000 AXPZ20 KNHC 111555 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 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 1200 UTC surface analysis and satellite imagery through 1500 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: A locally tight pressure gradient over the Tehuantepec region was supporting minimal gale force northerly winds this morning. The pressure gradient is weakening and winds will diminish below gale force in the next few hours. Fresh to strong northerly winds will then blow through Tue morning before diminishing. Light onshore flow should prevail for the remainder of the week. Seas up to 12 to 13 ft this morning will subside to less than 8 ft by Tue afternoon. Please see the 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 low pressure over northern Colombia near 10N74W to 07N84W to 11N100W to 10N110W. The ITCZ continues from 10N110W to 07N120W to 06N140W. Numerous moderate and scattered strong convection is noted within 15N93W to 08N78W to 04N77W to 01N79W to 04N91W to 10N97W to 15N93W. Scattered moderate and isolated strong convection is noted within 12N113W to 07N102W to 03N104W to 05N119W to 10N119W to 12N113W, and from 03N to 08N between 129W and 138W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please read the Special Features section for more details about the Gulf of Tehuantepec Gale Warning. Haze and areas of smoke from agricultural fires in Mexico may reduce visibilities near the coast from the Tehuantepec region to near Cabo Corrientes to Baja California Sur per recent observations. A ridge axis extends from 1018 mb high pressure near 25N128W SE across the Revillagigedo Islands to near 14N100W. Gentle to moderate NW-N flow dominates the offshore waters along with seas of 5-7 ft, except 2-4 ft near the entrance to the Gulf of California and seas of 3 ft or less inside the Gulf of California under mainly light to moderate southerly flow. A dissipating cold front will approach the waters W of Baja California Tue night into early Wed. High pressure will build in behind the old boundary with NW-N winds increasing to moderate to fresh offshore of Baja California Wed night through Fri night. These freshening winds will help to build seas to 7-10 ft offshore of Baja California during this same time period. Otherwise, little change is forecast for the rest of the week. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... The Sangay Volcano located in Ecuador near 02S78W is producing a plume of volcanic ash that extends well SW over land reaching the vicinity of the eastern shore portion of the Gulf of Guayaquil. The Satellite Analysis Branch (SAB) in Washington, D.C. continues to issue Volcanic Ash Advisories, however the offshore waters are not currently forecast to be impacted. Light to moderate winds will continue to prevail across the offshore waters, except moderate to fresh offshore winds in the Papagayo region during the next few late nights/early mornings. Seas will be mainly 4-7 ft in mixed long period SW and NW swell. A new set of long period SW swell will reach the waters offshore of Ecuador Thu night into early Fri with seas building to near 8 ft SW of the Galapagos Islands Fri and Fri night. REMAINDER OF THE AREA... A ridge axis extends from 1018 mb high pressure near 25N128W SE across the Revillagigedo Islands to near 14N100W, with another ridge extending SW of the high to 21N140W. A cold front extends from 30N132W to 26N140W. Mainly gentle to moderate trades prevail ahead of the front, except light to gentle anticyclonic flow near the ridging. Seas are 5-8 ft in mixed swell ahead of the front, mainly long period SW and NW swell, per recent altimeter data. Moderate to fresh NW winds are noted behind the front along with a set of NW swell building seas to 8-10 ft behind it. The front will weaken as it continues to traverse the northern waters while the set of NW swell gradually decays as it propagates E-SE, subsiding below 8 ft by Tue afternoon. Trades will increase slightly to moderate to fresh due to lower pressures along the ITCZ which will occassionally support seas around 8 ft through the week. A set of long period SW swell may breach the equator Thu, building seas to 7-9 ft S of 10N and W of the Galapagos to 120W through Fri night. The next front may approach 30N140W from the NW on Fri night. $$ Lewitsky