000 AXPZ20 KNHC 172212 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 2205 UTC THU DEC 17 2015 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 2100 UTC. ...SPECIAL FEATURE... A STORM WARNING REMAINS IN EFFECT FOR THE GULF OF TEHUANTEPEC. A COLD FRONT CURRENTLY MOVING ACROSS THE GULF OF MEXICO IS EXPECTED TO REACH THE CENTRAL BAY OF CAMPECHE EARLY THIS EVENING...AND ALLOW NORTHERLY WINDS BEHIND THE FRONT TO BEGIN TO SPILL THROUGH THE ISTHMUS OF TEHUANTEPEC AND ACROSS THE GULF OF TEHUANTEPEC. WINDS ACROSS THESE PACIFIC WATERS ARE FORECAST TO REACH GALE FORCE LATE TONIGHT INTO EARLY MORNING FRI...AND CONTINUE TO GRADUALLY INCREASE AND EXPAND IN AREAL EXTENT ON FRI. A 1031 MB HIGH PRES CENTER WILL MOVE INTO SOUTH-CENTRAL TEXAS BEHIND THE COLD FRONT ON FRI PRODUCING A VERY STRONG PRES GRADIENT ACROSS THE ISTHMUS OF TEHUANTEPEC AND FORCING A VERY STRONG AND BROAD GULF OF TEHUANTEPEC GAP WIND EVENT FRI THROUGH THE UPCOMING WEEKEND. WINDS ACROSS TEHUANTEPEC ARE EXPECTED TO REACH STORM FORCE...50-55 KT...BY EARLY FRI EVENING AND LIKELY CONTINUE TO EARLY SAT MORNING WITH THE ASSISTANCE OF THE NOCTURNAL DRAINAGE FLOW. THEN...GALE FORCE WINDS ARE FORECAST TO PERSIST THROUGH SUN. SEAS DOWNSTREAM OF THE GULF OF TEHUANTEPEC WILL BUILD TO 21-22 FT BY FRI EVENING. GLOBAL MODELS ALSO SUGGEST THAT THE WIDTH OF THE GALE FORCE WINDS WILL BE UNUSUALLY BROAD FRI EVENING THROUGH EARLY SAT...AND MAY EXTEND EASTWARD ACROSS THE TEHUANTEPEC AREA TO NEAR 93.5W ACROSS THE OFFSHORE WATERS...AND TO PUERTO ARISTA ALONG THE COAST OF MEXICO. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A SURFACE TROUGH EXTENDS FROM 06N85W TO 06N103W TO 05N105W. THE ITCZ AXIS EXTENDS FROM 05N105W TO 05N115W TO 04N125W. NO SIGNIFICANT CONVECTION IS NOTED. ...DISCUSSION... A SURFACE TROUGH EXTENDS PARALLEL TO THE COAST FROM NW MEXICO TO NEAR MAZATLAN...BETWEEN 1029 MB HIGH PRES OVER THE EASTERN PACIFIC AND ANOTHER 1029 MB HIGH PRES CENTERED TO THE NORTH OVER THE GREAT BASIN. THIS HAS TIGHTENED THE PRES GRADIENT ENOUGH TO SUPPORT STRONG NW WINDS ALONG THE LENGTH OF THE GULF OF CALIFORNIA AS WELL AS OFF THE SOUTHERN COAST OF BAJA CALIFORNIA SUR. SEAS ARE REACHING 8 FT IN THE GULF OF THE SUBTROPICAL RIDGE OVER THE EASTERN PACIFIC WILL WEAKEN AHEAD OF AN ADVANCING COLD FRONT THROUGH EARLY FRI. THIS WILL ALLOW THE STRONG WINDS TO GRADUALLY TAPER OFF THROUGH THE NEXT 24 HOURS. LOOKING AHEAD...THE COLD FRONT WILL MOVE INTO BAJA CALIFORNIA NORTE BY EARLY SUN THEN DISSIPATE. LONG PERIOD NW SWELL AT 20 TO 22 SECONDS CONTINUES TO SPREAD SE ACROSS THE FORECAST WATERS MAINLY N OF 20N AND JUST OFF THE BAJA CALIFORNIA PENINSULA. THIS SWELL EVENT WILL COVER THE WATERS FROM CABO CORRIENTES TO NEAR 04N125W BY THIS EVENING...AND REACH FROM NEAR ACAPULCO MEXICO TO THE EQUATOR EARLY FRI. THIS VERY LONG PERIOD SWELL MOVING THROUGH THE FORECAST WATERS WILL GENERATE VERY LARGE AND POWERFUL SURF ACROSS THE REEFS...SHOALS AND COASTAL ZONES OF MEXICO AND CENTRAL AMERICA DURING THE NEXT 48 HOURS. MARINE INTERESTS FROM BAJA CALIFORNIA AND NEARBY ISLANDS SOUTHWARD SHOULD REMAIN ALERT FOR THESE HAZARDOUS MARINE CONDITIONS AND ONGOING DANGEROUS SURF CONDITIONS. THE 1029 MB SUBTROPICAL HIGH OVER THE EASTERN PACIFIC WILL SUPPORT STRONG TRADES THROUGH TODAY FROM 10N TO 21N W OF 125W. THESE TRADE WINDS WILL DIMINISH FRI AS THE HIGH WEAKENS...THEN STRENGTHEN AGAIN BY SAT AS HIGH PRES BUILDS BEHIND THE COLD FRONT. HIGH PRES OVER THE UNITED STATES WILL SUPPORT STRONG GAP WINDS THROUGH THE GULF OF PAPAGAYO LATE FRI AND SAT. $$ CHRISTENSEN