000 AXPZ20 KNHC 052120 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2120 UTC Thu Dec 5 2019 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... Gulf of Tehuantepec Gale Warning: Fresh to strong N to NE winds will pulse across the Gulf of Tehuantepec through Fri morning. A cold front is expected to move across the Gulf of Mexico Fri through Sat, and high pressure will build over eastern Mexico behind the front. This will support gale force gap winds over the Gulf of Tehuantepec beginning late Fri night and continuing through Sat night. Seas will build to 12-13 ft downstream of the Gulf on Sat night, then subside on Sun as wind speeds diminish to fresh to strong speeds. Looking ahead, another gale force gap wind event could affect the Gulf of Tehuantepec during the middle of next week, although the timing remains uncertain given the lack of model agreement. See latest NWS High Seas Forecast issued by National Hurricane Center under AWIPS/WMO headers HSFEP2/FZPN03 KNHC or at website https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for more details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 06N77W to 05N93W to 1011 mb low pressure near 09N113W to 09N121W, then resumes from 10N131W to 09N138W. The ITCZ extends from 09N138W to beyond 08N140W. Scattered moderate isolated strong convection is noted within 120 nm south of the monsoon trough between 101W and 106W. Scattered moderate convection is occurring from 03N to 06N between 81W and 85W, within 180 nm SE quadrant of low center, and from 08N to 10N west of 135W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features section above for more details on the Gulf of Tehuantepec Gale Warning. A dissipating stationary front extends across the northern Gulf of California to near 25N118W. Recent scatterometer data indicates light to gentle breezes prevail across most of the region under a weak pressure pattern. Fresh to strong northerly gap winds are noted over and downstream of the Gulf of Tehuantepec. Fresh NW to N winds will develop over the central and southern Gulf of California tonight and persist through Sat night. Large NW swell will enter the Baja California Norte waters on Sat, with offshore seas building to 8-12 ft by Sat night. This swell will continue spreading SE across the region Sat night through Sun night, then decay Mon into Mon night. The pressure gradient over Baja California will strengthen early next week, resulting in fresh northerly winds offshore and over the Gulf of California. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Strong NE to E winds will pulse across and downstream of the Gulf of Papagayo through Tue, with seas peaking between 8-9 ft downstream of the Gulf each morning. SW winds will freshen off the coast of Colombia late tonight through Sat. Otherwise, gentle to moderate S to SW monsoon flow will persist across the offshore waters of Costa Rica, Panama, Colombia, and Ecuador during the next several days. REMAINDER OF THE AREA... A cold front extends across the NW waters from 30N136W to 27N140W. Recent scatterometer data shows fresh to strong NW winds behind the front, with fresh SW flow noted ahead of the front. The front will cross the northern waters through Fri night, then stall and weaken on Sat. Very large NW swell associated with this system will move into the NW portion tonight, then propagate SE while gradually decaying through the weekend. Seas will build to greater than 12 ft over the northern waters Fri through Sat, peaking in excess of 20 ft over the far NW portion on Fri. Elsewhere, decaying NW swell lingers over the waters south of 15N and west of 100W, with the latest altimeter data indicating wave heights have subsided to 7-8 ft across most of the region. These seas will continue subsiding through tonight. $$ Reinhart