000 AXPZ20 KNHC 041537 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1300 UTC Mon Mar 4 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... Open East Pacific Waters Gale Warning: A frontal trough has reached the NW corner of the forecast area followed by a cold front that is currently approaching 30N140W. Fresh to strong winds are ahead of the trough, and between the trough and the cold front mainly due to the proximity of the associated low pressure system. Seas to 9 ft are already affecting the waters N of 27N W of 137W. The cold front will move into the area later today ushering in strong to near gale force winds N of 27N, with frequent gusts to gale force likely. A new set of large NW swell of 16 ft will also accompany the front, forecast to reach a position from 30N128W to 21N136W by early Tue morning, and from 30N122W to 22N130W by early Wed morning. Winds will diminish below gale force by Tue afternoon, then to fresh levels Tue night, while the swell train will continue to propagate SE across the forecast region, with seas of 8 ft or greater dominating the waters W of a line from 30N124W to 20N130W to 13N140W by Wed morning. Then, seas will gradually subside to less than 8 ft by late Thu. Gulf of Tehuantepec Gale Warning: A strong ridge building E of the Sierra Madre Oriental in Mexico will support the next gap wind event in the Gulf of Tehunatepec beginning tonight. Strong winds will begin to funnel through the Chivela Pass tonight, reaching minimal gale force by Tue morning, and peaking at 40 kt Tue evening through early Wed morning. Gale force winds will then continue into early Thu, with fresh to strong winds thereafter through early Fri. Seas will peak around 16 ft during the strongest winds. Please read the latest High Seas Forecast issued by the National Hurricane Center under AWIPS/WMO headers FZPN03 KNHC/HSFEP2 or at website https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for further details about these gale warnings. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A trough axis extends from 07N82W to 06N88W. The Intertropical Convergence Zone axis continues from 06N88W to 01N110W to 03N125W to 05N140W. Scattered moderate to isolated strong convection is from 03N to 06N between 126W and 131W. Similar convection is also noted near 06N133W. As it is normal for this time of the year, a second and pretty active ITCZ is analyzed S of the Equator. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Gulf of Tehuantepec: A Gale Warning is in effect for the Gulf of Tehuantepec. Please read the Special Features section for details. A ridge will dominate the offshore waters W of Baja California through Wed. The pressure gradient has tightened between the ridge W of Baja California and lower pressures over mainland Mexico, resulting in fresh to strong winds offshore of Baja California, particularly N of 23N E of 116W. A pair of ship observations confirmed the presence of these winds, forecast to diminish to 20 kt or less by tonight. On Thu, a weakening cold front will reach Baja California Norte with minimal impacts. No large long-period swell is anticipated to affect the region. Gulf of California: Generally benign marine conditions are expected across the Gulf of California through most the forecast period, with the exception of the northern Gulf where fresh to locally strong winds are expected Wed through Fri night. These winds will be associated with the passage of a weakening cold front and a pre-frontal trough. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Fonseca: Fairly tranquil marine conditions will persist through early Tue night. Winds will increase to fresh to strong late Tue night through early Fri as the pressure gradient across the region tightens. Gulf of Papagayo: Fresh to strong winds are expected through Tue, but mainly at night with the assistance of the drainage flow. An increase in the Caribbean pressure gradient will significantly boost winds Tue night through Fri night, when strong to near gale force winds are expected. Seas are forecast to peak around 10 to 12 ft during the strongest winds. Gulf of Panama: Moderate to fresh winds will prevail through Tue. A tightening pressure gradient from high pressure building to the north will bring fresh to strong N winds Tue night through at Fri night. Seas will build to around 9 ft Thu morning, then to around 10 ft Fri morning. Elsewhere, NE swells generated by the gap wind events in the Gulfs of Tehuantepec and Papagayo will spread SW and then W reaching roughly the waters from 03N to 14N between 86W and 110W. NE swells generated by the Gulf of Panama winds will spread SW towards the Galapagos Islands by the end of the week. REMAINDER OF THE AREA... Marine conditions are beginning to deteriorate N of 26N W of 130W as a low pressure system and associated frontal boundaries affect this region. Please see the Special Features Section for more details on a developing gale warning. Elsewhere, long-period NW swell mixing with tradewind flow is maintaining an area of 7 to 9 ft seas from 06N to 12N W of 127W. These seas will gradually subside to less than 8 ft by early Tue. Later in the week, another combination of mixed NW swell and wind waves are expected to support seas of 7 to 9 ft roughly across the same area. $$ GR