000 AXPZ20 KNHC 121602 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Tue Feb 12 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 1200 UTC surface analysis and satellite imagery through 1545 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: A cold front analyzed over the NW Gulf of Mexico this morning at 12Z will move across the western Gulf of Mexico, reaching the Bay of Campeche by early this evening. Strong high pressure will build southward over eastern Mexico in the wake of this front, with the resulting tight pressure gradient over southeastern Mexico leading to a surge of northerly winds that will funnel through the Chivela pass and out across the Gulf of Tehuantepec. This will bring next gap wind event across the Tehuantepec region. Gale conditions are expected to begin late tonight, and continue through Wed night before diminishing below gale force as high pressure over the Gulf of Mexico weakens as it shifts eastward. Winds will further diminish to 20 kt or less Thu. Per Wave model guidance, seas associated with this upcoming event are expected to peak near 18 or 19 ft on Wed. Eastern North Pacific Gale Warning: High pressure anchored by a 1022 mb high pressure system centered to the north of the area over California near 38N121W covers the northern forecast waters to the north of 20N and east of about 125W. The very tight pressure gradient between this area of high pressure and a low pressure system of 995 mb located to the west of the discussion area near 28N145W is supporting strong to near gale force southerly winds over much of the forecast waters N of 20N and W of 130W. The low pressure center will approach the forecast waters today while continuing to deepen. This will tighten the pressure gradient allowing for gale force winds to develop today N of 22N between 130W and 135W, and spreading slowly eastward through this evening. The low pressure is forecast to move across the far northwestern waters tonight, with associated cold front ushering in a brief period of gale force winds on either side of the front overnight. The area of high pressure will gradually weaken over the next 24 hours. This process will break down the pressure gradient enough to allow for winds to diminish below gale force by Wed morning. The cold front will usher in a fresh set of long-period northwest swell, with seas peaking near 18 ft late tonight through Wed before they begin to slowly subside. Please read the latest High Seas Forecast issued by the National Hurricane Center under AWIPS/WMO headers FZPN03/HSFEP2, or at the website https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for more details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough axis extends from a 1009 mb low over northwestern Colombia to the coast at 06N77W and to 05N87W, where latest scatterometer data indicated that the ITCZ begins and continues to 02N98W to 03N110W to 04N120W to 04N130W and to beyond 08N140W. Scattered moderate convection is noted within 30 nm either side of the ITCZ between 90W and 96W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see above for more on the upcoming gale force gap wind event in the Gulf of Tehuantepec. Gulf of California: An overnight Ascat pass revealed fresh to strong northwest winds across the Gulf from 24N to 29N. These winds will diminish to mainly fresh by early this afternoon as strong high pressure over the Gulf of Mexico weakens while it slides eastward. The gradient associated with high pressure over these waters is bringing gentle to moderate northwest to north winds to these waters, with seas of 8 to 10 ft in northwest swell. Winds will diminish to light and variable late this afternoon or early this evening. Elsewhere, light to gentle breezes and seas in the 4 to 6 ft range will prevail between the Gulf of Tehuantepec and Cabo Corrientes through the forecast period. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Fresh to locally strong northeast to east winds across the Gulf of Papagayo and reaching west to near 89W will diminish to mainly fresh winds early this afternoon, with little change through early on Wed. These winds will then re- develop from 10N to 11N between 86W and 88W by late Wed night and continue through early Thu afternoon. Winds will be greatest during the overnight and early morning hours with the assistance of the nocturnal drainage flow. Gulf of Panama: Gentle to moderate north winds will continue over the Gulf of Panama through the end of the week. Light to gentle breezes will persist elsewhere through Fri. REMAINDER OF THE AREA... Please see above for more on the upcoming gale force winds over portions of the discussion waters N of 22N and W of 125W. Elsewhere, long-period northwest swell continues across the forecast waters, mixing with long-period cross equatorial southwest well. Seas of 8 ft or greater will dominate most of the waters W of 115W, with another area of 8 to 9 ft seas covering much of the waters S of 10N between 100W and 115W today before areal coverage of seas greater than 8 ft decreases. Satellite imagery shows ample deep layer moisture in the form of mostly mid and upper-level clouds north of about 18N streaming northeastward in strong southwest mid and upper-level flow. This flow is located ahead of a large cyclonic vortex located west of 140W near 28N152W, that supports the 995 mb low pressure system as mentioned above under the Special Features section. Areas of rain along with embedded showers are possible underneath these clouds, and are expected to last through the end of the week. $$ Aguirre