000 AXPZ20 KNHC 092205 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 2205 UTC SUN DEC 09 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 COAST OF COLOMBIA AT 08N77W ACROSS THE SOUTHERN COASTS OF PANAMA AND COSTA RICA TO 09N84W...AND SW TO 08N94W WHERE IT ENDS. A SURFACE TROUGH EXTENDS FROM 12N96W TO 06N101W. JUST TO ITS W...LOW LEVEL WINDS SUGGEST THAT AN ITCZ AXIS BEGINS AT 06N106W...AND CONTINUES TO 08N124W TO 07N140W. ANOTHER SURFACE TROUGH IS NOTED JUST TO THE N OF THE ITCZ FROM NEAR 12N113W TO 08N118W. SCATTERED TSTMS ARE S OF THE ITCZ WITHIN 45 NM OF 05N80W. ISOLATED MODERATE TO STRONG CONVECTION FLARES UP INTERMITTENTLY ALONG THE SECOND TROUGH FROM 12N113W TO 08N118W. MODEL GUIDANCE CONTINUES TO SUGGEST THAT A SURFACE LOW WILL DEVELOP ALONG THE TROUGH THAT EXTENDS ALONG 12N96W TO 06N101W. SCATTEROMETER DATA AND NIGHT CHANNEL IMAGERY CONFIRMS A NE-SW TROUGH IN CONTRAST TO CLOSED SURFACE LOW. ALTHOUGH A LOW CENTER MAY CLOSE OFF AT LEAST INTERMITTENTLY...VERY UNFAVORABLE UPPER LEVEL WINDS TO ITS W AND NW WILL HAMPER IT FROM BECOMING ORGANIZED INTO A SUBSTANTIAL LOW PRES SYSTEM. GUIDANCE INDICATES THAT THIS FEATURE IS LIKELY TO GENERATE ONLY NE-E-SE WINDS AT 15-20 KT...MAINLY IN ITS NRN PERIPHERY WITH SEAS ONLY TO 5-7 FT. ...DISCUSSION... ALOFT...A LONGWAVE UPPER RIDGE DOMINATES THE EASTERN N PACIFIC. AN UPPER SHORTWAVE TROUGH DISSECTS N AMERICA CONTINUING INTO THE DISCUSSION AREA ALONG 32N114W AND SW TO 26N132W TO A SMALL UPPER CYCLONE BECOMING DIFFUSE AT 24N140W. THE UPPER TROUGH IS MERGING WITH THE REMNANTS OF ANOTHER UPPER TROUGH OVER THE ENTIRE AREA N OF 10N BETWEEN 116-130W. AN UPPER ANTICYCLONE IS OVER THE DEEP TROPICS AT 08N140W WITH A SHORTWAVE RIDGE EXTENDING NNE TO A CREST AT 23N136W. UPPER DEBRIS MOISTURE...ORIGINATING FROM THE ITCZ RELATED CONVECTION DESCRIBED BETWEEN 131W-140W...AND CONVECTION W OF 140W IS BEING ADVECTED NE BUT MOST OF THE MOISTURE REMAINS WITHIN THE ANTICYCLONIC ENVELOPE TO THE S OF 21N W OF 130W. AN UPPER ANTICYCLONE IS QUASI-STATIONARY OVER THE DEEP TROPICAL PACIFIC AT 09N91W WITH AN UPPER RIDGE EXTENDING N NW TO A GENTLE CREST FROM 25N110W TO BEYOND 32N103W. A DENSE MOISTURE PLUME CONSISTING OF SCATTERED TO BROKEN HIGH CIRRUS CLOUDS IS OBSERVED OVER THE NE PORTION OF THE DISCUSSION AREA WITHIN 90 NM OF A LINE FROM 26N130W TO 27N119W TO BEYOND 32N104W. DEBRIS MOISTURE FROM ITCZ CONVECTION AND THE LOW LEVEL TROUGH ALONG 12N113W 8N118W IS ADVECTED N ALONG THE NW PERIPHERY OF THE UPPER RIDGE...ROUGHLY WITHIN 210 NM OF A LINE FROM THE PACIFIC AT 15N108W TO ACROSS NRN MEXICO...THEN TURNS EWD TO ACROSS THE NORTHERN GULF OF MEXICO AND SE CONUS. IN CONTRAST...THE UPPER LEVELS APPEAR VERY DRY OVER THE DISCUSSION AREA S OF 17N E OF 102W INCLUDING THE IMMEDIATE ENVIRONMENT OF THE TROUGH ALONG 12N96W 06N101W...CONTINUING TO SUPPRESS CONVECTION EXCEPT FOR THE ACTIVITY AT THE LOW LEVELS...A