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Eastern Pacific Tropical Outlook
Latest Eastern Pacific Tropical Report
Expires:No;;124658 AXPZ20 KNHC 311541 TWDEP

Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Sat Oct 31 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 1515 UTC.

...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: High pressure and cooler, denser air behind a frontal boundary that moved across the southwest Gulf of Mexico and is currently stationary over the Yucatan Peninsula continues to spill through the isthmus of Tehuantepec. Earlier scatterometer data confirmed gale force winds peaking around 45 kt. Large fresh seas have built due to these winds, near 15 ft. Winds will diminish slightly to minimal gale force through tonight with resultant peak seas also subsiding to 12 ft. A reinforcing cold front is expected to move into the southwest Gulf by early Sun allowing for gale force winds to increase back to near 45 kt Sun night through early next week. Northerly swell will mix with longer period southerly swell to support seas in excess of 8 ft well downstream of the Gulf of Tehuantepec, with peak seas building back to near 20 ft early next week. 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: Heavy rainfall is possible across portions of Central America late this weekend into early next week, particularly western Panama and Costa Rica to begin with, then spreading northwestward early next week. If heavy rainfall occurs, flash flooding and mudslides may be possible. Refer to statements provided by your national meteorological service for more details. ...TROPICAL WAVES... A tropical wave axis is along 91W from 02N-16N, moving W at around 10 kt. Associated convection is described below. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 08N81W to 1010 MB low near 12N111W to 10N140W. Scattered moderate convection is noted within 120 nm on either sides of the axis between 92W-138W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please refer to the Special Features section above for details on the Gulf of Tehuantepec Gale Warning. High pressure west of Baja California is supporting gentle to moderate northerly breezes across the Mexican offshore waters off Baja California and the Gulf of California. Seas of 2 to 4 ft prevail in both the open waters and in the Gulf of California. Seas will build to 4 to 6 ft in the waters of Baja California by early next week. Elsewhere, little change is expected through the next several days. Gentle winds persist south of Cabo Corrientes outside of the Gulf of Tehuantepec plume, with seas of 4 to 6 ft in mostly southerly swell. Little change is expected. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, and WITHIN 750 NM OF ECUADOR...

Moderate south to southwest winds will prevail south of the monsoon trough through Sun, with isolated areas of fresh winds ahead of a tropical wave. Seas are expected to increase offshore of Guatemala and El Salvador through Sat night due to gale force winds in the Gulf of Tehuantepec pushing northerly waves into the area. Larger seas are expected early next week across this same area due to greater coverage and strength of the Tehuantepec gap winds NW of the area. Elsewhere seas are mainly 5 to 7 ft in mainly long period southerly swell. Seas will build slightly to the south and east of the Galapagos Islands late this weekend into early next week due to reinforcing southerly swell. Moderate offshore gap winds are expected across the Papagayo region through Sun before turning onshore Mon through Tue. REMAINDER OF THE AREA... High pressure dominates the waters north of 20N. The gradient between the high pressure and lower pressures associated with the monsoon trough will continue to support moderate to locally fresh NE trade winds from the monsoon trough to 20N and west of 115W, for the next several days. Seas are 5 to 7 ft across this region, in a mix of swell and easterly wind waves. Little change is expected through the weekend. A complex low pressure system north of the Hawaiian Islands is forecast to move NE through the weekend. A weak trailing cold front may slip southeast of 30N140W by early next week with winds remaining 20 kt or less. Associated seas will build to 8-9 ft behind this boundary Sun night through Mon night, impacting the waters north of 25N and west of 135W. South of the monsoon trough, moderate to fresh S to SW winds prevail between 100W and 140W, where seas are 5 to 8 ft. Minor fluctuations in winds and seas are expected across this area through the weekend.

Looking ahead, computer models suggest that a tropical wave moving offshore of SW Mexico Sun and Mon could spawn a low pressure center forming west of the offshore waters in the vicinity of 10N110W by Mon morning, and move WNW through mid week. There is broad disagreement among the main global models, and confidence remains low on the exact locations and intensity of this low pressure at this time. $$ ERA