000 AXPZ20 KNHC 120947 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Fri Jan 12 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 0600 UTC surface analysis and satellite imagery through 0845 UTC. ...SPECIAL FEATURE... Gulf of Tehuantepec Gale Warning: Post frontal high pressure across NE Mexico and the western Gulf of Mexico will surge across the Gulf of Tehuantpec initially at minimal 25-35 kt gale force just after sunrise this morning, and quickly increase to 35-45 kt strong gale conditions by late this afternoon. Seas are forecast to build to a maximum of near 20 ft downstream of the gulf waters near 14N95.5W this evening. Strong gales will continue through Sat and then increase to minimal storm force winds Sat night and continue through sunrise Sun morning, with seas forecast to build to 23 ft near 13.5N96W by sunrise Sun. This gale event will be long-lived, with winds 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 06N77.5W TO 09.5N86W TO 08N101W, where overnight scatterometer winds indicate a transition to an ITCZ, which continues W to 06.5N116W TO beyond 09N140W. Widely scattered moderate isolated strong convection is noted from 05N to 07.5N between 86W and 101W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Moderate to locally fresh northerly winds and 6 to 9 ft seas in long period NW swell are expected across the Pacific waters W of the Baja Peninsula through this evening, before winds will begin to diminish to a gentle variable breeze around a weak trough that develops along 114W-115W. The trough will shift slowly W through the upcoming weekend and dissipate along 119W by early 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 very long period NW swell of 18-22 seconds. Gulf of California: Moderate to fresh NW winds across the gulf waters have increased to strong through central portions tonight from 24N to 28.5N, and are expected to increase slightly to 20- 30 kt through sunrise between 24.5N AND 28.5N. Winds are then expected to diminish very slowly through late tonight. Seas of 5 to 8 ft will peak at 6-9 ft before sunrise and then subside slowly through Sat morning. See special features section for information about a gale warning in the Gulf of Tehuantepec that will likely increase from gale to minimal storm strength Sat night. 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, as strong high pressure builds across the Gulf of Mexico and much of Central America, behind a cold front moving southward through the Western Caribbean. These strong gap wind conditions will expand N and across the Gulf of Fonseca waters throughout Sat. NE winds will increase to near gale force in and downstream of the Gulf of Papagayo late Sun through 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 Sat evening, and continuing through early Mon morning. REMAINDER OF THE AREA... The pressure gradient between high pres centered near 35N128W and lower pressure across the deep tropics is supporting fresh ENE trades from 09N to 20N between 117W and 140W. Moderate to large NW swell producing seas of 7 to 9 ft is currently observed across the Pacific waters N of 10N W of 110W. These seas will slowly subside on today through 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 generated behind the front, at 17 to 22 seconds, will propagate SE across the discussion area on Tue and Wed. This large swell will merge with NE swell propagating away from the Tehuantepec region to produce large and confused seas to the S of 15n between 105W and 120W on Tue and Wed. $$ Stripling