000 AXPZ20 KNHC 180948 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1005 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0945 UTC. ...SPECIAL FEATURE... CURRENTLY 20 TO 25 KT NORTHERLY DRAINAGE WINDS ARE EXPECTED TO QUICKLY INCREASE TO MINIMAL GALE FORCE EARLY TODAY...AND THEN GRADUALLY INCREASE TO MINIMAL STORM FORCE BY LATE TODAY. THE STORM CONDITIONS WILL THEN PERSIST THROUGH SUNRISE ON SAT...THEN STRONG GALE FORCE WILL CONTINUE INTO LATE SAT NIGHT. GALE CONDITIONS WILL END LATE SUN AND THESE NORTHERLY WINDS WILL DIMINISH BELOW 20 KT ON TUE MORNING. MAXIMUM SEAS ARE EXPECTED TO BUILD AS HIGH AS 23 FT DOWNSTREAM OF THE GULF OF TEHUANTEPEC NEAR 13.5N96W EARLY SAT. THE RESULTANT NE SWELL WILL MERGE WITH CROSS EQUATORIAL SWELL...AND LONG PERIOD NW SWELL AS WELL... DRIVING COMBINED SEAS HEIGHTS TO 8 FT OR GREATER ACROSS THE EPAC WATERS FROM 07-15N BETWEEN 92-107W ON SAT. THE NE SWELL WILL PROPAGATE S TO ALONG 04N NEAR 100W ON SAT NIGHT AND REACH THE EQUATOR NEAR 100W ON SUN. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A SURFACE TROUGH EXTENDS SW OFF THE COAST OF COLOMBIA AT 07N78W TO 06N97W WITH SCATTERED MODERATE ISOLATED STRONG CONVECTION OBSERVED WITHIN 90 NM OF A LINE FROM 07N78W TO 03N80W TO 05N96W. SCATTEROMETER WINDS INDICATE THAT AN ITCZ FORMS AT 07N106W TO 03N123W TO 03N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED WITHIN 90 NM OF A LINE FROM 04N109W TO 03N129W AND ALSO WITHIN 90 NM OF 07N117W. ...DISCUSSION... A 1025 MB SUBTROPICAL HIGH IS ANALYZED NEAR 30N132W WITH A RIDGE EXTENDING SE TO NEAR 16N105W. STRONG NE TRADES ARE OBSERVED S OF THE RIDGE...ROUGHLY FROM 10-19N TO THE W OF 122W...WITH SEAS OF 9-12 FT. LONG PERIOD CROSS EQUATORIAL SOUTHERLY SWELL IS MIXING WITH LONG PERIOD NW SWELL...DRIVING COMBINED SEAS TO 8-11 FT ELSEWHERE W OF 108W. THE GRADIENT IS EXPECTED TO SOON RELAX WITH THE NE TRADES BRIEFLY DIMINISHING TO 15-20 KT ACROSS THE TROPICS S OF THE RIDGE AND N OF THE ITCZ. AN INVERTED TROUGH IS MEANDERING OVER/ALONG THE PACIFIC COAST OF MEXICO TO THE N OF 30N. THE GRADIENT IS SUPPORTING NW 20-25 KT WINDS...AND SEAS TO 7 FT...ACROSS THE GULF OF CALIFORNIA FROM 24-29N...WITH NW 15-20 KT CONDITIONS OBSERVED ELSEWHERE IN THE GULF. THE GRADIENT WILL RELAX WITH WINDS DIMINISHING TO 15-20 KT LATE FRI...THEN FURTHER RELAX WITH LIGHT AND VARIABLE WINDS EXPECTED BY LATE SAT. A WEAKENING COLD FRONT WILL MOVE INTO THE NORTHERN GULF OF CALIFORNIA ON SAT NIGHT WITH NORTHERLY 15 KT WINDS DEVELOPING BEHIND THE FRONT. THE GRADIENT WILL TIGHTEN AGAIN THROUGH SUN WITH 15-20 KT NW WINDS EXPECTED ACROSS THE ENTIRE GULF ON SUN NIGHT...EXCEPT 20-25 KT CONDITIONS FORECAST ACROSS THE FAR SOUTHERN GULF OF CALIFORNIA WATERS ON MON. A COLD FRONT WILL MOVE INTO THE FAR NW DISCUSSION WATERS THIS MORNING WITH NORTHERLY WINDS INCREASING BRIEFLY TO 20-25 KT TONIGHT. A NEW BATCH OF LARGE NW SWELL WILL FOLLOW THE FRONT WITH MAX SEAS OF 14 FT REACHING ALONG 32N BETWEEN 130-140W ON SAT. BY THEN THE GRADIENT WILL TIGHTEN AGAIN SUPPORTING STRONG NE TRADES S OF THE RIDGE ACROSS THE TROPICS W OF 125W. THE DISSIPATING FRONT WILL MOVE ACROSS THE NORTHERN BAJA PENINSULA ON SAT WITH THE STRONG NE TRADES EXPANDING E ACROSS THE TROPICS W OF OF 115W. LITTLE CHANGE EXPECTED THROUGH TUE...THEN THE GRADIENT WILL BEGIN TO RELAX ACROSS THE TROPICS S OF THE RIDGE. HOWEVER...THE GRADIENT WILL INCREASE NE OF THE RIDGE WITH STRONG NORTHERLY WINDS EXPECTED TO THE N OF 26N E OF 123W WITH SEAS OF 11-17 FT. 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. $$ NELSON