000 AXPZ20 KNHC 112155 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 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 1800 UTC surface analysis and satellite imagery through 2145 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 initially 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 expected to begin late Sat night and continue into Sun morning with seas building to 27 ft near 13.5N96W on Sun night. Winds are not forecast to diminish below gale force through at least Thu morning. INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough extends W from the Pacific coast of Colombia at 06N77W to 07N94W where scatterometer winds indicate a transition to an ITCZ, which continues WNW to 09N125W then dips WSW to beyond 07N140W. Isolated moderate to strong convection is noted within 60 nm either side of a line from 06N81W to 08N86W to 05N93W, within 75 nm of 07N123W, and within 60 nm either side of a line from 09N125W to 10N140W. Scattered moderate isolated strong is observed from 12N to 17N between 129W and 137W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See special features section for information about a gale warning in the Gulf of Tehuantepec that will likely increase to minimal storm strength late Sat night. Moderate northerly winds and 6 to 9 ft seas in long period NW are expected across the Pacific waters W of the Baja Peninsula through Fri evening, then winds will diminish to a gentle variable breeze around a weak trough that develop along 115W. The trough will shift slowly W through the upcoming weekend and dissipate along 119W on Mon. Seas will subside to 4 to 7 ft on Sun night, but quickly build back to 8 to 12 ft N of 24N on Mon in 22 second long-period NW swell. 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 28N 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... Gulfs of Papagayo and Fonseca: Strong NE winds are expected to surge across the Gulf of Papagayo on Sat morning. These strong wind conditions will spread N through the Gulf of Fonseca waters throughout Sat. These NE winds will increase to near gale force in and downstream of the Gulf of Papagayo late Sun night and continue through Mon morning. The resultant area of 7 to 11 ft seas will merge with large seas propagating S from the Gulf of Tehuantepec on Sun. Elsewhere, light to moderate SW winds will persist S of Costa Rica and Panama through Sat with generally between 3 and 5 ft. Fresh N winds are forecast across the Gulf of Panama beginning on Sun morning, and continuing through early Mon morning. REMAINDER OF THE AREA... The pressure gradient between high pres centered near 31N131W and lower pressure across the deep tropics is supporting fresh ENE trades from 09N to 18N between 117W and 140W. Large NW swell in the form of 7 to 10 ft seas is currently observed across the Pacific waters N of 10N W of 110W. These large seas will slowly subside on Fri and Sat. Strong southerly winds will develop across the waters generally N of 29N W of 138W on Sat, in advance of a strong cold front that will reach 32N140W late Sat night. Although the front will stall from near 32N125W to 27N140W on Tue, associated long period NW swell, at 17 to 22 seconds, will propagate SE across the discussion area on Tue and Wed. $$ Nelson