000 AXPZ20 KNHC 171545 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC TUE MAY 17 2011 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1500 UTC. ...ITCZ... AXIS ALONG 08N122W TO 05N140W. NO SIGNIFICANT CONVECTION. MONSOONAL TROUGH AXIS FROM 16N96W TO 08N122W. SCATTERED TO NUMEROUS MODERATE ISOLATED STRONG WITHIN 360 NM SE OF TROUGH AXIS E OF 110W. ...DISCUSSION... UPPER LEVEL TROUGH EXTENDS SW 32N122W TO 21N130W WITH VERY DRY SUBSIDING AIR MASS WITHIN 240 NM NW OF AXIS. DOWNSTREAM E-W STRETCHED RIDGE WITH MULTIPLE ANTICYCLONIC GYRES ALONG 10N DRIVE WIND FLOW OVER REMAINDER OF BASIN. RIDGE PROVIDE UPPER LEVEL FAVORABLE CONDITIONS FOR DEVELOPING TSTMS AS WIND SHEAR IS MINIMIZED AND OUTFLOW KEEPS DEBRIS MOISTURE CIRCULATING IN PLACE FOR FURTHER CONVECTION. MODERATE TO STRONG DIFFLUENCE OVER MONSOONAL SURFACE TROUGH HAS PROMPTED NUMEROUS MODERATE AND ISOLATED STRONG TSTMS N OF 10N FROM 90W-100W AND SCATTERED MODERATE CONVECTION ELSEWHERE WITHIN 360 NM SE OF TROUGH WHICH EXTEND FROM 16N96W TO 08N122W. ...ELSEWHERE AT THE SURFACE.. MAIN FEATURE IN E PAC FOCUS ON MONSOONAL TROUGH EXTENDING SW OUT OF GULF OF TEHUANTEPEC TO 08N122W ATTRACTING STRONG LOW LEVEL WARM AND MOIST AIR MASS...AS MENTIONED IN ABOVE PARAGRAPH. ON THE OTHER HAND...WESTERN PORTIONS OF E PAC WHERE ITCZ COMES INTO PLAY...ARE DEVOID OF MOISTURE HENCE CONVECTION WITH DRY AIR MASS AND ADVERSE ENVIRONMENT ALOFT. LARGE...UP TO 12 FT...LONG PERIOD CROSS EQUATORIAL SWELLS ENCROACH INTO E PAC FROM THE SW AND COVER ENTIRE BASIN BY END OF FORECAST PERIOD. SEA HEIGHTS BEGIN SUBSIDING BY END OF PERIOD. BROAD RIDGE 1023 MB AT 28N148W DRIFT E INTO BASIN EFFECTIVELY KEEPING MODERATE TO FRESH WINDS ALONG TROPICS. WEAK COLD FRONT SCRAPES NORTHERN PORTIONS OF RIDGE NEAR CALIFORNIA BORDER WED INCREASE W TO NW WINDS OVER NORTHERN PORTIONS ON BOTH SIDES OF BAJA CALIFORNIA PENINSULA. $$ WALLY BARNES