000 AXPZ20 KNHC 122150 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 2205 UTC WED DEC 12 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2145 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS W FROM THE COLOMBIAN COAST AT 07N78W TO 07N96W...THEN TURNS NW TERMINATING AT AN EMBEDDED 1011 MB LOW PRESSURE CENTER AT 10.5N105W. LOW LEVEL WINDS INDICATE THAT THE ITCZ FORMS SW OF THE LOW PRESSURE CENTER NEAR 09N106W AND CONTINUES WESTWARD ALONG 07N110W TO 09N128W TO BEYOND 09N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS OBSERVED WITHIN 120 NM EITHER SIDE OF A LINE FROM 06.5N79W TO 07N90W. ISOLATED SHOWERS ARE NOTED WITHIN 150 NM OF 08N97W AND WITHIN 120 NM OF THE ITCZ W OF 125W. THE EMBEDDED SURFACE LOW AT 10.5N105W HAS LOST ALL SIGNIFICANT CONVECTION AND SHOULD SOON WEAKEN TO AN OPEN TROUGH AS IT CONTINUES WESTWARD. ...DISCUSSION... ALOFT...A BROAD UPPER LEVEL TROUGH DOMINATES THE DISCUSSION AREA N OF 22N BETWEEN 113-140W AND IS BEING REINFORCED BY A SECONDARY TROUGH CURRENTLY ALONG 32N123W TO 26N140W. UPPER MOISTURE IS NOTED N OF 29N TO THE E OF THIS THIS SECONDARY TROUGH...AND IS ADVECTED NE ACROSS SOUTHERN CALIFORNIA AND ARIZONA. OTHERWISE STRONG UPPER LEVEL WESTERLIES AND DRY UPPER AIR IS OBSERVED N OF 22N ACROSS FROM ACROSS MEXICO TO 140W. A COUPLE OF UPPER TROUGHS ARE EVIDENT TO THE S OF 18N BETWEEN 102-123W. AN UPPER ANTICYCLONE IS CENTERED NEAR 01N134W WITH ANTICYCLONIC FLOW OBSERVED S OF 13N BETWEEN 123-144W...WITH DRY UPPER AIR TRAPPED UNDER THE RIDGE TO THE S OF 10N W OF 124W SUPPRESSING CONVECTION ALONG THE ITCZ. AN SMALL UPPER ANTICYCLONE IS CENTERED NEAR 11N98W AND REMNANTS OF ANOTHER UPPER TROUGH STRETCH NE-SW FROM BELIZE TO THE EQUATOR AT 97W. A FEW CONVECTIVE CELLS ARE ENHANCED NEAR THE TROUGH AT 08N. AN UPPER ANTICYCLONE IS QUASI-STATIONARY OVER S AMERICA AT 07N72W WITH A RIDGE EXTENDING W CRESTING ALONG 05N90W TO 10N90W TO 13N87W. THE ASSOCIATED UPPER DIFFLUENCE IS ENHANCING CONVECTION ALONG THE MONSOON TROUGH AS PREVIOUSLY DESCRIBED...WITH THE RESULTANT DEBRIS MOISTURE NOW ADVECTED NE UNDER THE RIDGE ACROSS CENTRAL AMERICA TO THE W OF 90W. THE UPPER FLOW IS ZONAL ACROSS THE TROPICS FROM 10-22N TO THE W OF 105W. THESE STRONG WESTERLIES CONTINUE TO ADVECT DENSE UPPER MOISTURE MOSTLY ORIGINATING IN THE CENTRAL PACIFIC EASTWARD TO ALONG 105W. THIS MOISTURE PLUME THEN TURNS NE IN RESPONSE TO A LONGWAVE TROUGH OVER THE CENTRAL CONUS. THIS MOISTURE FEEDS INTO THE CONVECTION ALONG A STATIONARY FRONT EXTENDING SW FROM N FLORIDA TO THE BAY OF CAMPECHE IN THE SOUTHERN GULF OF MEXICO. ELSEWHERE AT THE LOW LEVELS...A COLD FRONT EXTENDS FROM 32N128W TO 28N140W WITH A RIDGE WEAKENING JUST TO THE S OF THE FRONT. NE WINDS AT 20-30 KT...SEAS 8-11 FT...ARE OBSERVED W OF A LINE FROM 32N127W TO 24N140W. NE 15-20 KT TRADES ARE ALSO ENHANCED SW OF THE RIDGE FROM 08-17N W OF 135W WITH SEAS OF 6-8 FT. THE COLD FRONT IS EXPECTED TO CONTINUE E REACHING FROM 32N116W TO 24N123W ON THU AND THEN BEGIN TO WEAKEN AS IT PASSES ACROSS THE BAJA PENINSULA AND THE GULF OF CALIFORNIA ON FRI. POST FRONTAL NE WINDS AT 20-25 KT...SEAS 7-11 FT...WILL SPREAD EASTWARD ACROSS THE WATERS W OF A LINE FROM 32N120W TO 20N137W ON THU. THE GRADIENT WILL WEAKEN ON FRI WITH NW-N WINDS AT 10-15 KT ACROSS THE PACIFIC WATERS N OF 24N W OF 116W WITH SEAS 7-10 FT IN NW SWELL. THE TRADES WILL ALSO DIMINISH TO 15-20 KT ACROSS THE WATERS FROM 12-23N W OF 129W WITH SEAS 7-9 FT IN MIXED N SWELL. GENERALLY EXPECT SEAS OF 3-5 FT ALONG THE WESTERN BAJA PENINSULA THROUGH LATE THU...THEN SEAS WILL BUILD TO 5-8 FT IN THE NW SWELL FROM THU NIGHT INTO EARLY FRI ACROSS THE BAJA COASTAL WATERS TO THE N OF 27N. LIGHT AND VARIABLE WINDS CURRENTLY ACROSS THE GULF OF CALIFORNIA WILL BECOMING SOUTHERLY TONIGHT AND INCREASE 20-25 KT OVER THE NORTHERN WATERS EARLY THU AHEAD OF THE COLD FRONT. THE POST FRONTAL NORTHERLY FLOW IS NOT EXPECTED TO BE VERY STRONG ACROSS THE GULF OF CALIFORNIA... GENERALLY IN THE 10-15 KT RANGE...FRI NIGHT AND SAT THEN INCREASING TO 15-20 KT ACROSS THE GULF WATERS S OF 26N ON SUN. GAP WINDS... GULF OF TEHUANTEPEC...STRONG N WINDS WILL INCREASE TO A MINIMAL GALE AROUND SUNRISE THIS EVENING AND FURTHER INCREASE TO 35-40 KT LATE TONIGHT...WITH THE FINAL GALE SURGE EXPECTED JUST AFTER SUNRISE ON THU. N WINDS EXPECTED AT 20-30 KT EXPECTED FROM THU NIGHT THROUGH SUNRISE FRI...THEN WINDS WILL QUICKLY DIMINISH. BEST GUESS IS THE NEXT NEAR GALE NORTHERLY EVENT WILL BEGIN LATE MON NIGHT AND CONTINUE THROUGH WED MORNING. GULF OF PAPAGAYO...NE WINDS WILL CONTINUE TO PULSE AT 15-20 KT WITH AN OCCASIONAL SURGES TO 20-25 KT THROUGH THU AFTERNOON AND REACH AS FAR SW OF THE GULF OF PAPAGAYO AS 09.5N91W. GUIDANCE SUGGESTS WINDS WILL REMAIN IN THE 10-15 KT RANGE WITH PULSES TO 15-20 KT FROM THU NIGHT THROUGH THE MIDDLE OF NEXT WEEK. $$ NELSON