000 AXPZ20 KNHC 282121 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 2205 UTC MON APR 28 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 2100 UTC. ...ITCZ... ITCZ AXIS RUNS FROM 05N77W TO 7N92W TO 4N104W TO 6N120W TO 2N133W TO 1N140W. SCATTERED MODERATE AND EMBEDDED ISOLATED STRONG CONVECTION IS FROM 1N TO 6N BETWEEN 88W AND 108W. SCATTERED MODERATE CONVECTION IS WITHIN 180 NM N OF THE AXIS BETWEEN 121W AND 126W. ...DISCUSSION... E OF 115W... A LATE SEASON STRONG COLD FRONT HAS PUSHED S INTO THE BAY OF CAMPECHE WITH A COOL HIGH PRES AIRMASS SURGING S NEAR THE TEXAS/MEXICO BORDER. THIS SYNOPTIC PATTERN IS PRODUCING GALE CONDITIONS BEHIND THE FRONT IN THE SW GULF. N WINDS ARE EXPECTED TO INCREASE SHORTLY OVER THE GULF OF TEHUANTEPEC...AND REACH MINIMAL GALE CRITERIA TONIGHT. NWP MODELS AND CLIMATOLOGY SUGGEST THAT THIS EVENT SHOULD BE SHORT LIVED...LIKELY FALLING BELOW GALE FORCE MIDDAY WED. THE SUPPORT...LARGE SCALE TROUGH... FOR THE FRONT EXTENDS ACROSS MEXICO AND REACHES A BASE NEAR 20N112W. UPPER CONFLUENCE ALONG AND TO THE W OF THE AXIS IS PROVIDING A VERY SUBSIDENT ENVIRONMENT FROM 17N-27N. MEANWHILE MOIST SOUTHWEST FLOW ALOFT AHEAD OF THE TROUGH IS PROVIDING THE EXHAUST TO SUPPORT A LARGE AREA OF CONVECTION WITHIN THE ITCZ BETWEEN 88W-108W. OTHERWISE...A PAIR OF SW SWELL GROUPS WITH PERIODS AS LONG AS 17 TO 19 SECONDS WILL PUSH INTO THE AREA THROUGH MID-LATE WEEK. W OF 115W... UPPER PATTERN REMAINS FAIRLY AMPLIFIED N OF 20N WITH A MID/UPPER RIDGE ALONG 118W...AHEAD OF A LARGE AMPLITUDE UPPER TROUGH EXTENDING FROM THE FAR NORTH PACIFIC TO JUST N OF HAWAII. THE PATTERN WILL FLATTEN OUT OVER THE NEXT DAY OR TWO AS THE LARGE UPPER TROUGH SHIFTS E. A 1033 MB SURFACE HIGH CENTERED NEAR 36N154W WILL SHIFT EWD BEHIND THE TROUGH. FRESH TO STRONG NORTH FLOW ALREADY EVIDENT OFF THE CALIFORNIA COAST ON THE EAST EDGE OF THIS SURFACE HIGH WILL INCREASE SLIGHTLY AND EXPAND SOUTHWARD OFF THE NORTHERN BAJA COAST THROUGH MID WEEK AS THE SURFACE HIGH SHIFTS EASTWARD. TRADES TO THE SOUTH OF THE HIGH WILL SLIGHTLY INCREASE AS WELL. FURTHER SOUTH...AND UPPER TROUGH EXTENDS FROM HAWAII TO EQ120W...WITH A PARALLEL UPPER RIDGE AXIS TO ITS NE FROM 10N115W TO 20N145W. SOUTHERLY DIFFLUENT FLOW ALOFT IS PLAYING A MINIMAL ROLE IN THE RELATIVELY MODEST CONVECTION ALONG THE ITCZ W OF 115W...PERHAPS DUE TO LIMITED LOW LEVEL CONVERGENCE DUE TO LIGHT CROSS EQUATORIAL SURFACE WINDS. SOME INCREASE IN CONVECTION IS POSSIBLE ALONG THE ITCZ AS THE UPPER PATTERN CONTINUES THROUGH MID WEEK. MEANWHILE...LONG PERIOD SW SWELL WILL CONVERGE WITH NW SWELL AND MODERATE TO FRESH NORTHERLY AND EASTERLY WIND WAVES TO CREATE POSSIBLE CONFUSED SEA CONDITIONS...MAINLY N OF 20N TOMORROW AND WED. $$ CANGIALOSI