000 AXPZ20 KNHC 081551 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC SAT DEC 08 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... THE MONSOON TROUGH EXTENDS W FROM THE NW COAST OF COLOMBIA ACROSS THE PANAMA/COSTA RICA BORDER TO 09N89W...THEN TURNS SW THROUGH AN EMBEDDED 1009 MB LOW PRESSURE CENTER AT 07N94W TO 07N100W WHERE LOW LEVEL WINDS INDICATE A TRANSITION TO AN ITCZ. THE ITCZ CONTINUES NW TO 09N109W...THEN WIGGLES WESTWARD BETWEEN 07-09N TO BEYOND 07N140W. ISOLATED MODERATE TO STRONG THUNDERSTORMS WITH OCCASIONAL LIGHTNING IS OBSERVED WITHIN 30 NM OF 05.5N79W AND 07.5N84W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED WITHIN 90 NM EITHER SIDE OF A LINE FROM 10N125W TO 08N140W. ...DISCUSSION... ALOFT...A LONGWAVE UPPER RIDGE HAS ITS MEAN AXIS ANCHORED OVER THE N PACIFIC ALONG 150W. A COUPLE OF UPPER SHORTWAVE TROUGHS ARE SWINGING SE INTO THE AREA E OF THE RIDGE. THE WESTERNMOST TROUGH EXTENDS FROM 34N114W TO TO 31.5N130W AND INTO A MID/UPPER CYCLONE AT 27N142W WHICH OCCASIONALLY INDUCES A SURFACE TROUGH OVER THE FAR NW WATERS. THE EASTERNMOST SHORTWAVE EXTENDS ALONG 32N105W TO 26N117W...THEN TURNS SW TO BASE OVER THE DEEP TROPICS AT 11N126W. AN UPPER ANTICYCLONE OVER THE TROPICS AT 07N148W HAS A SHORTWAVE RIDGE EXTENDING NE BETWEEN THE TWO SHORTWAVE TROUGHS...TO A SHARP CREST AT 21N126W. DENSE UPPER MOISTURE IS NOTED UNDER THIS RIDGE...WITHIN 150 NM EITHER SIDE OF A LINE FROM 17N134W TO 26N128W WHERE IT SPREADS OUT OVER THE DISCUSSION AREA FROM 26-31N...W OF 120W TO THE UPPER CYCLONE AT 27N142W. THIS MOISTURE PLUME WILL LIKELY MOVE E ACROSS THE NORTHERN BAJA PENINSULA LATER TODAY IN STRONG UPPER ZONAL FLOW. DRY UPPER AIR ACCOMPANIES THE EASTERNMOST TROUGH WITHIN 240 NM EITHER SIDE OF A LINE FROM 12N125W TO 23N122W...THEN THE BAND OF DRY AIR NARROWS AS IT TURNS NE ACROSS THE CENTRAL BAJA PENINSULA TO ACROSS NORTHERN MEXICO AND NORTHERN TEXAS. A LONGWAVE UPPER TROUGH DOMINATES N AMERICA WITH ITS MEAN AXIS ALONG 100W...BUT NOW SEEMS TO BE FILLING WITH UPPER ZONAL WINDS NOTED AS FAR S AS THE CENTRAL GULF OF MEXICO. AN UPPER ANTICYCLONE IS QUASI-STATIONARY OVER THE DEEP TROPICAL PACIFIC AT 07N90W WITH AN UPPER RIDGE EXTENDING NW TO A CREST AT 23N118W. THIS PATTERN SETS UP AN AREA OF UPPER DIFFLUENCE ENHANCING THE CONVECTION PREVIOUSLY DESCRIBED BETWEEN 110-118W. THE RESULTANT DEBRIS MOISTURE CONTINUES TO BE ADVECTED N ALONG THE W PERIPHERY OF THE UPPER RIDGE...ROUGHLY WITHIN 240 NM OF A LINE FROM 11N114W TO 26N114W. THIS