000 AXPZ20 KNHC 171605 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Tue Nov 17 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 1545 UTC. ...SPECIAL FEATURES... Low pressure of 1009 mb is centered near 15N112W. This low is part of a broad area of low pressure that is located several hundred miles southwest of the coast of southern Mexico. Latest satellite imagery shows scattered moderate to isolated strong convection within 240 nm of the low in the NE quadrant and within 180 nm of the low in the NW quadrant. Overall, this convection has changed little in organization during the overnight hours. Although environmental conditions are only somewhat conducive for development, a short-lived tropical depression could still form within the next couple of days as the low moves west- northwestward or northwestward away from the coast of Mexico. Conditions are forecast to become increasingly unfavorable for further development on Thu. The low pressure has a medium chance of becoming a tropical cyclone during the next 48 hours. Please refer to the latest NHC Tropical Weather Outlook at www.hurricanes.gov for more details. Gale Warning: A tight pressure gradient resulting from strong high pressure surging southward along the eastern slopes of the Sierra Madre Oriental mountains of Mexico and over the western Gulf of Mexico is ushering strong northerly gale force winds through the Chivela Pass and out into the Tehuantepec region. This event will be a long-lived with gale force winds forecast to reach near storm force late tonight into early Wed and again Wed night into early Thu. Wave heights are forecast to build to the range of 13-20 ft by early Wed. Wave heights downstream of the Gulf of Tehuantepec are forecast to build slightly large, possibly peaking to around 21 ft late Wed night into early Thu, with the leading edge of 8 ft or greater wave heights expected to reach near 04N100W on Thu and to near 03N106W on Fri. Please read the latest NWS High Seas Forecast issued by the National Hurricane Center at website https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for more details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from central Nicaragua near 12N86W west-northwestward to 15N100W and to low pressure near 15N112W 1008 mb to a second low pressure near 12N119W 1010 mb and to another 1010 mb low pressure near 10N126W and to 08N136W, where overnight scatterometer data indicates that the ITCZ begins and to continues to beyond the area at 09N140W. Scattered moderate convection is within 60 nm south of the trough between east of 89W and between 124W and 127W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A Gale Warning remains in effect for the Gulf of Tehuantepec. Please, see the Special Features section above for details. A ridge extends across the offshore forecast waters west of Baja California producing mainly gentle to moderate winds. Wave heights are in the 5-7 ft range south of Punta Eugenia, and 7-9 ft north of Punta Eugenia due to long-period northwest swell. The swell will slowly decay through Wed allowing for wave heights north of Punta Eugenia to lower to 5-7 ft. The latest Ascat pass shows lighter wind speeds in the light to gentle range over the southern part of the Gulf. The earlier moderate to fresh northwest winds over the northern part of the Gulf of California have become light and variable winds, and little change is expected with these winds through Thu. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, and WITHIN 750 NM OF ECUADOR... Enhanced southwesterly flow of moderate to fresh speeds is occurring south of the monsoon trough portion offshore Panama along with wave heights of 6-7 ft. This enhanced flow has arisen primarily from the broad cyclonic circulation around major Hurricane Iota now inland norther Nicaragua. Elsewhere, moderate to fresh southwest winds are present south of the monsoon trough east of 100W, with mainly gentle west to northwest winds north of the monsoon trough. Wave heights are in the 5-7 ft range. Wave heights generated in the Tehuantepec region will propagate across the offshore waters of El Salvador, extreme southern Honduras and Nicaragua through late Wed. Scattered showers and thunderstorms in a band ahead of Iota are moving offshore the coasts of El Salvador, extreme southern Honduras and Nicaragua. This activity is likely to spread westward into the offshore waters of the aforementioned countries through Thu. Some of this activity may contain strong gusty winds. REMAINDER OF THE AREA... See the Special Features section above for the details on a broad low pressure that is located several hundred miles southwest of the southern coast of Mexico. A 1018 mb high is centered near 25N115W. The associated ridge dominates the waters north of 17N and west of 110W. Gentle to moderate trades are along the southern periphery of the ridge west of 115W as noted in an overnight ASCAT pass. Wave heights are in the 6-7 ft range within that region. The overnight ASCAT passes suggested that weak low pressure of 1011 mb is near 12N119W and a 1010 mb low is near 10N126W. Scattered moderate convection is within 120 nm in the SE quadrant of the low near 10N126W. The ridge to the north of these lows will weaken through Tue as a cold front just northwest of the area moves into the northwest part of the area. The front will reach a position from near 32N132W to 27N135W and to 26N140W early Tue, then begin to dissipate from near 32N125W to 26N132W, and continue to dissipate as a stationary front from there to near 23N140W. Large northwest swell, producing wave heights in the range of 8-11 ft, will follow in behind the front today, then gradually decay through Thu. $$ Aguirre