000 AXPZ20 KNHC 212205 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Sat Jan 21 2017 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 FEATURE... High pressure building behind a strong fast moving cold front in the southwestern Gulf of Mexico Monday will induce gale force winds over the Gulf of Tehuantepec beginning around 0900 UTC Monday. The high will slide quickly eastward, which will allow winds to diminish below gale force by 0000 UTC Tuesday. Please see the latest East Pacific high seas forecast under AWIPS/WMO headers HSFEP2/FZPN03 KNHC for further details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The ITCZ extends from 07N97W to 08N107W to 06N116W to 07N124W to 05N128W to 03N140W. No significant convection. ...DISCUSSION... ...A series of strong cold fronts and a prolonged period of unusually large swell will affect most of the forecast area... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A surface trough, what is left from a cold front moving into northwest Mexico, extends from 31N112W across Baja California to 23N121W. A small area of fresh to strong westerly winds is north of 28N in the Gulf of California. Strong northwest winds and seas of 12-21 ft are affecting waters north of 25N. The large northwest swell will continue to propagate southeast, and will continue into the deep tropics the next several days. By Sunday morning, seas will build to 20 ft off Baja California Norte. The leading edge of high seas will reach Socorro Island late Sunday morning. Ridging behind the front will allow strong northerly winds to spread to the southern Gulf of California and off Cabo Corrientes by late Sunday. Another cold front will produce a reinforcing set of long period NW swell, which will maintain seas in the 12 to 20 foot range through Tuesday. Strong winds sustaining the swell event will diminish Tuesday as the high weakens, with seas finally decreasing below 12 ft in offshore Mexico waters by Wednesday night. However, seas of 8 to 10 ft will remain west of 100W through the end of the week. High pressure building in behind a strong cold front in the Gulf of Mexico will increase the pressure gradient across the Isthmus of Tehuantepec and cause gap winds to increase to gale force over the Gulf of Tehuantepec Monday morning. Please see the special features section for more details. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Light to gentle southeast to east winds will prevail across most of the region through Tuesday. Seas will be generally 3-5 ft in the forecast waters. Fresh to strong gap winds will pulse in the Gulfs of Papagayo and Panama Tuesday night and Wednesday night as high pressure passes north of the Caribbean basin. REMAINDER OF THE AREA... The pressure gradient between a cold front approaching southern California and high pressure centered near 26N125W supports strong northwesterly winds across northern waters west of 132W. A large northwesterly swell event is spreading across the waters with 12 ft seas dominating north of 21N and reaching as high as 26 ft along 30N. Seas of 8 ft or greater extend northwest of a line from 22N109W to 04N140W. Large swell will continue to sweep southeastward with 8 ft seas nearing the equator Sunday night. Global models continue to show gale force winds associated with the cold front moving across the northern waters remaining just north of 30N through Sunday night. These winds will help to re- enforce the northwest swell with seas of 18 to 23 ft west of the front where the near gale winds are occurring. Mainly gentle to moderate winds will prevail elsewhere, with 4-7 ft seas expected through Monday. NE swell from the Tehuantepec high wind event will increase seas to 8-10 ft Monday night. $$ Mundell