MOISTURE PLUME THEN TURNS E-NE ACROSS THE UPPER RIDGE AXIS...THINNING SOMEWHAT AS IT CONTINUES NORTHEASTWARD TO THE E OF THE LONGWAVE TROUGH AXIS... AND ACROSS THE NW GULF OF MEXICO AND THE SE CONUS...EVENTUALLY FEEDING INTO THE CONVECTION FLARING OVER THE GULF STREAM E OF THE CAROLINAS. THE UPPER LEVELS APPEAR VERY DRY OVER THE DISCUSSION AREA S OF 17N E OF 104W...SUPPRESSING CONVECTION EXCEPT FOR THE SMALL CLUSTERS PREVIOUSLY MENTIONED S OF PANAMA. AT THE LOW LEVELS...A SURFACE RIDGE EXTENDS FROM 32N134W TO 17N105W. NORTHERLY WINDS ARE OBSERVED AT 15-20 KT TO THE NE OF THE RIDGE...IN THE AREA N OF 27N BETWEEN 120-128W...WITH SEAS 8-9 FT IN MIXED NE AND NW SWELL. THESE WINDS ARE EXPECTED TO BRIEFLY DIMINISH TO 15 KT AND THE SEAS SUBSIDE TO 7 FT LATE TODAY AND TONIGHT. THE TRADES SW OF THE RIDGE ARE AT 15-20 KT IN THE AREA FROM 08-22N W OF 125W...WITH SEAS 7-9 FT IN PRIMARILY IN MIXING NE AND NW SWELL. THE GRADIENT IS EXPECTED TO TIGHTEN ON SUN WITH NE 15-20 KT WINDS COVERING THE WATERS NW OF LINE FROM 32N120W TO 11N140W WITH SEAS 7-9 FT IN MOSTLY NE SWELL. EXPECT NW WINDS AT 5-10 KT WITH SEAS 3-5 FT ALONG THE W COAST OF THE BAJA CALIFORNIA THROUGH SUN MORNING. A COLD FRONT WILL SWEEP S INTO THE EXTREME NE WATERS...INCLUDING THE GULF OF CALIFORNIA ON SUN AFTERNOON. THIS WILL RESULT IN WINDS BECOMING NE 15-20 KT ALONG THE W COAST OF THE BAJA PENINSULA LATE SUN NIGHT INTO MON. LIGHT AND VARIABLE WINDS OVER THE NORTHERN GULF OF CALIFORNIA TODAY WILL BECOME NW BEHIND THE FRONT...INCREASING TO 20-25 KT IN THE NORTHERN GULF WATERS...BRIEFLY 25-30 KT LATE SUN NIGHT...WITH NW WINDS AT 15-25 KT SPREADING S ACROSS THE ENTIRE GULF BY MON NIGHT. EXPECT SEAS MAY BUILD TO 6-9 FT BRIEFLY IN THE NORTHERN GULF WATERS MON IN THE AREAS OF LONG NW FETCH...AND 4-6 FT SOUTHERN GULF WATERS BY LATE MON NIGHT. THESE NW WINDS SHOULD DIMINISH TO 10-15 KT TUE NIGHT. GAP WINDS... GULF OF TEHUANTEPEC...A COLD FRONT WILL ENTER THE NW GULF OF MEXICO SUN NIGHT. THE ASSOCIATED NORTHERLY WINDS WILL SURGE AT 15-20 KT THROUGH THE CHIVELA PASS TUE AFTERNOON...WITH WINDS GRADUALLY INCREASING TUE NIGHT AND EARLY WED...REACHING NEAR GALE FORCE BY LATE WED...AND CONTINUING INTO MIDDAY THU. NOTE THAT LATEST MODEL GUIDANCE IS NOT AS AGGRESSIVE AS PREVIOUS RUNS. GULF OF PAPAGAYO...NE WINDS WILL CONTINUE TO PULSE AT 10-15 KT IN AND DOWNSTREAM OF THE GULF OF PAPAGAYO THROUGH THE MIDDLE OF NEXT WEEK...WITH GUIDANCE SUGGESTING AN INCREASE TO 20-25 KT BEGINNING ON WED NIGHT. $$ NELSON