000 AXPZ20 KNHC 312143 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Wed Mar 31 2021 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 1800 UTC surface analysis and satellite imagery through 2130 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: Strong high pressure, in the wake of a Gulf of Mexico cold front, will build southward along the eastern slopes of the Sierra Madre Oriental Mountains beginning late today into Thu. The resultant tight gradient between it and lower pressure south of Mexico is expected to result in a surge of strong gale-force winds in the Gulf of Tehuantepec region starting late tonight into early Thu as a cold front quickly moves over the western Gulf of Mexico and across southeastern Mexico. These gale conditions are expected to continue into the upcoming weekend, diminishing to just below gale force on Sun afternoon. Wave heights will build to 10-14 ft Thu and to 12-18 ft Thu night through late Fri, before they begin to slowly subside through Sun. Swell generated by this event will spread well to the southwest and west of the Gulf of Tehuantepec region through the weekend. Mariners navigating through these waters are urge to use caution as these impending conditions are likely to lead to hazardous marine conditions. Please read the latest HIGH SEAS FORECAST- https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for more details. Volcanic Ash Advisory: The Picaya Volcano in southern Guatemala located near 14.4N 90.6W is in a state of unrest and is producing volcanic ash per the Satellite Analysis Branch in Washington, D.C. and also as seen in the latest high resolution GOES-16 satellite imagery. The plume is observed to be spreading out across the offshore waters of Guatemala and extreme southeastern Mexico. While there have been no reports of volcanic ash reaching the surface or reduced visibilities, mariners are still urged to exercise caution and report and observations to the National Hurricane Center by calling 305-229-4425. Please read the latest HIGH SEAS FORECAST- https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for more details on both the Gale Warning and on the Volcanic Ash Advisory. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A trough extends from 09N85W to 05N90W to 04N96W, where latest scatterometer data indicates that it transitions to the ITCZ to 05N107W to 04N115W to 04N122W. It resumes at 04N130W to 03N140W. No significant convection is noted. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features section above for details on an upcoming gap gale-force wind event in the Gulf of Tehuantepec region and on the Picaya Volcano. A relatively weak pressure pattern is over the area north of about 18N. This pattern is supporting gentle to moderate winds throughout the Mexican offshore waters north of 18N. Seas are 3 to 5 ft north of 18N, except 5 to 7 ft in NW swell off Baja California Norte. South of 20N, seas 5 to 7 ft in SW swell. For the forecast, moderate winds across the Gulf of Tehuantepec will abruptly become strong gale force north to northeast winds beginning late tonight into early Thu as a cold front quickly moves over the western Gulf of Mexico and across southeastern Mexico. These gale conditions are expected to continue into the upcoming weekend, diminishing to just below gale force Sun afternoon. Swell generated by this event will spread well to the southwest and west of the Gulf of Tehuantepec region through the weekend. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, and WITHIN 750 NM OF ECUADOR... A Volcanic Ash Advisory is in effect for the Picaya Volcano in southern Guatamela. See Special Features above. Fresh northeast winds are about 200 nm downstream of the Papagayo area, indicating stronger gap winds are likely ongoing closer to shore. Seas are likely up to 8 ft in the plume of gap winds, with a component of longer-period SW swell. Elsewhere light to gentle winds continue over the Central American offshore waters with 3-5 ft wave heights. For the forecast, fresh to strong offshore gap winds will continue across Gulf of Papagayo region through Sun night. Seas will build from northern Costa Rica to Guatemala by Thu, due to seas generated from the Papagayo and Tehuantepec gap wind areas mixing with longer-period SW swell. REMAINDER OF THE AREA... An upper-level low near 26N123W is slowly lifting northeast. Mid to upper-level moisture is present to the east of the low. The earlier related observed moisture along with shower and thunderstorms has pretty much dissipated. Broken to overcast low and mid-level clouds with possible isolated showers are noted from 26N to 32N between 120W-126W. Moderate to fresh trade winds and seas to 8 ft seas are present over the far western part of the area from 05N to 15N west of 131W. SW swell is supporting 5 to 7 ft seas east of 131W, south of 16N. N swell continues to propagating into the waters north of 25N between 120W and 137W leading to seas of 8-9 ft there. This swell will decay by early Thu afternoon allowing for seas to lower to less than 8 ft. For the forecast, winds will diminish west of 131W as high pressure north of the area weakens. Seas to 8 ft will persist over the deep tropics through the latter part of the week with a component of northerly swell west of 120W, and in a mix of SW and NE swell east of 120W. The upper low near 26N123W will dissipate, allowing winds and seas to dissipate Wed. $$ Aguirre