000 AXPZ20 KNHC 101537 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1535 UTC WED OCT 10 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 1500 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS W FROM 11.5N86W TO LOW PRES 1009 MB NEAR 12N99W TO 11N125W. ITCZ EXTENDS FROM 10N129W TO 06N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION WITHIN 60 NM EITHER SIDE OF MONSOON TROUGH AXIS BETWEEN 85W AND 100W. SCATTERED MODERATE CONVECTION WITHIN 90 NM N OF ITCZ AXIS W OF 130W. ...DISCUSSION... W OF 110W...A WEAK COLD FRONT EXTENDING FROM SOUTHERN CALIFORNIA TO NEAR 27N127W TO 30N134W WILL MAKE ONLY SLOW PROGRESS TO THE SOUTHEAST BEFORE STALLING AND DISSIPATING...AS THE PARENT UPPER LOW CURRENTLY OFF THE COAST OF CENTRAL CALIFORNIA PUSHES SE AND ONSHORE ACROSS SOUTHERN CALIFORNIA OVER THE NEXT 48 HOURS. A SECOND FRONT WILL CLOSELY ON THE HEELS OF THE CURRENT FRONT...EMERGING OUT OF THE N CENTRAL PACIFIC BY FRI SUPPORTED BY A SHORT WAVE TROUGH MOVING W OF 140W N OF 30N BY LATE THU. THE GFS AND ECMWF ARE IN CLOSE AGREEMENT DEPICTING THE SECOND FRONT AS FAIRLY WEAK...SERVING ONLY TO FLATTEN THE RESIDENT SURFACE RIDGE ALONG 28N. THIS IN TURN WILL MAINTAIN 15 TO 20 KT FLOW BETWEEN THE SURFACE RIDGE AND THE REMNANT LOW OF OLIVIA CENTERED NEAR 13N125W. AN EARLIER ASCAT PASS HINTED THAT WINDS ARE STILL PROBABLY NEAR 20 TO 25 KT WITHIN 240 NM OF THE LOW PRES...BUT THIS IS DIMINISHING AS THE LOW DISSIPATES AND BECOMES A WEAK TROUGH BY THU. THE MODERATE TO FRESH TRADE WIND FLOW IS ENOUGH TO ENHANCE CONVECTION TO THE NORTH OF THE ITCZ W OF 130W. SHIP DHOE REPORTED N WINDS AT 20 KT OFF THE COAST OF CENTRAL BAJA NEAR PUNTA EUGENIO...ON THE EASTERN EDGE OF THE SURFACE HIGH PRES. 15 TO 20 KT WINDS WILL PERSIST OFF THE BAJA COAST INTO THU...THEN DIMINISH AS THE FRONT DISSIPATES. SW WINDS TO 20 KT ARE LIKELY OVER THE NORTHERN GULF OF CALIFORNIA THU AND FRI HOWEVER AS THE SUPPORTING UPPER LOW MIGRATES INTO SOUTHERN CALIFORNIA. NW SWELL CONTINUES TO PROPAGATE INTO THE AREA FROM THE N CENTRAL PACIFIC. WAVEWATCH...EC WAVE AND UKMET WAVE OUTPUT INDICATE SIGNIFICANT WAVE HEIGHTS REACHING 8 TO 11 FT IN MIXED NW AND NE SWELL OVER MUCH OF THE AREA N OF 08N AND W OF 125W. E OF 110W... A WEAK CIRCULATION IS FORMING ALONG THE MONSOON TROUGH NEAR 12N99W...AIDED IN PART FROM ADDED VORTICITY PROVIDED BY THE PREVIOUS TEHUANTEPEC EVENT OVER THE PAST COUPLE OF DAYS. CONVECTION IS NOT ESPECIALLY DEVELOPED OR ORGANIZED AT THIS TIME...WITH ONLY MODERATE SW FLOW FEEDING INTO THE MONSOON TROUGH. THE 10/00Z ECMWF HAS BEEN MOST AGGRESSIVE DEVELOPING THIS LOW PRES AREA AND MIGRATING IT TO THE WNW. THE LATEST GFS IS A BIT WEAKER HOWEVER INTO THU...AND SEEMS MORE PLAUSIBLE GIVEN THE WEAK STATE OF THE LOW PRES CURRENTLY AND LACK OF STRONG CONVERGENCE INTO THE LOW. MEANWHILE GFS IS SHOWING A WIND PULSE TO 20 KT THROUGH THE GULF OF TEHUANTEPEC DUE TO DRAINAGE EFFECTS LATE TONIGHT AND EARLY TOMORROW MORNING. A SLIGHTLY STRONGER AND MORE PERSISTENT PULSE WILL REPEAT THU NIGHT INTO FRI MORNING AIDED BY REINFORCING HIGH PRES IN THE GULF OF MEXICO. THIS MAY PROVIDE ADDED IMPETUS TO THE DEVELOPING LOW FRI INTO SAT BY THEN NEAR 13N100W...AND THE GFS COMES INTO A LITTLE BETTER AGREEMENT WITH THE ECMWF...BUT NOT AS STILL AGGRESSIVE. GIVEN THE TRACK INTO COOLER WATERS BY THAT TIME...FORECAST FAVORS MORE CONSERVATIVE GFS. $$ CHRISTENSEN