000 AXPZ20 KNHC 190825 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Wed Oct 19 2022 Tropical Weather Discussion for the eastern Pacific Ocean from 03.4S to 30N, east of 120W including the Gulf of California, and from the Equator to 30N, between 120W and 140W. The following information is based on satellite imagery, weather observations, radar, and meteorological analysis. Based on 0600 UTC surface analysis and satellite imagery through 0710 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: A strong cold front is moving across the Gulf of Mexico. Strong high pressure is building across the slopes of eastern Mexico creating a tight pressure gradient across the Tehuantepec region. Winds will start to funnel through the Chivela pass into the Gulf of Tehuantepec early this morning, then increase to gale force Wed afternoon. The area of high pressure will shift eastward and weaken the second half of the week, loosening the pressure gradient. Winds will diminish below gale force late Thu night, then further diminish, to 20 kt or less, this weekend. Seas will build to around 12-14 ft during the gale force winds. Please refer to the latest NWS High Seas Forecast at https://www.hurricanes.gov/marine for more details. Offshore of Southern Mexico: A tropical wave/trough of low pressure is located a couple hundred nautical miles south of the southern coast of Mexico along 99W. Shower and thunderstorm activity is starting to become more concentrated with scattered moderate and isolated strong convection noted from 13.5N to 18N between 94W and 102W. Current winds are 20-25 kt with seas of 8-10 ft. Environmental conditions appear conducive for additional development and a tropical depression is expected to form in the next day or two as the system moves generally west- northwestward, parallel to the southwestern coast of Mexico. Interests along the southwestern coast of Mexico should monitor the progress of this system. This system has a high chance of tropical cyclone formation through 48 hours. Regardless of development, increasing winds and building seas will be possible offshore southwestern Mexico, and a gale warning has been issued beginning Thu afternoon, with storm conditions possible as the system possibly rounds near Cabo Corrientes this weekend. Please refer to the latest NHC Tropical Weather Outlook at https://www.hurricanes.gov and the latest NWS High Seas Forecast at https://www.hurricanes.gov/marine for more details. ...TROPICAL WAVES... The axis of a tropical wave is near 82W north of 04N, moving west at around 10 kt. Nearby convection is discussed below. The axis of a tropical wave is near 99W north of 07N, and is described in the Special Features section above. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from Nicaragua near 11N86W to 15N98W to 09N132W to 10N135W to 12N140W. Scattered moderate isolated strong convection is noted from 09N to 15N between 92W and 114W, and from 07N to 14N between 120W and 140W. Scattered moderate convection is noted from 03N to 08N between 77W and 82W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please refer to the Special Features section above for details on an upcoming gale force gap wind event in the Gulf of Tehuantepec as well as possible tropical cyclone development offshore southwestern Mexico later this week where there is an associated gale warning. Gentle to moderate NW-N winds prevail west of Baja California from near Punta Eugenia northward. Similar winds are in the northern Gulf of California. Light to gentle winds prevail elsewhere west of 101W, locally moderate near Cabo San Lucas. Seas are 4-5 ft in S-SW well west of 101W across the open waters, mixed with NW swell west of Baja California. Seas are 1-3 ft in the Gulf of California, and 3-4 ft from the entrance of the Gulf to Cabo Corrientes. For the forecast, other than the Gulf of Tehuantepec gale force gap wind event and possibly developing tropical cyclone off southwestern Mexico and associated gale warning, gentle to moderate winds and moderate seas will prevail through next week. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gentle to moderate S-SW winds prevail across the offshore waters south of 10N, and light to gentle westerly north of 10N. Seas are in the 4-6 ft range in S-SW swell, except to 7 ft well offshore Guatemala. For the forecast, moderate to occasionally fresh S-SW winds will prevail south of the monsoon trough. Light to gentle winds will prevail north of the monsoon trough, pulsing to moderate offshore southern Nicaragua and in the Gulf of Papagayo. Moderate seas in S-SW swell will dominate the waters, building offshore Guatemala by early Thu due to a Gulf of Tehuantepec gap wind event. REMAINDER OF THE AREA... A remnant frontal trough extends from low pressure near 29.5N129W to 24N136W, with an additional surface trough from the low to 28N136W. Scattered showers are possible within 180 nm or so south-southeast of the boundary. Moderate to fresh winds are north-northwest of the low per a recent ASCAT scatterometer pass, while seas of 7-9 ft are wrapping around the back side of the low into the area across the NW waters. A ridge of high pressure is located and centered approximately 180 nm southeast- south of the trough and low. Light to gentle anticyclonic winds are under the ridge. Moderate to locally fresh winds are noted north of the monsoon trough to around 20N and west of 127W due to the pressure gradient between the ridging and monsoon trough. Seas are 6-8 ft across these waters. Gentle to locally moderate winds are elsewhere north of the monsoon trough, with seas in the 4-6 ft range. Mainly moderate southerly winds are south of the monsoon trough, locally fresh north of 05N between 97W and 115W associated with the tropical wave near 99W described in the Special Features section above. Gentle to moderate southerly winds are elsewhere south of the monsoon trough. Seas in the 6-8 ft range south of the monsoon trough to about 04N between 98W and 125W, and 5-6 ft elsewhere except 4-5 ft east of 95W. For the forecast, the remnant frontal trough will drift east across the north-central waters, eventually dissipating over the next day or so. A series of sets of NW swell will propagate across the NW and north-central waters through the next several days, occasionally building seas to around 8-9 ft with each passing set. A set of SW swell with seas of at least 8 ft will breach 03.4S and the Equator by Wed evening, reaching to 10N by the end of the week. $$ Lewitsky