000 AXPZ20 KNHC 050340 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 0405 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0315 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM 07N78W TO 05N86W TO 07N98W WHERE LOW LEVEL WINDS SUGGEST IT TRANSITIONS TO THE ITCZ TO 07N123W TO 06N133W TO 07N140W. SCATTERED MODERATE CONVECTION EXISTS WITHIN 120 NM N OF THE ITCZ BETWEEN 120W-123W...AND ALSO WITHIN 60 NM S OF THE ITCZ BETWEEN 111W-116W. ...DISCUSSION... ...HIGHLY AMPLIFIED AND PROGRESSIVE FEATURES ACROSS THE REGION... AN ANTICYCLONE MOVING ESE IS CENTERED AT 26N118W WITH A RIDGE EXTENDING NNE TO A CREST OVER THE WESTERN U.S. WITH THE ANTICYCLONE MOVING SE...THIS WILL FOR A SHORTWAVE OVER THE NW PORTION OF THE AREA TO ALSO MOVE E BUT WILL DAMPEN OUT WITHIN THE NEXT 24 HRS. THE FAR SRN END OF A SHORTWAVE TROUGH IS SE OF THE ANTICYCLONE SLIDING EWD ACROSS CENTRAL MEXICO. TO THE SW OF THE ANTICYCLONE...A SHARPENING UPPER LEVEL TROUGH IS EVIDENT ROUGHLY ALONG 127W FROM 09N TO A CUT-OFF LOW AT 20N127W. THE TROUGH EXTENDS SSE FROM THE LOW TO NEAR THE EQUATOR AT 124W. AS THE TROUGH SHARPENS FURTHER WITH TIME THE LOW WILL CONTINUE TO RESPOND BY LIFTING NWD ALLOWING FOR AN AREA OF EXTENSIVE UPPER LEVEL RIDGING TO ITS E AND SE TO EXPAND TO THE N. ANOTHER EXPANSIVE AREA OF UPPER LEVEL RIDGING IS TO THE SW OF THE SHARP TROUGH...AND IS SLOWLY EDGING EWD WITH THE LOW ADVANCING NWD. SATELLITE-DERIVED WINDS INDICATE THAT A SWLY DIFFLUENT PATTERN ALOFT IS PRESENT TO THE E OF THE TROUGH...AND IS HELPING TO SUSTAIN THE AN AREA OF INCREASED MULTILAYERED CLOUDINESS ALONG AND NEAR THE ITCZ AXIS FROM ABOUT 05N-15N AND BETWEEN 116W-126W. THE CONVECTION DESCRIBED ABOVE IN RELATION TO THE ITCZ ABOVE IS EMBEDDED WITHIN THIS AREA OF CLOUDINESS. HIGH LEVEL DEBRIS CLOUDS FROM THE INCREASED AREA OF MULTILAYERED CLOUDINESS ARE STREAMING NNE TO NEAR 20N BETWEEN 117W-125W...AND THEN EWD TO ACROSS CENTRAL MEXICO FROM 17N-24N. ELSEWHERE SATELLITE WATER VAPOR IMAGERY SHOWS MOSTLY MODERATE SUBSIDENCE MAINTAINING A RATHER STABLE ATMOSPHERE WITH DRY AND STABLE CONDITIONS AT THE SURFACE AND LOW LEVELS. AT THE SURFACE...A 1024 MB HIGH CENTER IS ANALYZED AT 28N126W WITH A RIDGE SW TO W OF THE AREA AT 24N140W. PATCHES OF STRATOCUMULUS CLOUDS MOVING WSW WITH ISOLATED SHOWERS ARE SEEN N OF 12N AND W OF 115W. SHORTWAVE TROUGH ENERGY RIDING NE IN THE NRN STREAM BRANCH JUST NW OF THE AREA IS TRIGGERING OFF SCATTERED TSTMS ALONG A WEAKENING FRONT THAT EXTENDS SW TO NEAR 30N140W. THIS ACTIVITY IS RAPIDLY MOVING NEWD FURTHER AWAY FROM THE AREA. OTHERWISE...ONLY MINIMAL DYNAMIC LIFT IS BEING GENERATED BY THE PRESENCE OF THE MONSOON TROUGH AXIS AS STATED ABOVE. WIDELY SCATTERED SHOWERS AND ISOLATED WEAK TSTMS ARE OCCURRING WITHIN 120 NM EITHER SIDE OF THE MONSOON TROUGH AXIS AT THIS TIME. LITTLE OVERALL CHANGES ARE EXPECTED WITH THE PATTERN ALOFT THROUGH THU...THEN ON FRI THE UPPER SHARP TROUGH WILL SLOWLY BEGIN TO DAMPEN OUT AS IT SLIDES E IN RESPONSE TO BROAD RIDGING THAT BUILDS FROM W TO E INTO THE WRN HALF OF THE AREA. IN REFERENCE TO THE MARINE ASPECT OF THE AREA....WINDS AND SEAS REMAIN BELOW ADVISORY CRITERIA WITH THE EXCEPTION OF 8 FT SEAS IN NW SWELL N OF 26N BETWEEN 115W AND 117W OFF THE COAST OF THE BAJA CALIFORNIA PENINSULA. GAP WINDS... A COLD FRONT IS EXPECTED TO MOVE INTO THE GULF OF MEXICO EARLY WEDNESDAY FOLLOWED BY A COOLER AND STABLE AIR MASS. THIS AIR MASS IS FORECAST TO SURGE ALONG THE GULF COAST OF MEXICO...AND THROUGH THE CHIVELA PASS TO EVENTUALLY THE GULF OF TEHUANTEPEC. BASED ON GLOBAL MODEL GUIDANCE...N-NE WINDS OF 20-25 KT ARE FORECAST TO FUNNEL THROUGH THE GULF BEGINNING IN A FEW HRS... THEN GRADUALLY INCREASE TO 30 KT BY EARLY WED EVENING WITH SEAS BUILDING TO A 10 FT MAX LATE TONIGHT AND INTO THU MORNING. WHILE GFS AND ECMWF GUIDANCE SUGGEST WINDS WILL REMAIN BELOW GALE FORCE...THE 18 UTC NAM RUN HINTS AT WINDS REACHING MINIMAL GALE FORCE LATE WED NIGHT AND INTO THU MORNING ENHANCED BY THE MAXIMUM DRAINAGE FLOW OFF THE MEXICAN TERRAIN. WITH LOW CONFIDENCE THINKING OF AN OCCURRENCE OF GALE FORCE WINDS...WILL MAINTAIN STATUS QUO WITH PREVIOUS FORECAST THINKING AND HOLD WINDS AT A MAXIMUM OF 30 KT. MODELS DUE AGREE THAT WINDS THROUGH THE GULF OF TEHUANTEPEC DIMINISH TO LESS THAN 20 KT BY EARLY THU EVENING. WINDS WILL CONTINUE TO PULSE IN THE GULF OF PAPAGAYO TO 20 KT DURING LATE NIGHT AND EARLY MORNING HOURS THEN DIMINISH BELOW 15 KT IN THE AFTERNOON THROUGH FRI. $$ AGUIRRE