000 AXPZ20 KNHC 270228 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Sat Apr 27 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 0200 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: Strong north winds began to spill across the Gulf of Tehuantepec late this morning, behind a stalled cold front across the central Bay of Campeche. Winds have gradually increased this afternoon and evening to near 30 kt this evening and will reach near minimal gale force during the next few hours and persist through around sunrise Sat as high pressure over SE Mexico and the western Gulf of Mexico builds across the region. Wave heights downstream of Tehuantepec have reached 8-9 ft this evening and will peak at 10-12 ft Sat morning before quickly subsiding to 8 ft around noon on Sat, then to less than 8 ft by Sat evening. Seas of 8 ft will propagate downstream from the Gulf to near 12N96W before subsiding Sat afternoon. Please refer to the East Pacific High Seas Forecast under AWIPS/WMO headers HSFEP2/FZPN03 KNHC for more specific marine details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A trough extends from a 1009 mb low over NW Colombia near 10N74W to 02.5N81W TO 05.5N88W, where it transitions to the ITCZ and continues to 08N112W TO 05N123W to beyond 07.5N140W. Widely scattered moderate isolated strong convection is present from 07N to 09.5N between 83W and 89W. Scattered moderate to strong convection is noted from 05.5N to 10.5N between 105W and 130W, and from 10.5N to 13N between 122W and 132W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Relatively weak high pressure lingers over the offshore waters, centered on a 1018 mb high near 27N124W. The associated pressure gradient is maintaining gentle to moderate NW to N winds over the forecast waters. Seas are in the 4-6 ft range. With the exception of winds briefly becoming fresh along and just offshore the central part of the Baja California Peninsula Sat afternoon, expect near steady state conditions through Sun night. New NW swell will cause combined seas in the far NW portion of the offshore waters to build only one foot higher Mon night and Tue. Light to gentle NW to W winds prevail this evening across the waters from Las Tres Marias to Puerto Angel, with seas of 4 to 5 ft in mixed swell. Winds are expected to become more NW to N tonight through Sat there in response to the developing Gulf of Tehuantepec gap wind event, before returning to NW to W winds Sun through early next week. Gulf of California: Fresh to strong SW gap winds will develop over the northern Gulf of California Sun night through Mon night as a weakening cold front approaches. S to SW winds will decrease to fresh on Tue. Seas will be 3 ft or less, with the exception of seas building to 4-7 ft in the far northern part on Mon. Gulf of Tehuantepec: See above for details regarding a short- lived, late season gale event forecast to begin tonight. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Moderate to fresh NE winds over the Gulf of Papagayo region will become strong Mon night through Tue night. Highest winds and seas will occur at night. Gulf of Panama: Moderate northerly winds will diminish to gentle Sat, then remain gentle through Tue night. Seas in this area will be maintained in the 3 to 5 foot range by S to SW swell arriving from the Southern Hemisphere.. Wave heights between Ecuador and the Galapagos Islands are currently running between 5 and 7 ft in S to SW swell based on latest altimeter data in this region. Long period S to SW swell will maintain seas between 5 and 7 feet for the offshore waters W of Ecuador through Tue night. REMAINDER OF THE AREA... Moderate NE to E trades are generally present over the waters from 06N to 17N and W of 115W as depicted by afternoon scatterometer data. The latest altimeter data across this area suggests that corresponding wave heights are in the 6 to 8 ft range. Rather weak high pressure over the northern waters will maintain moderate trades across the tradewind belt through early next week with seas in the 6 to 8 ft range. An upper level low pressure system moving eastward across the NW portion of the discussion area has carved out a weak 1013 mb low center at the surface near 29N136W, with a surface trough spiraling out of the low to 28N132W to 21N137W. The upper low is currently triggering moderate convection near the upper low, within 90 nm of 29.5N132.5W. The surface low will remain nearly stationary through tonight, then drift east along 29N while dragging the trough as a developing cold front over the northern waters Sat and Sat night. Winds in the vicinity of the low are expected to remain less than 20 kt with seas 6-7 ft across the far NW waters, briefly reaching 6-8 ft tonight. E and SE of the low to 125W expect variable winds generally less than 15 kt and seas around 5 ft building to 5-7 ft in N swell Sun night through Mon. SW swell from the Southern Hemisphere are arriving in the far southern waters and will spread northward across much of the forecast area east of 120W through this weekend. Seas to 8 ft will generally be confined to the waters south of the 03N and west of 95W. $$ Stripling