000 AXPZ20 KNHC 130339 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 339 UTC Fri Jan 13 2017 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 0000 UTC surface analysis and satellite imagery through 0300 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec gale warning: A brief tranquil period during the past several hours is ending with winds in the Gulf of Tehuantepec in the process of increasing to fresh to strong as the local pressure gradient tightens. The winds will increase to near gale force after midnight with the added assistance of nocturnal drainage flow, then will reach minimal gale force by Friday evening. Gale force winds may then briefly diminish during the afternoon hours Saturday before returning again Saturday night into early Sunday before diminishing below gale force. Northerly winds will then be fresh to strong into early Monday before diminishing and shifting to the south-southwest through the early part of next week. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 05N76W to low pressure near 05N80W to 03N98W. The intertropical convergence zone axis extends from 03N98W to 06N120W to 08N135W to 07N140W. Scattered moderate convection is from 04N to 11N between 107W and 118W, within 120 nm north of the axis between 122W and 130W, and also within 210 nm north of the axis west of 130W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the special features section for information on the Gulf of Tehuantepec gale warning. Elsewhere, moderate northwest to north winds prevail over the waters adjacent to the Baja California peninsula, and winds will shift to the southwest ahead of an approaching trough, which is the remnants of a cold front. Seas are in the 4 to 6 ft but will build to 5 to 8 ft west of Baja California Norte behind the trough by Friday night. High pressure will build in the wake of the trough this weekend while low pressure troughing sets up across southern California. This will increase the pressure gradient offshore of southern California generating fresh northerly swell which will propagate back into the waters offshore of Baja California Norte Sunday night through Monday, then will decay thereafter once the gradient slackens. In the Gulf of California, mainly light and variable winds and seas of 2 ft or less will prevail south of 30N, with moderate to fresh south-southwest winds north of 30N east of a trough which extends from southwest Arizona to near 30N115W, where seas are also 2 to 4 ft. Little change is anticipated across the Gulf of California through the upcoming weekend and early next week, except on Saturday night when winds will increase to fresh in the southern portion as the trough mentioned above moves through. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... In the Gulf of Papagayo, fresh to strong northeast flow will continue to pulse through early next week, approaching near gale force by Saturday morning. Seas will build to 8 to 9 ft during the strongest winds. Winds will also pulse to fresh to strong across the offshore Gulf of Fonseca waters by early Friday, diminishing thereafter. In the Gulf of Panama and near the Azuero Peninsula, fresh northerly winds will increase to fresh to strong in the next few hours, then will diminish to moderate to fresh Friday morning through early next week. REMAINDER OF THE AREA... A surface trough is passing through the northern waters from 30N119W to 17N126W. Associated winds are 20 kt or less, however a set of accompanying northwest swell with seas of 8 to 11 ft continues to move in behind it. High pressure ridging is building in the wake of the trough supporting moderate to fresh trades to the southwest of the ridging across the west-central waters. Combined seas are 8 to 10 ft north of the ITCZ west of 120W in mixed northeast and northwest swell. The high pressure ridging will gradually strengthen this weekend through early next week, increasing trades to fresh to strong while expanding the stronger trades in coverage. Seas will also build up to 11 ft as a result of the increasing and expanding trades. $$ LEWITSKY