000 AXPZ20 KNHC 181554 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC FRI DEC 18 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1500 UTC. ...SPECIAL FEATURE... A STORM WARNING REMAINS IN EFFECT FOR THE GULF OF TEHUANTEPEC. A COLD FRONT CURRENTLY MOVING ACROSS THE EASTERN BAY OF CAMPECHE IS ALLOWING NORTHERLY WINDS BEHIND THE FRONT TO SPILL THROUGH THE ISTHMUS OF TEHUANTEPEC AND ACROSS THE GULF OF TEHUANTEPEC. MINIMAL GALE FORCE WINDS ARE BELIEVED TO BE CURRENTLY FOUND IN THE GULF OF TEHUANTEPEC. THERE HAVE BEEN NO RECENT SCATTEROMETER DATA IN THE GULF...BUT FIRST VISIBLE IMAGERY OF THE DAY REVEALS A WELL DEFINED ROPE CLOUD MOVING DOWNSTREAM OF THE GULF OF TEHUANTEPEC WHICH LIKELY DELINEATES THE LEADING EDGE OF THE ONGOING GAP WIND EVENT. THIS ROPE CLOUD IS NOW REACHING 13N97W. WINDS ARE FORECAST TO FURTHER INCREASE TO STORM FORCE THIS EVENING AS A 1031 MB HIGH PRES MOVES LATER TODAY INTO SOUTH- CENTRAL TEXAS BEHIND THE COLD FRONT. THIS SYSTEM WILL PRODUCE A VERY STRONG PRES GRADIENT ACROSS THE ISTHMUS OF TEHUANTEPEC FORCING A VERY STRONG AND BROAD GULF OF TEHUANTEPEC GAP WIND EVENT THROUGH THE UPCOMING WEEKEND. WINDS ACROSS TEHUANTEPEC ARE EXPECTED TO REACH STORM FORCE...45-50 KT...BY EARLY THIS EVENING AND LIKELY CONTINUE TO EARLY SAT MORNING WITH THE ASSISTANCE OF THE NOCTURNAL DRAINAGE FLOW. THEN...GALE FORCE WINDS...35 TO 45 FT...ARE FORECAST TO PERSIST THROUGH EARLY SUN. SEAS DOWNSTREAM OF THE GULF OF TEHUANTEPEC WILL BUILD TO 21-22 FT BY THIS EVENING. NE TO E SWELL ASSOCIATED WITH THIS EVENT WILL MERGE WITH LONG PERIOD NW SWELL DRIVING COMBINED SEA HEIGHTS TO 8 FT OR GREATER ACROSS THE EPAC WATERS FROM 07N TO 14N BETWEEN 92W AND 107W ON SAT...AND FROM 03N TO 14N BETWEEN 92W AND 110W ON SUN. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A SURFACE TROUGH EXTENDS FROM THE COAST OF COLOMBIA AT 06N77W TO 03N90W TO 06N100W. THE ITCZ AXIS CONTINUES FROM 06N100W TO 08N106W TO 05N120W TO BEYOND 02N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION CAN BE FOUND FROM 02N TO 06N BETWEEN 80W AND 83W...FROM 02N TO 05N BETWEEN 90W AND 95W...AND S OF 02N BETWEEN 136W AND 132W. ...DISCUSSION... A 1023 MB HIGH PRES IS ANALYZED NEAR 30N129W WITH A RIDGE EXTENDING SE TO NEAR 20N114W. THIS SYSTEM IS FORECAST TO DISSIPATE IN ABOUT 24 HOURS AS A COLD FRONT MOVES ACROSS THE NORTHERN FORECAST WATERS FOLLOWED BY A STRONGER HIGH PRES SYSTEM. UNDER THIS WEATHER PATTERN...THE AREA OF FRESH TO STRONG TRADE WINDS CURRENTLY DOMINATING THE WATERS FROM 08N TO 20N W OF 130W...AND FROM 08N TO 15N BETWEEN 125W AND 130W WILL GRADUALLY SHRINK AND SHIFT SW DURING THE NEXT 24 HOURS...BUT ARE EXPECTED TO INCREASE AGAIN BY SUN COVERING THE WATERS FROM 05N TO 20N W OF 130W...AND FROM 07N TO 17N BETWEEN 117W AND 130W. THE COLD FRONT HAS JUST MOVED INTO THE FORECAST AREA AND WILL REACH FROM 30N132W TO 27N140W THIS EVENING. FRESH TO STRONG NORTHERLY WINDS AND BUILDING SEAS UP TO 13 FT IN NW SWELL ARE EXPECTED IN THE WAKE OF THE FRONT FORECAST TO DISSIPATE BY SUN. A SURFACE TROUGH EXTENDS PARALLEL TO THE COAST FROM NW MEXICO TO NEAR MAZATLAN THEN INTO THE PACIFIC WATERS TO NEAR LAS TRES MARIAS ISLANDS. THE PRES GRADIENT BETWEEN THIS TROUGH AND A 1030 MB HIGH OVER THE GREAT BASIN SUPPORTS FRESH TO 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. SHIP CALL SIGN PHBO LOCATED NEAR THE ENTRANCE OF THE GULF IS REPORTING N WINDS OF 31 KT WHILE AN ALTIMETER PASS INDICATES SEAS OF 7-8 FT FROM 18N TO 23N BETWEEN 108W AND 110W. WINDS AND SEAS WILL DIMINISH LATER TODAY ACROSS THE GULF OF CALIFORNIA LATER TODAY. LOOKING AHEAD...THE ABOVE MENTIONED COLD FRONT WILL MOVE INTO BAJA CALIFORNIA NORTE BY EARLY SUN THEN DISSIPATE. LONG PERIOD NW SWELL AT 20 TO 22 SECONDS CONTINUES TO PROPAGATE SE ACROSS THE FORECAST WATERS REACHING FROM NEAR ACAPULCO MEXICO TO THE EQUATOR THIS MORNING. 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. THIS LONG PERIOD SWELL EVENT WILL MIX WITH SHORTER PERIOD NE SWELL PROPAGATING OUT OF TEHUANTEPEC TO GENERATE AREAS OF CONFUSED SEAS ACROSS THE PACIFIC WATERS AS PREVIOUSLY MENTIONED. MARINE INTERESTS FROM BAJA CALIFORNIA AND NEARBY ISLANDS SOUTHWARD SHOULD REMAIN ALERT FOR THESE HAZARDOUS MARINE CONDITIONS AND ONGOING DANGEROUS SURF CONDITIONS. ADDITIONAL PULSES OF LONG PERIOD NW SWELL ARE EXPECTED BEHIND THE AFOREMENTIONED COLD FRONT. GULF OF PAPAGAYO...NE 15-20 KT DRAINAGE WINDS ARE OBSERVED ACROSS THE GULF OF PAPAGAYO WITH LITTLE CHANGE EXPECTED THROUGH THIS EVENING...THEN THE GRADIENT WILL TIGHTEN SUPPORTING SURGES OF 20-25 KT WITH SEAS BUILDING TO 8 FT ON SAT MORNING. THE GRADIENT SHOULD RELAX THROUGHOUT THE DAY ON SAT WITH 15-20 KT CONDITIONS BRIEFLY ON SAT EVENING BEFORE STRONG NE FLOW RETURNS SAT NIGHT. THIS PATTERN SHOULD REPEAT ON SUN AND MON NIGHTS. $$ GR