000 AXPZ20 KNHC 042219 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Wed Nov 4 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 1800 UTC surface analysis and satellite imagery through 2120 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: Northerly gales continue across the Gulf this afternoon, and extend downwind to near 13N95.5W, with peak seas estimated to be 19 ft. The gales are due to a tight pressure gradient created by building high pressure north of the area over the Gulf of Mexico and across the eastern slopes of the Sierra Madre Oriental mountains. Swell generated from this Tehuantepec event will produce a large plume of 12 ft or greater seas that will extend about 500 nm southwest of the Gulf of Tehuantepec. Winds will gradually taper off to just below gale force by midday Fri, as the high pressure north of the area weakens and shifts east. Marine interests transiting across or in the vicinity the Gulf of Tehuantepec should be aware of this gap wind event, and take necessary action to avoid hazardous marine conditions over the affected waters. Please refer to the latest High Seas Forecast issued by the National Hurricane Center at: https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for further details. Potential Heavy Rainfall event: Hurricane Eta is moving slowly across central Nicaragua, and producing a surge of moist southwesterly flow across the tropical eastern Pacific that will support heavy to torrential rainfall across portions of Central America through mid week. Eta is likely to cause life-threatening flash flooding and river flooding across portions of Central America, along with landslides in areas of higher terrain. Eta is expected to produce rainfall accumulations of 15 to 30 inches (375 to 750 mm) across central and northern Honduras into NE Guatemala, while SW onshore winds are expected to yield rainfall accumulations of 10 to 20 inches (250 to 500 mm) across coastal sections from NW Costa Rica to Nicaragua to far southern Honduras. Please refer to statements provided by your local national meteorological agency for more details. Farther west, Tropical Storm Odalys is centered near 17.7N 120.7W at 2100 UTC moving NW at 15 kt. Estimated minimum central pressure is 1003 mb. Maximum sustained wind speed is 40 kt with gusts to 50 kt. Visible satellite imagery this afternoon showed the low level center of Odalys moving to the southwestern edge of the strong convective cloud tops, and has become exposed. Scattered to numerous strong convection is observed within 180 nm in the northeast semicircle, while scattered moderate convection is noted from 13.5N to 17.5N between 117W and 121.5W. Odalys will change little in intensity overnight as it continues to move WNW, then gradually weaken to a depression by Thu night and move more westward Fri as a remnant low as it reaches cooler waters and drier more stable air. Please read the latest NHC Public Advisory at https://www.nhc.noaa.gov/text/MIATCPEP5.shtml and Forecast/ Advisory at https://www.nhc.noaa.gov/text/MIATCMEP5.shtml for more details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 12N87W to 06N102W to 13N111W, then resumes southwest of Odalys near 13N122W to 09N133W. ITCZ extends from 09N133W to BEYOND 09N140W. Scattered moderate isolated strong convection is noted north of 06.5N to the coasts between 83W and 93W. Scattered moderate convection noted within 120 nm either side of trough and ITCZ west of 122W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please refer to the Special Features section above for details on the Gulf of Tehuantepec Gale Warning. Of note, the 20-year climatology of the Tehuantepec gap wind events indicates that most gale-force events occurred during November and December while most events reaching storm-force occurred in January. Based on these updated records, the first storm-force wind event of each cold season can be expected to occur as early as mid- November. A modest high pressure ridge northwest of Baja California is supporting gentle to moderate northerly winds with seas 4 to 6 ft in NW swell. Seas have begun to build to 7-9 ft south through southwest of the Revillagigedo Islands today as swell from the Tropical Storm Odalys is moving into the area, and Odalys makes its closes point of approach to the west of Clarion Island. Seas will build to 5 to 7 ft elsewhere off Baja California after mid week in a mix of NW swell and southerly swell emerging from Odalys. A cold front will bring strong NW winds to the waters off Baja California Norte and inside the northern Gulf of California Fri night. Gentle winds will persist south of Cabo Corrientes outside of the Gulf of Tehuantepec plume, with seas of 4 to 6 ft in mostly southerly swell. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, and WITHIN 750 NM OF ECUADOR... Moderate to fresh south to southwest onshore winds prevail from 03N to the coasts between Panama and the Gulf of Fonseca. Fresh to strong SW winds are expected to become concentrated in a band from north of the Galapagos Islands near 05N to the coasts between NW Costa Rica and the Papagayo region Thu through Fri and raise seas to 10-12 ft. Large seas generated by the gale force gap wind event in the Tehuantepec region are propagating across the offshore waters of Guatemala and El Salvador, mixing with SW swell and will maintain seas in the 10 to 15 ft range there through into Fri. Farther south, a combination of fresh SW winds and building SW swell support seas to 9 ft off western Panama and near the Azuero peninsula. As Hurricane Eta continues to move through Nicaragua and Honduras, expect moderate to fresh onshore wind flow to persist across the Pacific offshore waters from western Panama to Guatemala through Sat then diminishing by Sun. REMAINDER OF THE AREA... High pressure dominates north of 20N, with the ridge extending SE from a 1027 mb high pressure centered near 34N133W. This pattern is supporting gentle to moderate NE winds over most area north of the monsoon trough and outside of Odalys, with isolated areas of fresh trades closer to the monsoon trough. Seas are 6 to 8 ft in NW swell to the W of 120W, except higher near Tropical Storm Odalys, and in an area of building seas between 12N to 21N west of 134W related to a large area of fresh trade winds farther west. Farther east, seas are 8 to 16 ft over tropical waters east of 110W due to NE swell emerging out of Tehuantepec and longer period SW swell moving into the region. The current trends will persist through Thu. Lingering swell from Odalys will mix with new NW swell expected to invade the waters north of 20N. Seas may reach as high as 16 ft in this NW swell north of 20N and east of 128W, following a strong front expected to move into the area. Meanwhile east of 120W, the gale to storm force wind event in Tehuantepec will finally begin to taper off on Fri, with related seas subsiding accordingly. SW swell will persist however through weeks end. $$ Stripling