000 AXPZ20 KNHC 160356 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Wed Jan 16 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 0000 UTC surface analysis and satellite imagery through 0215 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: Near gale to minimal gale force north to northeast winds are funneling through the Chivela Pass and into the Gulf of Tehuantepec. These winds were captured by both Ascat and Windsat data from Tue afternoon that also revealed these winds reaching south to near 14.5N and between 94W and 96W. Strong to near gale force north to northeast winds are south of 14.5N to near 12N and between 95W and 98W. The gale force winds are forecast to continue into early Wed afternoon, at which time high pressure over the northern Gulf of Mexico will shift eastward and weaken. This was allow for the strong pressure gradient over southeastern Mexico to slacken, enabling the gale force winds to lower to just below gale force. The winds will diminish further, to strong category by late Fri. Maximum seas presently reaching 14 ft with the gale force winds will gradually subside through the end of the week. For more specific marine information, please refer to the latest East Pacific High Seas Forecast under WMO/AWIPS headers FZNT02 KNHC/HSFEP2. In the long term, a rather powerful storm-force gap wind event is possible beginning on Sun. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A trough extends from central Colombia to the coast at 04N78W and continues to 04N90W, where it briefly ends. A 1009 mb low is centered near 06N105W. Latest scatterometer data indicates that the ITCZ then resumes at 04N107W and continues to 07N123W to 07N131W and to beyond 06N140W. Scattered moderate convection is seen within 120 nm north of the ITCZ between 100W and 102W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Winds west of Baja California are light and variable and will remain below strong breeze through Fri morning. A developing storm over the U.S. Great Basin will help to tighten the pressure gradient that is expected to lead to strong northwest to north winds Fri through Sat night. Northwest swell inducing seas in the range of 8 to 10 ft is currently propagating through these waters, which will gradually weaken through Thu night. A more pronounced and extensive set of northwest swell, with resulting seas possibly peaking up to 15 ft will begin to arrive beginning early on Fri and gradually subside through Sun. Gulf of California: Gentle to moderate northwest winds will continue over the Gulf through early Sat. These will become strong northwest winds Sat through Sun due to the developing storm system over the Great Basin. Wind waves could reach 8 ft during the weekend. Gulf of Tehuantepec: See discussion above for on-going Gale Warning. Substantial high cloudiness with isolated showers are being advected across the water south of Baja California and into western Mexico ahead of a mid to upper-level trough with axis roughly along 122W. These should gradually diminish over the next couple of days. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: An Ascat pass from this afternoon indicated strong northeast winds across the Gulf due to a moderate pressure gradient over the western Caribbean and Central America. The strongest winds and areal coverage will be greater late night and early morning hours as nocturnal drainage augments the winds. Winds are expected to briefly increase to near gale force late Thu night before diminishing back to mainly strong winds Fri. Peak seas will be in the range of 8-10 ft, except possibly up to 11 ft Thu night. These conditions will continue through Sat. Gulf of Panama: An Ascat pass from thus afternoon showed strong northeast winds over the Gulf. The strongest winds and areal coverage will be greater late night and early morning hours as nocturnal drainage augments the winds. Peak seas will reach about 8 ft. These conditions will continue through Fri before weakening on Sat and Sun. REMAINDER OF THE AREA... Strong southwest winds north of 29N between 122W and 124W, with seas of 11-14 ft in mixed southwest wind waves and northwest swell will diminish to fresh winds overnight tonight as strong southwest winds begin to move into the far northwest corner of the area ahead of the next cold front. This cold front will move across the extreme northwest waters early on and reach from near 32N133W to 27N140W by early Wed evening. The front will then begin to weaken shortly thereafter as it moves across the northern waters through Thu night. West to northwest winds behind the front will be fresh to strong late tonight into early Wed, then quickly drop off to moderate to fresh winds by Wed evening and to mainly gentle west winds early on Thu as the front reaches from near 32N12W to near 29N131W. The main story elsewhere is that long-period northwest swell producing seas of least 8 ft covers most of the area west of 110W. Maximum seas of 14 ft are near 30N124W. These seas will slowly subside through Thu night. An extensive set of northwest swell, bringing maximum seas up to around 19 or 20 ft over the northern waters west of 125W, is forecast by the Wave models to arrive beginning early on Thu. The swell will gradually subside through Sat as it propagates southeastward. Farther to the southeast, a 1009 mb low is centered at 06N105W, with scattered moderate convection within 120 nm of the low in the north quadrant. A tight gradient north and northeast of the low is allowing for fresh to strong east winds to exist from 06N to 10N between 103W and 108W along with seas of 9-12 ft. The low is being energized by its proximity to the base of a negatively tilted mid-upper trough that extends well into the central deep tropics. The low is forecast to continue to move westward, reaching to near 110W by early Wed evening with strong east to southeast winds within 90 nm to its east and strong northeast to east winds within 120 nm to its west along with seas of 9-12 ft. The low is forecast to then weaken to a trough on Thu as it continues westward away from the mid to upper-level trough, but will remain along the southern periphery of high pressure that will be present across the area. The pressure gradient between the trough and the high pressure should maintain a rather large area of fresh to strong northeast trades and seas of 9-13 ft seas primarily from northwest swell over the central and western sections of the area by the end of the week and into the upcoming weekend. $$ Aguirre