000 AXPZ20 KNHC 260238 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Tue Mar 26 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 0000 UTC surface analysis and satellite imagery through 0215 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: A strong north to south pressure gradient is developing across southern Mexico tonight as high pressure builds across the western Gulf of Mexico and eastern Mexico. This will support strengthening gap winds funneling through the Chivela Pass with winds likely reaching gale force by late tonight. North to northeast winds are expected to continue pulsing to gale force Tue through Thu with winds nearing strong gale force during the late night and early morning hours. Seas will peak around 18 ft Wed morning, and northeast swell generated by this event will propagate well downstream beyond 100W. Gale conditions will diminish by early Thu afternoon with winds becoming north at mainly fresh speeds over the Gulf of Tehuantepec on Fri and light and then light and variable late on Fri, with seas lowering to below 8 ft as high pressure shifts east-northeast away from the region. 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 specific marine details related to this event. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A trough extends from the coast of Colombia near 06N77W to 05N81W to 06N87W, where scatterometer data from Mon afternoon indicated the ITCZ begins and continues to 03N102W to 02N111W to 02N120W to 03N130W and to beyond 03N140W. Scattered moderate convection is noted within 30 nm of the ITCZ between 127W and 130W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Gulf of Tehuantepec: Please refer to the Special Features section above for details on a Gale Conditions forecast to begin at 12Z Tue. Gulf of California: Relatively tranquil conditions will continue through Thu with winds remaining less than 15 kt and seas generally in the 2-4 ft range. On Fri northwest winds will increase slightly to the moderate to fresh range. The pressure gradient between a 1021 mb high pressure system centered west of Baja California Norte near 27N124W and lower pressure over interior Mexico will maintain moderate to locally fresh northwest to north winds over the offshore waters to the west of the Baja Peninsula through Wed night. Peak seas west of Baja California Sur are at 9 ft. Northwest swell propagating through these waters will gradually decay through midweek as seas subside below 8 ft by Wed. By Thu, a a stronger high pressure system will build towards the region Thu with fresh to strong northwest to north winds expected over the Baja California Norte offshore waters Thu night through Fri night, with seas building to 8-10 ft. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Strong to near gale force northeast to east winds will continue pulsing over the Gulf of Papagayo through Fri night. The strongest winds will occur during the late night and early morning hours as nocturnal drainage flow enhances wind speeds. Seas will build to 10 ft by Wed morning and to 11 ft Thu morning as northeast swell propagates well downstream from the Gulf through Fri night. Gulf of Panama: Moderate to fresh north to northeast winds over the Gulf of Panama will strengthen to fresh to strong speeds late Tue night and persist through late week as high pressure rebuilds over the Caribbean. Seas will build to 8 ft downstream of the Gulf Wed through Fri as cross-equatorial SW swell mixes with the NE wind waves. Southern hemispheric swell will continue to impacting the region between Ecuador and the Galapagos Islands with seas building to 8 ft well offshore by Wed as another set of long-period southwest swell crosses the region. Otherwise, light to moderate winds will remain through this week. REMAINDER OF THE AREA... A cold front over the northwest part of the area extends from near 32N125W to 26N131W and is weakening to near 23N138W, with associated northwest swell, consisting of seas in the 8-12 ft range, impacting the region. Another cold front will move across the northwest waters Tue evening along a position from near 32N125W to 25N132W, and become stationary to 22N136W. This front will introduce another set of long-period northwest swell. This will be followed by yet another cold front that will stall just to the northwest of the forecast area Thu night into Fri, with yet another set of long-period northwest swell that will propagate through the far northwest waters at that time. An enhanced pressure gradient between high pressure centered near 28N125W and the ITCZ is supporting fresh northeast to east trade winds from roughly 06N to 12N west of 120W. Altimeter data from Mon afternoon showed peak seas to 11 ft, likely a combination of long period northwest swell and shorter period northeast wind waves. These trade winds will briefly diminish on Tue and Tue night as high pressure weakens. On Thu, stronger high pressure will build north of 30N on Thu and persist through Fri night. The tightening pressure gradient should support fresh to strong trade winds over a greater coverage than what recently occurred through Fri night west of about 125W. Elsewhere, northwest swell propagating across the high seas domain is maintaining seas of 8 ft or greater over the waters generally north of 01N and west of 104W. The northeast swell generated by gap winds over the Gulfs of Papagayo and Tehuantepec will merge with northwest swell and long period cross-equatorial S to SW swell Tue through Fri night. This will result in a large swath of 8-10 ft seas encompassing an area generally south of 15N and west of 91W to beyond 140W during the late portion of the week. $$ Aguirre