000 AXPZ20 KNHC 111603 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Thu Jan 11 2018 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 1545 UTC. ...SPECIAL FEATURE... Gulf of Tehuantepec Gale Warning: Post frontal high pressure across the western Gulf of Mexico will surge into the Gulf of Tehuantpec at minimal 30-35 kt gale force just after sunrise on Fri, and quickly increase to 35-45 kt strong gale conditions on Fri afternoon. Seas are forecast to build to a maximum of 24 ft downstream of the gulf waters near 14N95.5W on Fri night. Minimal storm force winds are possible on Sun morning with seas building to 29 ft near 13.5N96W. Winds are not forecast to diminish below gale force through next Thu morning. INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough extends W across the Gulf of Panama from 08.5N78W to 08N86W, then dips SW to 06N100W where scatterometer winds indicate a transition to an ITCZ, which continues W through an embedded 1012 mb surface low pressure at 07N125W to beyond 07N140W. Isolated moderate to strong convection is noted within 150 nm either side of a line from 07.5N83W to 05N93W, within 90 nm either side of a line from 06N97W to 07N107W, and within 90 nm of 07N123W. Scattered moderate isolated strong is observed from 12N to 18N between 130W and 138W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See special features section for information about a gale warning in the Gulf of Tehuantepec that may be upgraded to a storm warning on Sun. Moderate to locally fresh northerly winds and 6 to 9 ft seas are expected across the Pacific waters W of the Baja Peninsula through Fri morning, then winds will diminish to a gentle and variable breeze around a weak trough that develop along 115W. the trough will shift slowly W through the upcoming weekend as seas subside to 4 to 7 ft. Gulf of California: Moderate to fresh NW flow expected across the northern and southern gulf waters, with fresh to strong NW winds forecast across the gulf waters from 24N to 27N through Fri afternoon, with seas building to 8 ft in the long fetch areas. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: A weak pressure gradient over central America is maintaining moderate to fresh gap winds over the Gulf of Papagayo. Strong winds are expected to develop on Sat morning as high pressure builds over the W Caribbean. Winds could reach near gale force late sun night into Mon afternoon. The area of seas developing S of the Gulf of Papagayo will merge with the larger area of seas propagating S from the Gulf of Tehuantepec on Sun. Gulf of Fonseca...Fresh to strong NW to N winds forecast to begin around sunset on Sun. Elsewhere, light to moderate SW winds will persist S of Costa Rica and Panama. Seas will remain generally between 3 and 5 ft. N winds over the Gulf of Panama could become fresh by Mon morning. REMAINDER OF THE AREA... The pressure gradient between high pres centered near 31N132W and lower pressure in the vicinity of the ITCZ will support fresh trade winds from 15N to 18N between 122W and 137W today. The areal coverage of seas 8 ft or greater will peak today, encompassing waters W of 110W and N of 10N. This large area of high seas will slowly decay Fri and Sat. A cold front reaching the NW part of the discussion area Sun will generate large long period NW swell, and building seas to as high as 21 ft in far northwest waters near 30N140W by Sun evening. $$ Nelson