COLD FRONT OVER THE SW U.S. WILL PUSH SE THROUGH THE GULF OF CALIFORNIA TONIGHT INTO MON. THE PRES GRADIENT IN ITS WAKE WILL RESULT IN WINDS BECOMING N-NE 10-15 KT ALONG THE W COAST OF THE BAJA PENINSULA TONIGHT INTO MON. LIGHT AND VARIABLE WINDS CURRENTLY OVER THE NRN GULF OF CALIFORNIA WILL BECOME NW 20-30 KT BEHIND THE FRONT TONIGHT...THEN DIMINISH TO 15-25 KT WITH THESE CONDITIONS SPREADING S ACROSS THE ENTIRE GULF THROUGH MON NIGHT. EXPECT SEAS MAY BUILD TO 5-8 FT BRIEFLY IN THE NRN GULF WATERS MON IN THE AREAS OF LONG NW FETCH...AND 3-6 FT IN THE SOUTHERN GULF WATERS BY LATE MON NIGHT. THESE NW WINDS SHOULD DIMINISH TO 10-15 KT OVER THE WATERS S OF 29N ON TUE NIGHT...AND BECOME LIGHT AND VARIABLE OVER THE WATERS N OF 29N. OVER THE PACIFIC A SURFACE RIDGE EXTENDS FROM 32N135W TO 16N103W. NORTHEASTERLY 15-20 KT SURFACE WINDS ARE OBSERVED W OF LINE FROM 32N121W TO 08N140W...WITH COMBINED SEAS 6-9 FT IN NE SWELL THAT IS MIXING WITH N SWELL IN THE WATERS N OF 25N E OF 130W. THE SEAS ARE EXPECTED TO INCREASE BRIEFLY TO 9-10 FT OVER THE WATERS N OF 28N W OF 134W TONIGHT. THE GRADIENT WILL RELAX ON MON AND TUE WITH A COLD FRONT EXPECTED TO MOVE INTO THE N CENTRAL WATERS ON TUE NIGHT...PASSING ACROSS THE NORTHERN BAJA PENINSULA ON THU ACCOMPANIED BY A 15-20 KT SW-W-NW WIND SHIFT. SEAS WILL BUILD TO 7-10 FT BEHIND THE FRONT WITH THESE CONDITIONS ARRIVING AT THE NORTHERN BAJA CALIFORNIA PENINSULA ON FRI. WINDS WILL BECOME SOUTHERLY AT 5-10 KT OVER THE NORTHERN GULF OF CALIFORNIA ON WED...INCREASING TO 15-20 KT WED EVENING...BECOMING S-SW AT 20-30 KT LATE WED NIGHT IN ADVANCE OF THE COLD FRONT PASSING ACROSS THE NORTHERN GULF OF CALIFORNIA WATERS LATE THU NIGHT. GAP WINDS... GULF OF TEHUANTEPEC...A COLD FRONT WILL ENTER THE NW GULF OF MEXICO LATE TONIGHT. THE ASSOCIATED NLY WINDS WILL SURGE AT 15-20 KT THROUGH THE CHIVELA PASS TUE NIGHT...GRADUALLY INCREASING WED...REACHING GALE FORCE LATE WED...WITH MINIMAL GALE CONDITIONS EXPECTED TILL A FEW HOURS AFTER SUNRISE ON THU. NOTE THAT MODEL GUIDANCE HAS BEEN FLUCTUATING ON THE STRENGTH OF THIS NEXT TEHUANTEPEC EVENT. WILL CONTINUE WITH PREVIOUS THINKING WITH REGARDS TO THE SEA SURFACE AND MARINE LAYER IN/DOWNSTREAM OF THE GULF OF TEHUANTEPEC BEING COOLER THAN THE SURROUNDING AREAS TO THE E AND W. SINCE THE LOW LEVEL WINDS ARE FORECAST TO REMAIN LIGHT AT 5-10 KT FROM THE S-SW THROUGH MON NIGHT...WOULD EXPECT THE COOLER OCEANIC AND ATMOSPHERIC ENVIRONMENT TO MAINTAIN SOMEWHAT. THUS WOULD EXPECT THE MAXIMUM SEA HEIGHTS ON WED TO BE SIGHTLY LESS THAN THE PREVIOUS TEHUANTEPEC EVENTS. GULF OF PAPAGAYO...NE WINDS WILL CONTINUE TO PULSE AT 10-15 KT WITH AN OCCASIONAL SURGE TO 15-20 KT AS CONFIRMED BY ASCAT/OSCAT PASSES FROM TODAY...IN AND DOWNSTREAM OF THE GULF OF PAPAGAYO THROUGH THE MIDDLE OF THE UPCOMING WEEK...WITH GUIDANCE SUGGESTING AN INCREASE TO 20-25 KT BEGINNING LATE WED NIGHT. $$ AGUIRRE