000 AXPZ20 KNHC 151527 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1327 UTC Wed Nov 15 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 1200 UTC surface analysis and satellite imagery through 1500 UTC. ...SPECIAL FEATURES... Strong to minimal gale force northerly winds will persist across the Gulf of Tehuantepec through early this afternoon. The ridge north of the area will weaken slightly today, allowing for winds to disminish below gale force. Model guidance suggests that northerly winds in the 20 to 30 kt range will continue to blow across the Tehuantepec region through Sat, but mainly during the overnight and early morning hours with the assistance of the nocturnal drainage flow. Winds are forecast to increase again to gale force on Sun as a strong cold front moves into the western Gulf of Mexico. Computer model indicates winds of 30-35 kt and building seas of 12-13 ft by Sun night. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A monsoon trough extends from 10N85W to 08N100W to 09N112W to 07N130W then transitions to the Intertropical Convergence Zone extending to 07N140W. Scattered moderate convection can be found north of 06N between 78W and 84W, from 07N to 09N between 90W and 109W, and from 07N to 11N between 109W to 122W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please refer to the Special Features section for information regarding the ongoing Gulf of Tehuantepec gale warning. A 1019 mb high pressure located near 31N125W extends a ridge across the offshore waters of Baja California supporting gentle to moderate northerly winds and 5 to 7 ft seas, with the help of residual northwesterly swell. The high pressure will move closer to the offshore forecast waters in about 24 hours allowing winds to slightly diminish through Fri. Winds will increase again to 15-20 kt off Baja California Norte by late Fri as a stronger ridge builds north of the area, then shifts eastward through Sun allowing the winds to diminish again. Light northwest winds will persist across the Gulf of California through Fri in a weak pressure pattern. A cold front will move across Baja California Norte and northern Gulf of California late Fri and Sat. Strong high pressure building behind the front N of the area over the Great Basin will bring strong NW winds in the northern Gulf of California Sat, reaching the central and southern parts late Sat into Sun. Expect building seas of 6-7 ft S of 28N with these winds, forecast to diminish to 20 kt or less by late Sun as the front dissipates and the high pressure north of the area shifts east. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Fresh to locally strong southwest to west winds and seas of 8-9 ft are forecast to persist south of Panama, including also the Gulf of Panama through Thu. The winds and seas are the result of a tight pressure gradient related to 1007 mb low pressure located over the southwest Caribbean. Winds and seas will diminish by late Thu as the low pressure weakens and starts drifting farther north. Elsewhere, gentle to moderate winds and seas of 4 to 6 ft are expected N of the monsoon trough, which will fluctuate between 08N and 10N, with moderate to locally fresh S to SW winds and seas of 5 to 7 ft S of the monsoon trough through the remainder of the work week. REMAINDER OF THE AREA... A 1012 mb low pressure area centered near 21N134W has a small area of 8 ft seas N of the low center, covering the waters from 21N to 25N between 131W and 135W. A swirl of low clouds is associated with this low. A passing short wave trough and dry air aloft is expected to cause the low to weaken into a trough during the next 24 hours. At that time, winds will be less than 20 kt with seas less than 8 ft. A 1011 mb low pressure is near 30N140W. The low will move ENE over the next 24 hours allowing the associated cold front to enter the discussion area later today. Fresh to strong northerly winds and seas of 8 to 11 ft in NW swell will follow the front, forecast to reach a position from 30N137W to 23N140W tonight, and from 30N134W to 24N140W by early Thu morning. Seas of 8 ft or greater will continue to propagate across the NW waters on Fri, particularly NW of a line from 30N130W to 22N140W. $$ GR