000 AXPZ20 KNHC 071603 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1308 UTC Mon Jan 7 2019 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... Gulf of Tehuantepec Gale Warning: Fresh to strong gap winds in the Gulf of Tehuantepec will decrease to less than 20 knots this afternoon. The wind speeds will increase again to near gale force tonight, as high pressure builds across the eastern slopes of the Sierra Madre montains in Mexico. Then, winds will further increase to gale force across the Gulf waters on Tuesday night, as strong high pressure expands eastward across the entire Gulf of Mexico. Gale conditions will prevail through Thursday night, with the wind speeds decreasing to less than gale-force on Friday. Currently, marine guidance suggests winds in the 30 to 40 kt range, and seas building up to 14 or 15 ft Wed through Thu. Please see the latest High Seas Forecast product under AWIPS/WMO headers HSFEP2/FZPN03 KNHC for more details. Cold front Gale Warning: A strong cold front is forecast to reach the NW corner of the forecast area early this afternoon. Strong to minimal gale force SW winds are expected ahead of the front, particularly N of 29N W of 137W. A new set of long period NW swell will follow the front, with seas quickly building up to 14-15 ft. Gale conditions will persist just ahead of the front through tonight. Strong to near gale force W to NW winds are also expected in the wake of the front, forecast to reach a position from 30N134W to 25N140W tonight, and from 30N132W to 24N140W early Tue morning. The new swell event will propagate across the forecast waters, with seas building up to 26 or 27 ft behind the front, and along 30N by Tue afternoon. Please see the latest High Seas Forecast product under AWIPS/WMO headers HSFEP2/FZPN03 KNHC for more details. .INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough extends from the coast of Colombia near 06N77W to 07N85W to 05N94W. The ITCZ continues from 05N94W to 06N110W to 05N125W to beyond 04N140W. No significant convection. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A ridge dominates the offshore forecast waters W of Baja California peninsula, producing mainly gentle to moderate northerly winds. The ridge will persist across the area through at least Wed. Seas of 8 to 10 ft in NW swell are noted across these waters based on altimeter data. A strong cold front moving across the open waters that are to the west of Baja California, today and Tue will bring a new set of long period NW swell on Wednesday morning, with sea heights ranging from 8 feet to 16 feet. This swell will spread SE across the offshore waters of Baja California through Friday. Moderate NE winds will dominate the region with this second swell event. Gulf of California: NW winds of 15 to 20 kt are expected over the southern Gulf early this afternoon as the pressure gradient tightens over north-central Mexico. By Tue, moderate to fresh NW winds will affect most of the Gulf of California waters. Winds will become light and variable again over the northern Gulf by Tue night. However, moderate to fresh NW winds are forecast to persist across the central and southern Gulf through Thu. Gulf of Tehuantepec: Please, see Special Features section for details. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Fresh to strong NE to E winds are expected across and downstream of the Gulf of Papagayo through Friday. The wind speeds will be the greatest during the overnight and early morning hours with the assistance of the nocturnal drainage flow, and some added enhancement from the easterly gradient flow from the SW Caribbean Sea. Gulf of Panama: mainly light and variable winds are forecast to Wed night with seas generally in the 3 to 5 ft range. Winds are expected to increase to 10-15 kt Thu and Thu night, with seas of 4-6 ft. REMAINDER OF THE AREA... A 1024 mb high pressure is centered near 29N120W, and extends a ridge across the northern forecast waters. A weak trough extends from 21N116W to 14N118W. Latest scatterometer data indicated fresh to strong NE winds on the west side of the trough axis, and mainly from 17N to 22N between 116W and 125W due to the pressure gradient between the high pressure and the trough. The high pressure center will remain nearly stationary while weakening as a strong cold front moves eastward across the norther forecast waters. The trough will dissipate and the associated winds will diminish to 20 kt or less by late today. Looking ahead, another strong cold front is forecast to reach the NW corner of the area on Thu, followed by another set of long period NW swell. Marine guidance suggests again strong to minimal gale force SW winds ahead of the front with strong to near gale force winds in the wake of the front. $$ GR