000 AXPZ20 KNHC 251515 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1515 UTC Mon Mar 25 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: A strong north to south pressure gradient is expected to develop 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. N to NE 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 NE swell generated by this event will propagate well downstream beyond 100W. Gales will diminish Thu morning with winds becoming light and variable over the Gulf of Tehuantepec by Fri as high pressure moves 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 05N86W. The ITCZ continues from 05N86W to 04N100W to 02N115W to 03N125W to beyond 04.5N140W. Scattered moderate convection is noted within 60 nm north of the ITCZ between 90W and 92W, and within 90 nm south of the ITCZ west of 130W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Gulf of Tehuantepec: Please refer to the Special Features section above for more information on the Gale Warning currently in effect. Gulf of California: Relatively tranquil conditions will prevail through late week with winds remaining less than 15 kt and seas generally in the 2-4 ft range. The pressure gradient between 1021 mb high pressure centered west of Baja California Norte near 29N122W and lower pressure over interior Mexico will maintain moderate to locally fresh NW to N winds over the offshore waters W of the Baja Peninsula through Wed night. Peak seas were analyzed to 10 ft this morning off Baja California Sur based on recent altimeter data. NW swell across the region will gradually decay through midweek as seas subside below 8 ft by Wed. Looking ahead, a stronger high pressure system will build towards the region Thu with fresh to strong NW to N winds expected over the Baja California Norte offshore waters Thu night through Fri night. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Strong to near gale force NE to E 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 as NE swell propagates well downstream from the Gulf through Fri night. Gulf of Panama: Winds over the Gulf of Panama have likely diminished to moderate to fresh speeds. N to NE winds 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 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 SW swell crosses the region. Otherwise, light to moderate winds will prevail this week. REMAINDER OF THE AREA... A cold front extends across the far NW waters from 30N131W to 25N140W with associated NW swell impacting the region. Another cold front will enter the far NW waters Tue night and introduce a reinforcing set of long period NW swell. This will be followed by yet another cold front that will stall just NW of the forecast area Thu night into Fri, bringing another round of long period NW swell by late week. An enhanced pressure gradient between high pressure near 29N122W and the ITCZ is supporting fresh NE to E trade winds from roughly 06N to 12N west of 120W. Recent altimeter data showed peak seas within this area reached 12 ft, likely a combination of long period NW swell and shorter period NE wind waves. These trade winds will gradually diminish through midweek as high pressure weakens. Looking ahead, 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 through late week generally west of 125W. Elsewhere, NW 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 110W. The NE swell generated by gap winds over the Gulfs of Papagayo and Tehuantepec will merge with NW 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 90W to beyond 140W during the late week. $$ Reinhart