000 AXPZ20 KNHC 230341 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC MON DEC 23 2013 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. ...SPECIAL FEATURES... GULF OF TEHUANTEPEC...STRONG HIGH PRES RIDGING BUILDING SWD OVER EASTERN MEXICO BEHIND A WESTERN GULF OF MEXICO COLD FRONT WILL CONTINUE TO BUILD SWD THROUGH TUE TIGHTENING THE PRES GRADIENT OVER SOUTHEASTERN MEXICO. THIS WILL USHER IN A COLD AND DENSE AIR MASS THROUGH THE CHIVELA PASS AND INTO THE GULF. THE INDUCED NLY FLOW WILL RAPIDLY BRING N WINDS OF 20-30 KT THROUGH THE GULF BY EARLY MON MORNING. THESE WINDS WILL RAPIDLY ACCELERATE TO GALE FORCE MON AFTERNOON...REACHING TO 40 KT BY THEN. THE GALE FORCE WINDS THEN QUICKLY ATTAIN STORM INTENSITY ROUGHLY WITHIN 30 NM EITHER SIDE OF A LINE FROM 16N95W TO 14N96W BY LATE MON NIGHT AIDED BY THE ADDED COMPONENT OF NOCTURNAL DRAINAGE FLOW. ELSEWHERE WITHIN 60 NM EITHER SIDE OF A LINE FROM 16N95W TO 14N96W TO 13N97W GALE FORCE WINDS TO 40 KT ARE FORECAST. THE CULPRIT TIGHT PRES GRADIENT IS THEN FORECAST TO WEAKEN JUST ENOUGH ON TUE TO ALLOW FOR THE STORM FORCE WINDS TO DIMINISH TO JUST UNDER STORM STRENGTH...HOWEVER N TO NE GALE WINDS OF 35-45 KT ARE FORECAST WITHIN 30 NM EITHER SIDE OF A LINE FROM 16N95W TO 14N95.5W TO 13N96W AT THAT TIME. THESE WINDS WILL CONTINUE TO FURTHER WEAKEN INTO WED. N TO NE WINDS OF 20-30 KT WITH SEAS OF 10-14 FT ARE FORECAST TO BE WITHIN 90 NM EITHER SIDE OF A LINE FROM 16N95W TO 13N96W TO 11N101W BY TUE EVENING...AND NE TO E WINDS OF 20-30 KT FROM 08N TO 13N BETWEEN 101W-106W WITH SEAS 9- 13 FT BY TUE EVENING. ANOTHER ISSUE FOR THE GULF AND VICINITY WATERS DOWNSTREAM FROM IT WILL BE THAT OF THE RESULTANT SEA STATE. SEAS WILL QUICKLY BUILD TO 10 FT MON AFTERNOON IN THE GULF...AND TO MUCH HIGHER VALUES OF 20 FT BY LATE MON NIGHT INTO TUE. N-NE SWELLS WILL SPREAD S TO SW AWAY FROM THE GULF MON AND TUE REACHING W TO NEAR 105W AND AS FAR S AS POSSIBLY 08N. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH AXIS EXTENDS FROM 06N78W TO 10N87W TO 06N97W TO 06N106W...WHERE LOW LEVEL WINDS SUGGEST IT TRANSITIONS TO THE ITCZ WHICH EXTENDS TO 06N113W TO 08N128W TO BEYOND 06N140W. SCATTERED CONVECTION EXISTS WITHIN 120 NM N OF THE ITCZ W OF 136W. ...DISCUSSION... A LARGE UPPER LEVEL RIDGE EXTENDS FROM NEAR 23N124W NWWD THROUGH 32N128W AND TO A CREST WELL N OF THE DISCUSSION AREA. TO ITS E...THE SRN SEGMENT OF A LARGE UPPER TROUGH OVER THE CENTRAL U.S. EXTENDS SSW ACROSS NRN MEXICO...AND SW FROM THERE INTO THE ERN PORTION OF THE AREA NEAR 14N114W. A JET STREAM BRANCH EXTENDS FROM WELL W OF THE AREA IN THE AREA OF THE TROPICAL CENTRAL PACIFIC ENE THROUGH 17N140W...AND THEN SEWD TO 11N115W...THEN ROUNDING THE BASE OF THE UPPER TROUGH NEWD TO ACROSS CENTRAL MEXICO. A SHORTWAVE TROUGH EMBEDDED IN THE AFOREMENTIONED UPPER TROUGH IS ROUGHLY ALONG A POSITION FROM 15N115W SEWD TO 12N112W TO NEAR 06N106W. OVERCAST TO BROKEN TO MULTILAYERED CLOUDS ARE S OF THE JET STREAM W OF 129W. BROKEN TO SCATTERED MAINLY HIGH LEVEL CLOUDS ARE SEEN FROM 10N TO 17N BETWEEN 118W-129W...AND ALSO WITHIN 450 NM SE OF THE JET STREAM SEGMENT E OF THE SHORTWAVE TROUGH. LATEST SATELLITE IMAGERY SHOWS ENHANCED SCATTERED MODERATE/ISOLATED STRONG CONVECTION E OF THE SHORTWAVE TROUGH FROM 14N TO 16N BETWEEN 105W-107W. THIS ACTIVITY IS MOVING ENE WITH ITS UPPER DEBRIS CLOUDINESS ALREADY SPREADING NEWD TOWARDS CENTRAL MEXICO IN THE SW FLOW AHEAD OF THE UPPER MAIN UPPER TROUGH AXIS. EXPECT SIMILAR ACTIVITY TO CONTINUE THROUGH LATE TUE NIGHT WHILE APPROACHING W CENTRAL MEXICO WITH THE TROUGH FORECAST TO