000 AXPZ20 KNHC 051549 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC WED DEC 05 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 NW FROM THE COLOMBIAN COAST AT 08N78W ACROSS PANAMA AND COSTA RICA TO THE PACIFIC COAST AT 09N83W... THEN TURNS SW TO 08N91W WHERE LOW LEVEL WINDS INDICATE A TRANSITION TO AN ITCZ WHICH CONTINUES W-SW TO BEYOND 06N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION...WITH OCCASIONALLY LIGHTNING DETECTED...IS OBSERVED WITHIN 90 NM EITHER SIDE OF LINES FROM 05N77W TO 08N84W AND FROM 08N95W TO 08N108W...AND ALSO WITHIN AN AREA BOUNDED BY 06-11N BETWEEN 111-120W. BROKEN-LOCALLY OVERCAST LOW-MID LEVEL CLOUDS WITH ISOLATED SHOWERS IS NOTED ELSEWHERE WITHIN 120 NM OF THE MONSOON TROUGH AND ITCZ AXIS. ...DISCUSSION... ALOFT...AN UPPER CYCLONE IS CENTERED AT 19N130W WITH AN UPPER TROUGH DOMINATING THE DISCUSSION AREA N OF 10N W OF 128W. AN UPPER ANTICYCLONE IS AT 10N90W WITH A RIDGE EXTENDING W-NW THROUGH 24N117W TO A CREST OVER SOUTHERN CALIFORNIA. A DEEP LAYERED CYCLONE IS OVER LOUISIANA WITH AN UPPER TROUGH EXTENDING SW TO A BASE OVER OLD MEXICO AT 20N105W. THIS PATTERN SETS UP AN AREA OF UPPER DIFFLUENCE THAT IS IN PHASE WITH THE ITCZ BETWEEN 100-120W...AND IS ENHANCING THE CONVECTION AS PREVIOUSLY DESCRIBED. THE RESULTANT DENSE UPPER DEBRIS MOISTURE IS ADVECTED N FROM THE ITCZ BETWEEN 118-125W...TURNING E ACROSS THE UPPER RIDGE NEAR 22N118W...THEN CONCENTRATING INTO A NARROW MOISTURE PLUME THAT CONTINUES E ALONG THE BASE OF THE UPPER TROUGH ACROSS CENTRAL OLD MEXICO...AND THE SOUTHERN GULF OF MEXICO. LITTLE CHANGE EXPECTED EXCEPT THAT THE UPPER TROUGH OVER MEXICO WILL DIG FURTHER S OVER THE EASTERN PORTION. AT THE LOW LEVELS...A SURFACE HIGH IS CENTERED NEAR 28N128W WITH A RIDGE EXTENDING SE TO 14N103W AND A RIDGE EXTENDING SW TO 26N140W. SOUTHERLY FLOW ALONG THE PERIPHERY OF THE RIDGE IS AT 15-20 KT TO THE NW OF LINE FROM 32N131W TO 28N140W...WITH COMBINED SEAS 7-8 FT IN MIXING SW WIND WAVE AND LONG PERIOD NW SWELL. THE TRADES SW OF THE WESTERN RIDGE ARE AT 20-25 KT IN THE AREA FROM 06-21N W OF 123W WITH SEAS 7-10 FT IN MIXED SHORT PERIOD NE AND LONG PERIOD NW SWELL. CROSS EQUATORIAL S-SE LONG PERIOD SWELL IS MIXING WITH LONG PERIOD NW SWELL RESULTING IN COMBINED SEAS 7-8 FT IN THE TROPICAL WATERS S OF 05N BETWEEN 105-110W. THE SURFACE HIGH WILL SHIFT NW OF THE AREA ON THU WITH A RIDGE SE TO NEAR 18N107W. A WEAK COLD FRONT WILL ENTER AND STALL OVER THE FAR NW WATERS ON THU BUT ONLY ACCOMPANIED BY A 5-10 KT SW-W-NW WIND SHIFT. A SECOND COLD FRONT WILL STALL JUST NW OF THE AREA LATE FRI. THE AREA OF ENHANCED TRADES SW OF THE RIDGE WILL SHRINK TO 07-21N W OF 125W ON THU...AND FROM 07-21N W OF 132W ON FRI AS THE NE TRADES DIMINISH TO 15-20 KT AND SEAS SUBSIDE TO 6-9 FT IN THE NE SWELL. THE GRADIENT WILL TIGHTEN NE OF THE SURFACE RIDGE...GENERALLY TO THE N OF 28N BETWEEN 117-127W...ON THU NIGHT SUPPORTING NW 15-20 KT AND SEAS 7-9 FT IN NW SWELL. EXPECT NW WINDS AT 10-15 KT WITH SEAS 3-6 FT ALONG THE W COAST OF THE BAJA CALIFORNIA PENINSULA THROUGH THE UPCOMING WEEKEND. NW WINDS AT 15-20 KT...SEAS 3-5 FT...OBSERVED IN THE SOUTHERN GULF OF CALIFORNIA THIS MORNING SHOULD DIMINISH TO 10-15 KT THIS AFTERNOON AND 5-10 KT TONIGHT. GAP WINDS... GULF OF TEHUANTEPEC...N-NE WINDS AT 20-30 KT ARE SURGING THROUGH THE CHIVELA PASS AND IN AND DOWNSTREAM OF THE GULF OF TEHUANTEPEC. MOST GUIDANCE INDICATE THAT THIS NORTHERLY FLOW WILL MAX AT 30 KT WITH THE WINDS DIMINISHING TO 15-20 KT LATE THU. BEST GUESS IS THE NEXT 20-25 KT TEHUANTEPEC EVENT WILL BEGIN LATE MON INCREASING TO A GALE MON NIGHT. GULF OF PAPAGAYO...NE WINDS WILL CONTINUE TO PULSE AT 10-15 KT IN AND DOWNSTREAM OF THE GULF OF PAPAGAYO THROUGH MON THEN INCREASE TO 15-20 KT LATE TUE. $$ NELSON