606 AXPZ20 KNHC 070940 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Sat Dec 7 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 0600 UTC surface analysis and satellite imagery through 0845 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: A cold front that extends across the NW Gulf of Mexico will continue moving SE through Sat. High pressure is currently building southward over eastern Mexico and into the Tehuantepec region. The enhanced north- south pressure gradient is presently supporting strong northerly gap winds over the Gulf of Tehuantepec, and will increase to gale force in the next few hours, and continue through Sat night. Seas will peak 12-14 ft downstream of the Gulf on Sat night, then subside on Sun as the pressure gradient weakens and wind speeds diminish to fresh to strong speeds. Looking ahead, another gale force gap wind event could affect the Gulf of Tehuantepec Wed into Thu as a stronger cold front crosses the Gulf of Mexico. 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 09N74.5W to 08.5N86W to 06N95W to 06.5N101W. The ITCZ continues from 06.5N101W to 06.5N109W then resumes from low pres 1013 mb near 06.5N110W to 06.5N120W to 06N132W to beyond 08.5N140W. Scattered moderate convection is noted within 120 nm of the monsoon trough between 82W and 97W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Fresh to locally strong NW winds continue over the central and southern Gulf of California between a low pressure trough over western Mexico and a weak high pressure ridge over the Baja California offshore waters. These winds will persist through Sat, then diminish to moderate speeds on Sun. Peak seas are currently 5-6 ft across southern portions of the Gulf tonight and will begin to gradually subside by morning. Elsewhere, gentle winds prevail across most of the offshore waters, as weak high pressure prevails across the offshore waters, ahead of a cold front moving SE across the far NW waters approaching 125W. Clusters of scattered moderate convection are seen in satellite imagery well ahead of the front and moving into the offshore waters of Baja California Norte and southern California. Elsewhere across the Mexican offshore waters, variable and gentle winds prevail, except for increasing northerly gap winds over the Gulf of Tehuantepec. Please see the Special Features section above for more details on the Gulf of Tehuantepec Gale Warning. Large NW swell will enter the Baja California Norte waters Sat, with offshore seas building to 8-11 ft by Sat night. This swell will continue spreading SE across the region Sat night through Sun night, then decay Mon into Mon night. A high pressure ridge will build across the northern waters Sun night into Mon, which will result in freshening northerly winds offshore and over the Gulf of California through early next week. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... The latest GOES-16 satellite imagery shows scattered moderate to strong convection continues along the monsoon trough off the coast of Colombia, Panama and Costa Rica, and extending westward to south of the Gulf of Tehuantepec. This weather is expected to continue shifting westward today. Strong NE to E winds will pulse to around 25 kt each night across and downstream of the Gulf of Papagayo through Wed, with seas peaking between 8-9 ft downstream of the Gulf each morning. Elsewhere, 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... Deep low pressure well north of the area is pushing a cold front eastward across the NW waters. The front extends from 30N125W to 27N131W to 23N140W, where it is becoming stationary. Recent scatterometer data showed the strong winds associated with this system remain north of 30N, with moderate to fresh winds noted from 28N to 30N and west of 130W behind the front. Associated large NW swell is spreading across the region, as seas greater than 12 ft dominate the waters northwest of the front. Recent altimeter data suggests seas peaking around 18 ft along 30N. This front will continue slowly moving eastward across the northern waters tonight, then weaken and dissipated as it crosses 120W Sat into Sat night. Large NW swell will continue propagating SE through the weekend. Seas will remain greater than 12 ft over the northern waters through Sat, then subside Sat night through Sun. Looking ahead, another cold front will approach the NW portion of the discussion area on Mon, introducing new NW swell into the NW waters through the middle of next week. $$ Stripling