000 AXPZ20 KNHC 110153 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 135 UTC Mon May 11 2020 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 0300 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: High pressure building across the eastern slopes of the Sierra Madre Mountains in Mexico will promote a late season Gulf of Tehuantepec event. Fresh to strong northerly gap winds are already blowing across the Tehuantepec region, and will increase to minimal gale force late tonight through Mon morning. Winds will diminish below gale force by early Mon afternoon with fresh to near gale force winds continuing through Tue morning. Peak seas with this gale event will build to 13 to 14 ft by early Mon morning. Climatologically, the final gale-force event occurs in late March or early April. Only a couple of Tehunatepec events have been detected in May since the 1999-2000 season, one in 2003, and the second one in 2006. Please, see latest NWS High Seas Forecast issued by National Hurricane Center at website https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for more details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough extends from a 1008 mb low pressure over northern Colombia near 10N76W to 07N83W to 10N100W. The ITCZ continues from 10N100W to 06N120W to 08N132W to beyond 07N140W. Numerous moderate and scattered strong convection is noted within 10N87W to 09N79W to 06N77W to 02N79W to 02N80W to 10N87W and also within 14N102W to 10N90W to 03N96W to 05N108W to 12N110W to 14N102W. Scattered moderate and isolated strong convection is noted from 08N to 12N between 117W and 122W and also from 04N to 07N between 116W and 127W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please read the Special Features section for more details about the Gulf of Tehuantepec Gale Warning. A ridge dominates the offshore forecast waters west of Baja California producing gentle to moderate NW-N winds, with seas of 5 to 7 ft in mixed long period SW and NW swell. Little change in this weather pattern is expected over the next several days. Seas of 8 ft in SW swell are noted between the Revillagigedo and Clarion Islands per altimeter data. Seas will subside to less than 8 ft tonight. Gentle to moderate southerly winds will prevail across the Gulf of California. On Thu, building high pressure over the Pacific may strengthen NW winds west of Baja California. These winds may help to build seas to 7 to 9 ft west of Baja California Norte by Thu night. Long period SW swell will continue to impact the offshore waters of Mexico through Monday. Another long period SW swell event is forecast to reach the coast of Mexico between the Tehuantepec region and Cabo Corrientes on Thu. Haze and areas of smoke from agricultural fires in Mexico may reduce visibilities near the coast from the Tehuantepec region to near Cabo Corrientes. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Please read the Special Features section for more details about the Volcanic Ash Advisory for offshore of Ecuador. Fresh winds are expected in the Papagayo region by Mon night as high pressure builds N of area. Elsewhere, a weak pressure gradient will support light to gentle winds during the next several days. Long period SW swell will continue to impact the offshore waters of Central America, Colombia and Ecuador today before gradually fading. Looking ahead, another impressive SW swell event may approach SW of the Galapagos Islands by the end of the week. REMAINDER OF THE AREA... A weak 1018 mb high pressure located near 28N128W extends a ridge across the northern waters to near the Revillagigedo Islands. Gentle to moderate trades prevail with a fairly week pressure pattern in place N of the ITCZ. Long period SW swell will continue to impact the waters roughly from 03N to 14N between 95W and 110W, and from 14N to 20N between 100W and 110W, including near cabo Corrientes. Peak seas are 8 to 9 ft in this area. This swell will gradually subside through Mon. A complex low pressure system north of the area extends a weak cold front through 32N135W to 28N140W, with a second trailing front just NW of the area. The fronts will merge SE of 30N140W by late tonight, then will gradually weaken through the middle of the week. A set of long period NW swell will follow the merged fronts, building seas subside to less than 8 ft during the day Tue. A fairly weak pressure pattern will continue to prevail through the week with mainly gentle to moderate trades. The Sangay Volcano located in Ecuador near 02S78W is producing a plume of volcanic ash that extends westward over land reaching the vicinity of the Gulf of Guayaquil. The Satellite Analysis Branch (SAB) in Whashington continues to issued Volcaninc Ash Advisories. $$ GR