000 AXPZ20 KNHC 241603 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC SAT MAR 24 2012 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL ANALYSIS. BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1545 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... ITCZ AXIS EXTENDS FROM 08N111W TO 08N123W TO 05N130W TO 04N140W. NO SIGNIFICANT CONVECTION IS NOTED. ...DISCUSSION... A RATHER VIGOROUS DEEP LAYERED TROUGH N OF 24N BETWEEN 120W AND 136W HAS WITH A MEAN AXIS EXTENDING THROUGH 32N130W TO 26N135W TO W OF THE AREA AT 24N140W AS SEEN ON WATER VAPOR IMAGERY. THE TROUGH IS SUPPORTING A COLD FRONT THAT ENTERS THE DISCUSSION AREA NEAR 32N125W AND EXTENDS SW TO 28N130W WHERE IT BEGINS TO WEAKEN TO 25N140W. THE UPPER TROUGH WILL TRANSLATE EASTWARD REACHING THE U.S. W COAST SUN NIGHT. COLD AIR ADVECTION AS MARKED BY THE STRATOCUMULUS CLOUD FIELDS NOTED ON SATELLITE IMAGERY PRESSING SEWD JUST N OF THE AREA WILL SWEEP INTO THE AREA BEHIND THE FRONT. THIS WILL BE REFLECTED AS NW TO N 20 KT WINDS BEHIND THE FRONT...GRADUALLY INCREASING TO W TO NW 20-30 KT N OF 28N WITHIN 450 NM W OF THE COLD FRONT BY EARLY SUN AS THE FRONT REACHES A PSN FROM 32N121W TO NEAR 23N131W WHILE AT THE SAME TIME IT UNDERGOES WEAKENING WITH THE UPPER SUPPORT PULLING FURTHER AWAY FROM THE REGION. W TO NW WINDS IN THE GALE FORCE RANGE ARE EXPECTED TO SKIRT JUST TO THE N OF THE AREA ON SUN AS LOW PRES ASSOCIATED WITH THE FRONTAL SYSTEM DIVES SEWD TO NEAR 32N126W BEFORE TURNING MORE EASTWARD AND WEAKENING WITH THE ATTENDANT COLD FRONT AS IT APPROACHES SRN CALIFORNIA SUN NIGHT. BY SUN...THE COLD FRONT WILL BE DISSIPATING FROM NEAR 32N117W TO 26N121W. IN ADDITION TO THE INCREASING WINDS BEHIND THE FRONT...WAVEWATCH MODEL GUIDANCES ARE CONSISTENTLY SUGGESTING THAT LONG PERIOD NW SWELLS SPREADING INTO THE NW PORTION OF THE AREA BEHIND THE FRONT WILL LEAD TO VERY LARGE SEA HEIGHTS...POSSIBLY IN THE RANGE OF 14-21 FT N OF 28N IN 24 HRS TO THE N OF 28N AND WITHIN 450 NM W OF THE COLD FRONT...AND WITH SEAS 12-19 FT ELSEWHERE W OF THE FRONT. SEAS WILL ONLY SLOWLY SUBSIDE INTO MON AS WEAK HIGH PRES BUILDS OVER MUCH OF THE AREA N OF 18N. ELSEWHERE IN THE UPPER LEVELS...GENERALLY ZONAL FLOW EXISTS BEHIND A A MID LEVEL SHORTWAVE RIDGE ALONG 112W N OF 112W THAT IS SLIDING EASTWARD WITH TIME. AHEAD OF THE RIDGE...THE UPPER FLOW PATTERN IS SW TO W. SCATTERED TO BROKEN HIGH CLOUDS ARE STREAMING EASTWARD INTO THE AREA WITH THE ZONAL FLOW AS NOTED FROM 04N TO 22N W OF 127W. A RATHER PERSISTENT SURFACE TROUGH IS OBSERVED TO EXTEND FROM 09N84W TO 04N95W. CONVERGENCE ASSOCIATED WITH THE TROUGH HAS AGAIN INCREASED...WITH RESULTANT CONVECTION DEPICTED AS THE SCATTERED MODERATE/ISOLATED STRONG TYPE WITHIN 180 NM SE OF THE TROUGH BETWEEN 84W-86W. EXPECT THE TROUGH TO LINGER THROUGH THE NEXT 48 HRS. A WEAK SURFACE TROUGH NEAR 102W FROM 06 TO 10N IS SOMEWHAT DISCERNIBLE ON FIRST VISIBLE IMAGES FROM THIS MORNING...AND AS HINTED BY THE TPW (TOTAL PRECIPITABLE WATER IMAGERY) FROM CIMSS. THIS TROUGH IS EXPECTED TO TRACK WWD OVER THE NEXT COUPLE OF DAYS WITH ONLY ISOLATED SHOWERS AND WEAK ISOLATED TSTMS EXPECTED NEAR IT. ISOLATED SHOWERS AND WEAK CONVECTION IS ALONG AND WITHIN 120 NM N OF THE ITCZ BETWEEN 111W AND 120W WHERE A WEAK DISTURBANCE IN THE UPPER ZONAL FLOW IS HELPING TO SUSTAIN THIS ACTIVITY. THE SURFACE RIDGE THAT PREVAILED ACROSS THE AREA DURING THE PAST FEW DAYS HAS WEAKENED WITH THE COLD FRONT NOW MAKING HEADWAY ACROSS THE N/CENTRAL PORTION OF THE AREA. A VERY WEAK PRES GRADIENT S OF THE RIDGE IS ONLY ALLOWING FOR A VERY SMALL AREA OF NE 20 KT WINDS AS BEST DEFINED FROM 11N TO 20N W OF 134W WITH SEAS OF 8 FT. THESE TRADE WINDS WILL GRADUALLY DIMINISH BY LATE SUN NIGHT OR EARLY MON MORNING. NE 20 KT PAPAGAYO WINDS NOTED LAST NIGHT ON OSCAT DATA ARE FORECAST TO LESSEN TO LESS THAN 20 KT THIS AFTERNOON. $$ AGUIRRE