000 AXPZ20 KNHC 222212 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Thu Dec 22 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 1800 UTC surface analysis and satellite imagery through 2030 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Storm Warning: A strong Arctic cold front is forecast to cross the Gulf of Mexico this evening through Fri evening. Very strong high pressure will build behind the front across eastern Mexico and through the Chivela Pass, resulting in fresh to strong winds returning in the Gulf of Tehuantepec by sunrise Fri, rapidly increasing to gale force by early Fri afternoon, then to storm force Fri evening into early Sat. Gales could then last through at least Mon night. This event will produce a very large plume of winds by Fri night, expanding across the Tehuantepec region between 93.5W and 95.5W and extending offshore to near 11N. Very large and steep seas will quickly develop with this gap wind event, peaking at around 20-21 ft Fri night through Sat morning. Please read the latest High Seas Forecast issued by the the National Hurricane Center at website https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for more details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 10N75W to 09.5N86W to 07N104W. The ITCZ axis extends from 07N104W to 07N116W to 06N130W, then resumes near 06N134W to beyond 05N140W. Scattered moderate isolated strong convection is noted from 03.5N to 06.5N E of 85W, and within 120 nm N of the ITCZ between 101W and 136W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features section for information about an upcoming storm force gap wind event in the Gulf of Tehuantepec. High pressure has weakened across the southern Gulf of Mexico and Tehuantepec region today, resulting in weakening winds across Tehuantepec. Moderate gap winds across the immediate Gulf merge with easterly trade winds well offshore and continue beyond 100W. Seas have subsided to 4-5 ft across the Gulf waters and are 6-7 ft much farther offshore in fading NE swell. Gentle to light and variable winds prevail elsewhere between Tehuantepec and the waters offshore of Manzanillo. Elsewhere, high pressure has shifted southward to near 30N126W and extends a ridge southwestward into the tropical Pacific. The weak ridge is combining with lower pressure across mainland NW Mexico to produce moderate NW winds across central and southern portions of the Gulf of California, where seas are 3-5 ft. Elsewhere across the Baja offshore waters to Cabo Corrientes, N to NE winds are moderate or weaker with seas of 3-5 ft. For the forecast, high pressure will remain generally stationary W of the offshore waters through Fri before weakening and shifting northward over the weekend. The associated ridge will change orientation and build southeastward Fri through Sat, and act to strengthen local winds to moderate to locally fresh across the Baja offshore waters, and fresh to locally strong inside the Gulf of California. High pressure will weaken Sun night through Mon to produce a weakening trend in winds across the waters N of Cabo Corrientes. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Fresh NE to E gap winds are occurring over the Gulf of Papagayo region, and extend offshore to 89W. Seas are 5-7 ft there. Light winds prevail elsewehre to the N, where seas are 4-6 ft in mixed NW swell from the most recent and ending Gulf of Tehuantepec gap wind event, and E swell from the Gulf of Papagayo. Elsewhere winds are moderate or weaker with seas 3-5 ft. For the forecast, fresh to strong NE to E gap winds will continue to pulse in the Papagayo region through the rest of the forecast period. Gentle to occasionally moderate winds will continue elsewhere for the next several days. Large NW swell is expected in the Guatemala offshore zone early Sat through at least Mon night due to the large area of gale to storm force winds that will develop across the Gulf of Tehuantepec region over the next several days. REMAINDER OF THE AREA... A complex low pressure system northwest of the area has an associated cold front that has dissipated across the far NW waters near 30N140W. The low and associated front will continue to shift northeastward today, remaining just outside of our forecast area. Moderate to fresh S winds to the east of the cold front are north of about 27N between 133W and 138W. Seas reach up to 13 ft in mixed wind waves and NW swell across this area. Elsewhere, 1024 mb high pressure is centered near 30N126W and extends a ridge SW to near 22N138W. The pressure gradient to the south of this ridge is produce a broad area of moderate to fresh trade winds between the ITCZ, along about 05N 06N, and 20N and to the W of 117W. A few low level perturbations are moving westward through this zone, and producing areas of strong winds between 122W and 140W. Seas south of 20N are 7 to 10 ft in NW swell to the W of 120W, and 10-11 ft in the areas of strong winds. ridging extends from high pressure centered north of area through 30N127W to 22N140W, and from 30N127W to 17N110W. Moderate or weaker winds are under the ridge along with seas of 4-6 ft north of 20N and east of 130W. A small 1010 mb low pressure center is along the ITCZ near 06N119W. Overnight ASCAT scatterometer data showed local winds of 20-25 kt near the trough with seas of 7-8 ft likely. The moderate pressure gradient between the ridge and low pressure over the ITCZ is forcing moderate to fresh NE to E trades elsewhere from 06N to 17N west of 116W. Seas are 6-9 ft. Another perturbation in the trade winds is along 101W, where afternoon scatterometer data showed NE to E winds to 25 kt between 08N and 10N. Seas are 8-9 ft in this area. For the forecast, S winds in our NW corner waters will continue to slowly subside today, and then become moderate to fresh Fri and Fri night, then fresh to strong through the weekend as another cold front approaches the area from the W. Seas in that area will subside to below 12 ft this evening, while residual NW swell will maintain seas of 7-11 ft west of about 125W for the next few days. The NE to E trades are expected to have little change for the next few days. New NW swell will build seas to 12-15 ft in the far NW corner by the end of the weekend into early next week. $$ Stripling