SHIFT EASTWARD TO INLAND MEXICO LATE TUE NIGHT INTO WED. WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS ARE POSSIBLE UNDERNEATH THE AREA OF CLOUDINESS ASSOCIATED WITH THE JET STREAM BRANCH W OF 129W...AND ALSO UNDERNEATH JET STREAM CLOUDINESS E OF THE SHORTWAVE TROUGH OUTSIDE THE AFOREMENTIONED CLUSTERS OF SCATTERED MODERATE CONVECTION. A RATHER ACTIVE UPPER LEVEL TROUGH W OF THE AREA JUST TO THE N OF THE BIG ISLAND OF HAWAII WILL DEEPEN THROUGH LATE TUE NIGHT AS IT APPROACHES THE FAR WESTERN BOUNDARY OF THE AREA. DIVERGENCE ALOFT E OF THE TROUGH IN COMBINATION WITH AN INDUCED TIGHT PRES GRADIENT BETWEEN SURFACE HIGH OVER THE CENTRAL PORTION AS DESCRIBED BELOW WILL GENERATE A SURFACE TROUGH ROUGHLY ALONG 138W S OF 16N BY LATE TONIGHT...AND INTO EARLY MON. MODEL GUIDANCE OF WIND AND MOISTURE INDICATES THAT THIS TROUGH WILL SLOWLY MOVE WWD THROUGH EARLY MON EVENING BEFORE IT PASSES W OF 140W ON TUE. THE TROUGH SHOULD CONTRIBUTE TO MOISTURE AND CLOUDINESS W OF 129W AS MENTIONED EARLIER WITH THE JET STREAM. SATELLITE WATER VAPOR IMAGERY SHOWS VERY DRY AIR COVERING THE AREA TO THE N AND NW OF THE JET STREAM BRANCH DESCRIBED ABOVE IN THE AREA OF THE UPPER TROUGH AND RIDGE. SIMILAR DRY AIR IS NOTED TO THE SE OF THE JET STREAM ASSOCIATED MOISTURE AND CLOUDINESS ...WITH THE EXCEPTION OF SMALL PATCHES OF MOISTURE PRODUCING ISOLATED SHOWERS AND OCCASIONAL WEAK TSTMS ALONG THE MONSOON TROUGH BETWEEN 105W-113W. BROKEN TO SCATTERED STRATOCUMLUS CLOUDS IN THE DRY AND STABLE ATMOSPHERIC CONDITIONS ARE MOVING SSW WITH POSSIBLE ISOLATED SHOWERS N OF 18N E OF 128W...AND MOVING WWD N OF 19N W OF 128W. AT THE SURFACE...NEARLY STATIONARY HIGH PRES OF 1031 MB IS CENTERED N OF THE AREA NEAR 39N132W WITH RIDGE EXTENDING SEWD THROUGH 32N127W AND TO NEAR 22N122W. THE PRES GRADIENT BETWEEN THE RIDGE AND LOWER PRES IN THE VICINITY OF THE ITCZ IS PRODUCING A SMALL POCKET OF FRESH TO STRONG TRADES FROM 11N TO 16N W OF 125W. THE 1031 MB HIGH IS FORECAST TO REMAIN NEARLY STATIONARY OVER THE NEXT 24 HRS WITH SLIGHT WEAKENING AFTERWARDS ALLOWING FOR THE AREA OF FRESH TO STRONG TRADES TO SHRINK IN AREAL COVERAGE. LONG PERIOD NW SWELLS...WITH WAVE PERIODS BETWEEN 18-21 SEC ALONG THE LEADING EDGE HAVE REACHED MUCH OF THE CENTRAL PORTION OF THE AREA. THESE SWELLS WILL CONTINUE TO PROPAGATE SEWD COVERING MUCH OF THE FORECAST AREA TO THE W OF A LINE FROM 19N105W TO THE EQUATOR AT 113W BY MON MORNING...AND TO NEAR 93W BY LATE TUE AT WHICH TIME GUIDANCE ALSO SUGGESTS THAT THE LEADING EDGE OF THE SWELLS WILL CROSS THE EQUATOR TO W OF ABOUT 97W. LATEST WAVEWATCH GUIDANCE SUGGESTS THAT THE LEADING EDGE OF YET ANOTHER SET OF LONG PERIOD SWELLS BEGINS TO PROPAGATE SEWD ACROSS THE FAR NW PORTION OF THE AREA BY EARLY TUE EVENING WITH SEAS TO 8 FT JUST NW OF THE AREA. GULF OF PAPAGAYO...NE-E WINDS OF 20-25 KT ARE AGAIN FORECAST TO BEGIN PULSING BY LATE TONIGHT AS NOCTURNAL DRAINAGE FLOW KICKS IN. THE WINDS ARE FORECAST TO DIMINISH AGAIN DURING MON AFTERNOON...AND MATERIALIZE AGAIN LATE MON NIGHT BEFORE DIMINISHING TO 15-20 KT TUE DURING THE AFTERNOON. GULF OF CALIFORNIA...HIGH PRES WILL BUILD ACROSS THE GREAT BASIN REGION THROUGH MON WHILE INTENSIFYING. THE PRES GRADIENT BETWEEN THE HIGH PRES AND TROUGHING OVER MEXICO WILL STRENGTHEN WINDS OVER THE CENTRAL AND NRN GULF OF CALIFORNIA BY LATE TONIGHT WITH NW FLOW OF 20-25 KT. BY MON EVENING...THESE WINDS ARE FORECAST TO ENCOMPASS JUST ABOUT THE ENTIRE GULF WITH SEAS BUILDING TO AROUND 6 FT. THE PRES GRADIENT THEN RELAXES BY EARLY TUE ALLOWING THESE WINDS TO DIMINISH TO 20 KT OR LESS. $$ AGUIRRE