000 AXPZ20 KNHC 152200 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1857 UTC Mon Oct 15 2018 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 2100 UTC. ...SPECIAL FEATURES... The center of Tropical Storm Tara is located near 18.0N 104.5W at 15/2100 UTC or 60 nm S of Manzanillo Mexico drifting NW or 305 degrees at 2 kt. Estimated minimum central pressure is 1000 mb. Maximum sustained wind speed is 45 kt with gusts to 55 kt. Numerous moderate to strong convection is noted within 90 nm NW and 60 nm SE semicircles. The tropical storm could become stationary at times. A slightly faster westward motion is forecast to begin after mid-week. On the forecast track, the center of Tara is expected to remain near or just offshore of the southwestern coast of Mexico during the next couple of days. Some slow strengthening is forecast during the next couple of days. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCPEP2/WTPZ32 KNHC for more details. Gulf of California: A Gale Warning remains in effect for the northern Gulf of California through this evening. A recent ASCAT pass provided observations of near gale force winds across the northern Gulf of California. These winds are the result of robust high pressure building over the Great Basin of the United States. Fresh to strong winds are expected to persist across much of the Gulf through early Wed. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from a 1006 mb low pressure centered over the SW Caribbean near 15N83W, then across Central America and the Gulf of Tehunatepec to near 16N100W to 13N110W to 10N120W to 11N130W to 09N140W. Scattered moderate to isolated strong convection is within about 180 nm S of the monsoon trough between 93W and 105W, and within 120 nm between 105W and 114W. Numerous moderate to scattered strong is from 09N to 11N between 127W and 136W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Latest scatterometer data indicate moderate to locally fresh NW winds N of Punta Eugenia, and gentle to moderate NW to N winds elsewhere across the offshore forecast waters W of Baja california. A ridge will continue to dominate the offshore waters W of Baja California Peninsula producing mainly gentle to moderate NW to N winds, and seas generally in the 4 to 6 ft range, with the exception of moderate to fresh winds N of Punta Eugenia tonight through Tue night. Seas are forecast to increase a foot or so by the end of the forecast period as mixed swell generated by Tropical Storm Tara arrives. Gulf of Tehuantepec: Next gap wind event is forecast to start early on Wed with seas rapidly building to 10 ft by Wed afternoon. This event will be associated with a ridge building behind a cold front across the eastern slopes of Sierra Madre Mountains in Mexico and the western Gulf of Mexico. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Moderate to fresh SW monsoonal flow will continue across the region through Tue, with showers and thunderstorms expected to continue along the Pacific coast of Central America. Long period cross-equatorial SW swell will maintain 5 to 8 ft seas across the forecast area during this time frame. By Tue night and Wed, marine guidance suggests an increase in winds and seas across the offshore waters from northern Costa Rica to Guatemala. This appears to be associated with an area of low pressure forecast to develop a couple of hundred miles south of Guatemala and the southeastern coast of Mexico around mid-week. REMAINDER OF THE AREA... A 1021 mb high pressure located near 30N127W extends a ridge across the northern forecast waters. The pressure gradient between the ridge and a cold front approaching from the W is resulting in fresh to strong southerly winds across the far NW waters, mainly NW of a line from 30N138W to 26N140W. Moderate to locally fresh trades are noted S of 15N and N of the monsoon trough W of 125W. The cold front is forecast to reach a position from 0N138W to 27N140W on Tue, and from 30N138W to 27N138W to 25N140W on Wed, when it is forecast to become stationary. Long period NW swell will follow the front building seas of 8-10 ft. Satellite-derived wind and altimeter data confirmed the presence of moderate to fresh monsoonal flow across much of the forecast waters. Winds increase near the convection. An area of 7 to 9 ft in long period SW swell is noted south of the monsoon trough and mainly between 100W and 120W. Looking ahead, an area of low pressure is forecast to develop a couple of hundred miles south of Guatemala and the southeastern coast of Mexico around mid-week. Environmental conditions are forecast to be conducive for development, and a tropical depression is likely to form by late week while the system moves west-northwestward near the southern coast of Mexico. The latest Tropical Weather Outlook gives this system a high change of tropical cyclone formation through 5 days. $$ GR