000 AXPZ20 KNHC 171004 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1005 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0930 UTC. ...SPECIAL FEATURE... A STORM WARNING IS NOW IN EFFECT FOR THE GULF OF TEHUANTEPEC. A COLD FRONT CURRENTLY EXTENDING FROM SE LOUISIANA TO THE FAR WESTERN BAY OF CAMPECHE IS FORECAST 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 WILL QUICKLY REACH GALE FORCE AFTER MIDNIGHT TONIGHT...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...FRI AFTERNOON AND FRI NIGHT BEFORE DIMINISHING SLIGHTLY TO THE 40-45 KT RANGE OVERNIGHT FRI THROUGH SUN. SEAS DOWNSTREAM OF THE GULF OF TEHUANTEPEC WILL BUILD TO 22 FT BY FRI EVENING. GLOBAL MODELS ALSO SUGGEST THAT THE WIDTH OF THE GALE FORCE WINDS FRI THROUGH EARLY SAT WILL BE UNUSUALLY BROAD...AND MAY EXTEND EASTWARD ACROSS THE TEHUANTEPEC AREA TO NEAR 93.5W ACROSS THE OFFSHORE WATERS...AND TO PUERTO ARISTA ALONG THE COAST. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A SURFACE TROUGH EXTENDS FROM 09N82.5W TO 07.5N92W TO 08N98W TO07N101W. THE ITCZ EXTENDS FROM 05N110W TO 03N118W TO 04N130W. WIDELYSCATTERED MODERATE ISOLATED STRONG CONVECTION NOTED FROM 05NTO 11N W OF 109W. ...DISCUSSION... A 1030 MB HIGH PRES LOCATED N OF AREA NEAR 33N134W IS SHIFTING SLOWLY SOUTHEASTWARD AND BECOMING MORE E-W ORIENTED EARLY THIS MORNING. THE ASSOCIATED RIDGE EXTENDS ACROSS THE N WATERS TO NEAR 20N111W. THE PRESSURE GRADIENT BETWEEN THE HIGH AND LOWER PRESSURES IN THE VICINITY OF THE ITCZ MAINTAINS A BROAD AREA OF 20-25 KT TRADE WINDS IN AN AREA GENERALLY W OF 120W AND N OF THE ITCZ TO 26N. LARGE NW SWELL CONTINUES TO MOVE THROUGH THE FORECAST REGION AND IS MIXING WITH NE WIND WINDS IN THIS TRADE WIND ZONE TO PRODUCE SEAS OF GENERALLY 10 TO 13 FT PER RECENT ALTIMETER DATA. THE LONG PERIOD NW SWELL IS ALSO PRODUCING SEAS TO 8 TO 11 FT ACROSS THE REMAINDER OF THE FORECAST WATERS N OF 04N AND W OF 110W. THIS AREA OF FRESH TO STRONG TRADE WINDS WILL GRADUALLY SHRINK AND SHIFT SW OVER THE NEXT FEW DAYS AS THE HIGH PRES MOVES SE AND GRADUALLY WEAKENS. A COLD FRONT IS FORECAST TO MOVE INTO THE AREA EARLY FRI AND EXTEND FROM 30N133W TO 27N140W BY FRI EVENING...AND FROM 30N126W TO 25N140W EARLY SAT. BUILDING HIGH PRES IS EXPECTED IN THE WAKE OF THE FRONT...WITH ANOTHER MODEST PULSE OF NW SWELL BEGINNING TO MOVE THROUGH THE AREA. THE PRESSURE GRADIENT BETWEEN HIGH PRESSURE OVER THE GREAT BASIN AND A DEVELOPING SURFACE TROUGH ALONG THE COAST OF MEXICO HAS RESULTED IN NW WINDS OF 20 TO 25 KT SPREADING THROUGH THE FULL LENGTH OF THE GULF OF CALIFORNIA PER RECENT RAPIDSCAT DATA...WITH NE WINDS 15-20 KT BLOWING ACROSS THE BAJA PENINSULA AND ACCELERATING THROUGH THE LARGER GAPS TO PRODUCE AREAS OF 20 KT NE WINDS WITH HIGHER GUSTS ACROSS THE PACIFIC COASTAL WATERS S OF PUNTA EUGENIA. SEAS INSIDE THE GULF HAVE BUILT 6-8 FT EARLY THIS MORNING...AND WITH THESE WINDS EXPECTED TO PERSIST THROUGH FRI MORNING...SEAS WILL BUILD 7-10 FT. WINDS AND SEAS WILL BEGIN TO DIMINISH FRI AFTERNOON AND FALL BELOW 20 KT AND SEAS LESS THAN 8 FT LATE FRI. ANOTHER PULSE OF LONG PERIOD NW SWELL AT 20 TO 22 SECONDS IS CURRENTLY MOVING INTO THE FORECAST AREA N OF 20N TO THE FAR NW PORTION OF BAJA CALIFORNIA. THIS SWELL EVENT WILL SPREAD SE COVERING THE WATERS N OF 20N W OF CENTRAL BAJA CALIFORNIA TONIGHT...AND FROM CABO CORRIENTES TO NEAR 04N125W BY LATE TODAY AND REACH FROM 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. $$ STRIPLING