000 AXPZ20 KNHC 171601 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Tue Apr 17 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 1200 UTC surface analysis and satellite imagery through 1500 UTC. ...SPECIAL FEATURES... A gale warning remains in effect for the Gulf of Tehuantepec. Minimal gale force winds of 30-35 kt continue this morning across the Tehuantepec region, extending downwind to near 14.5N95.5W, but are expected to diminish below gale force during the next few hours. Seas to 12 ft will gradually subside to 8-11 ft by early this afternoon. An extensive swath of large N to NE swell generated by this gap wind event will continue to propagate well to the SW of the Tehuantepec area, covering roughly the waters from 03N to 18N between 93W and 110W by early this afternoon. Please refer to the East Pacific High Seas Forecast under AWIPS/WMO headers HSFEP2/FZPN03 KNHC for more details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough extends from 10N71.5W TO 06.5N79W TO 09N84W TO 05.5N90W. The ITCZ stretches from 05.5N90W TO 08N112W TO 07N120W to beyond 08N140W. Scattered moderate to strong convection is from 03.5N to 07N E of 92W to the coast of Colombia. Scattered moderate to strong convection is also noted from 04.5N to 13N between 104W and 140W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A cold front is currently moving across the northern Gulf of California and the northern Baja California peninsula, extends from 31N113W to 26N117W to 23N127W. Strong NNW winds are noted behind the front over the Gulf of California, and behind the front over the offshore waters W of Baja California, particularly N of 28N E of 118W. These winds are forecast to diminish to 20 kt or less by this afternoon. Otherwise, moderate to fresh NW-N winds are forecast across the offshore waters W of Baja California the remainder of the forecast period. Winds are forecast to increase again to 20-25 kt N of Punta Eugenia Thu night and Fri due to a tight pressure gradient between a ridge over the northern forecast waters and lower pressures over the SW CONUS and Mexico. Seas in the 8-10 ft range affecting the offshore waters W of Baja California this morning will begin to gradually subside on Wed, with seas falling to 5-7 ft by late Wed. Gentle to moderate NW winds are expected to prevail across the Gulf of California Wed through Fri. Gulf of Tehuantepec: Please, see Special Features section above for details. Currently, marine guidance suggests that another gap wind event, with minimal gale force winds, could occur across the Gulf of Tehuantepec by late Thu as a strong high pressure builds southward across the Central Plains of U.S. and the Gulf of Mexico. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Pulsing fresh to strong NE-E winds are expected across and downstream of the Gulf of Papagayo during the late afternoon through early morning hours each day through Fri. Gulf of Fonseca: An overnight scatterometer pass indicated northerly winds of 20-25 kt across the Gulf of Fonseca and downwind to near 12N. These winds are occuring behind a dissipating frontal boundary over the NW Caribbean Sea extending SW into central Honduras. Winds will remain fresh and gradually diminish to 15-20 kt this afternoon. Gulf of Panama: A couple of ship observations also indicate fresh to strong northerly winds across the Gulf of Panama. Fresh northerly winds are expected across the Gulf of Panama through Wed night, with seas of 4-6 ft. Elsewhere, light to gentle winds are expected through the forecast period, with a weak surface through extending along 08- 09N yielding light S to SW winds to its south. Seas in the 3 to 5 ft range will continue over most of the area. Cross equatorial SW swell will mix with residual swell from Papgayo tonight through Fri and raise seas to 5-7 ft S of 10N. REMAINDER OF THE AREA... As previously mentioned, a cold front is moving SE across the northern Baja California peninsula and extends from 31N113W to 26N117W to 23N127W. The front will become ill defined across the NE waters today. A 1029 mb high pressure located near 35N133W follows the front, and extends a ridge across the northern forecast waters, including the entrance of the Gulf of California and Las Tres Marias islands. This system will weaken some over the next 24-48 hours, and then will be reinforcing by a stronger high pressure by late Thu. Large NW swell continues to propagate southeastward through the forecast waters, with max seas of around 11 ft based on altimeter data. This swell is mixing with waves generating in the Tehuantepec area. As a result, seas of 8 ft or greater will cover most of the area W of 108W today. Cross equatorial SW swell has moved into the southern forecast waters this morning. Marine guidance suggests that seas of 8-10 ft will dominate the waters S of 04N between 97W and 120W by early this evening. Seas are forecast to subside to 8 ft or less across most of the area W of 120W by late Wed. At that time, seas of 8-10 ft are expected mainly S of 10N between 92W and 120W. $$ Stripling