING THE PRES GRADIENT THERE WITH SE WINDS FORECAST TO INCREASE TO 20-25 KT...AND CONTINUE THROUGH EARLY NEXT WEEK BEFORE DIMINISHING TO 15-20 KT AS A RIDGE THEN BUILDS SE THROUGH 32N133W 20N117W. NW FLOW ALONG AND JUST W OF THE BAJA CALIFORNIA COAST IS EXPECTED TO CONTINUE OVER THE NEXT FEW DAYS AS THE PRES DIFFERENCE BETWEEN LOW PRES OVER THE SW UNITED STATED AND THE RIDGE ALLOW SUSTAIN A GRADIENT ADEQUATE TO SUPPORT THESE WINDS. MID/UPPER-LEVEL ANTICYCLONE CENTERED JUST SW OF MEXICO CONTINUES TO DOMINATE THE AREA S OF ABOUT 20N AND E OF 120W TO CENTRAL AMERICA WITH A MEAN RIDGE AXIS FROM 18N104W SW TO 14N111W TO 12N121W. WATER VAPOR IMAGERY CONTINUES TO INDICATE STRONG SUBSIDENCE UNDERNEATH THE RIDGE ACROSS THIS AREA...INHIBITING NOT ONLY ANY CONVECTION BUT NEARLY ALL CLOUD COVER. ONLY ISOLATED SHOWERS AND TSTMS ARE NOTED FROM 6N-13N BETWEEN 89W-98W. UPPER LEVEL MOISTURE IS EVIDENT TO THE NW AND N OF THE RIDGE WHERE IT IS CHANNELING IN TRAJECTORY TOWARDS SRN BAJA AND NRN MEXICO. A JET STREAM BRANCH IS OBSERVED HERE THROUGH 17N126W 21N116W TO 24N107W WITH MAX WIND OF 60-70 KT. THE TAIL END OF AN UPPER LEVEL TROUGH IS OVER THE FAR SW CARIBBEAN SEA AND EXTENDS SW TO PANAMA. NWP MODELS CONTINUE TO FORECAST THE RIDGE TO MIGRATE WWD WITHIN THE NEXT FEW DAYS AS HEIGHTS LOWER OVER MEXICO AND THE GULF OF MEXICO...WHILE THE TROUGH LIFTS NE AND DAMPENS OUT OVER THE NRN CARIBBEAN. MID/UPPER LEVEL FLOW THEN BECOMES ZONAL OVER JUST ABOUT THE ENTIRE DISCUSSION AREA...EXCEPT FOR THE FAR NW CORNER WHERE IT WILL BE UNDER THE AFFECTS OF THE UPPER LEVEL LOW NEARING THAT PORTION OF THE AREA. GAP WINDS...QUIKSCAT DATA FROM EARLIER THIS EVENING SHOWED LIGHT WINDS ALONG THE SRN COAST OF CENTRAL AMERICA WITH ONLY 10 KT WINDS IN THE GULF OF PAPAGAYO. WILL DROP MENTION OF 20 KT WINDS IN THE GULF OF PAPAGAYO FOR THE 0430 UTC HIGH SEAS FORECAST. $$ AGUIRRE