000 AXPZ20 KNHC 140939 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 938 UTC Mon Jan 14 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 0900 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning...High pressure building N of the region behind a cold front moving across the northwestern Gulf of Mexico is supporting strong to minimal gale force winds across the Gulf of Tehuantepec this morning. A scatterometer satellite pass from 04 UTC indicated 35 kt in the Gulf of Tehuantepec. These northerly winds are expected to further increase to 35-40 kt through the morning. This gale force wind event is forecast to continue through Tue night. Strong northerly gap winds will then continue to pulse each night through Thu night, then gradually diminish as the high pressure weakens and shifts east of the Gulf. Peak seas will build as high as 15-16 ft this morning in the area of gale force winds, with NE swell in excess of 8 ft propagating as far as 105W by early Tue morning. This swell will merge with longer period NW and SW swell through early next week. For more information, see the East Pacific High Seas Forecast under WMO/AWIPS headers FZNT02 KNHC/HSFAT2. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough extends from 04N78W to 07N89W to 05N100W. The ITCZ continues from 05N100W 07N115W to beyond 05N140W. Scattered moderate convection is noted from 06N to 09N between 115W and 125W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... An old and weakening cold front stalled today NE to SW across the northern Gulf of California and central portions of Baja California and is becoming diffuse. This is producing gentle winds across the waters NW of this old boundary, and light to moderate winds SE of the boundary to 21N. Long period NW swell of 8 to 10 ft accompanying the front will move throughout the offshore waters of Baja California and the western Revillagigedo Islands through tonight, then subside below 8 ft from north to south through Mon, just as another weakening cold front approaching from the west delivers a new round of large NW swell. The reinforcing push of NW swell will cross most of the open offshore waters of Baja California and the Revillagigedo Islands to reach as far south as the coastal waters of Cabo Corrientes through mid week. Looking ahead, high pressure will build off the west coast of Baja California late this week, allowing fresh to strong northerly winds across the offshore waters north of Cabo San Lazaro. Gulf of California: Weak high pressure centered in the easten Pacific off Punta Eugenia will maintain gentle flow across the Gulf of California into Mon. The high will weaken and shift east ahead of an approaching deep layer trough related to the cold front west of the area. This will briefly tighten the pressure gradient over the southern Gulf late Mon, allowing northerly fresh to strong winds between Los Cabos and Cabo Corrientes. Winds will diminish Mon night as the high pressure dissipates. Looking ahead, fresh northerly winds will return to the southern Gulf by late Thu as high pressure again builds off the west coast of Baja California. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Strong NE to E winds will prevail across the Gulf region. The strongest winds and greatest areal coverage downstream of the Gulf of Papagayo will be each night as nocturnal drainage flow augments the winds. Seas are forecast to build to 8-10 ft by early Tue morning. Gulf of Panama: Moderate to fresh northerly winds will flow downstream to near 05N with pulse to 20 to 25 kt mainly in the southwest Gulf off the Azuero Peninsula. Accompanying seas will reach 6-8 ft. REMAINDER OF THE AREA... Fresh NW winds and large, long-period NW swell prevail behind a cold front moving eastward across the waters north of 26N, with front extending from 30N124W to 25N132W. Fresh to strong winds follow the front, and recent altimeter satellite passes indicate 10 to 15 ft seas in the wake of the front. High pressure building in the wake of the front is supporting an area of fresh to strong trade winds farther south into the deep tropics, particularly from 05N to 11N west of 135W, with 10-12 ft seas in mixed NW swell and NE windwaves. Divergence aloft east of a deep layer trough along 125W north of 15N is supporting an area of showers and thunderstorms along the ITCZ between 115W and 125W, as well as a small area of numerous strong thunderstorms around 90 nm southwest of Clarion Island. Clusters of showers and thunderstorms will persist through today then diminish tonight as the trough dampens out. Another cold front will follow on the heels of the first two front and traverse the waters north of 25N late today through Wed and generate continued pulses of strong W winds and swell in excess of 12 ft. This will erode the high pressure behind the current front, allowing trade wind flow to diminish accordingly. Looking ahead, the front will become stationary and dissipates during the mid to late week, as a ridge builds along 25N/26N. This will allow fresh trade winds to re-establish farther south across the deep tropics. Global guidance is in decent agreement showing the development of a trough or weak low pressure area forming along the ITCZ in the eastern Pacific over the next couple of days, related to the interaction of the gap wind flow with a negatively tilted mid to upper trough reaching deep into the tropics. The gradient between this surface feature and the developing ridge by mid to late week will support an area of strong winds and seas at least to 8 ft within 120 nm on the north side of the low/trough as it moves westward, reaching 110W by late Thu. Through Fri, the low/trough moves west of its upper support and starts to weaken, allowing winds and seas to diminish. $$ Christensen