000 AXPZ20 KNHC 271554 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 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 1200 UTC surface analysis and satellite imagery through 1400 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: Gale force northerly winds across the Gulf of Tehuantepec overnight have diminished to 20- 30 kt this morning, as the associated pressure gradient across southeast Mexico has begun to weaken. Resultant wave heights from these winds remained in the 8-11 ft range. This gap wind event will begin to shut down this afternoon, and wave heights will lower to 8-9 ft in merging north and southwest swell reaching as far downstream as 12N96W. Winds will diminish to around 10 kt and wave heights lower to less than 8 ft early this evening. Variable winds at less than 20 kt will then prevail across the Tehuantepec region through the first part of the week. Please refer to the East Pacific High Seas Forecast issued by the National Hurricane center under AWIPS/WMO headers FZPN03 KNHC/HSFEP2 or at the website https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for more specific marine details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A trough extends from a 1010 mb low over northern Colombia near 09.5N74W to 02.5N80W TO 05N87W, where it transitions to the ITCZ and continues to 07N108W TO 04N120W to beyond the area at 04N140W. Scattered moderate to strong convection is noted from 03N to 07.5N to the east of 79W, from 03N to 07N between 90W and 110W, and from 06.5N to 10N between 110W and 127W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Relatively weak high pressure remains over the offshore waters, centered on a 1018 mb high near 27N122W. The associated pressure gradient is maintaining gentle to moderate northwest to north winds over the forecast waters. Seas are in the 4 to 6 ft range. With the exception of winds briefly becoming fresh along and just offshore the central part of the Baja California Peninsula this afternoon, expect near steady state conditions through Sun night. Fresh N swell is forecast to cross 32N and affect the northern offshore waters on Mon bringing seas of 5 to 7 ft there through Tue night, before subsiding slightly. Moderate NW winds are expected across these offshore waters through Tue. Elsewhere, light to gentle northwest to north winds are present across the waters from Las Tres Marias to Puerto Angel, with seas of 4 to 5 ft in mixed swell. These winds will shift to northwest to west in direction this afternoon through early next week. Gulf of California: Fresh to strong southwest winds will develop over the northern Gulf of California tonight through Mon night as a weak trough approaches, and gradually build seas to 4-6 ft by Mon. These winds diminish to fresh winds early Tue and become light to gentle south to southwest winds Tue afternoon. Gulf of Tehuantepec: See above for details regarding the end of the short-lived and late season gale event. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Moderate to fresh northeast 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 ft range by south to southwest swell arriving from the Southern Hemisphere. Wave heights between Ecuador and the Galapagos Islands are in the 5 to 7 ft range from south to southwest swell based on latest altimeter data in this region. Long-period south to southwest swell will maintain seas between 5 and 7 ft for the offshore waters west of Ecuador through Wed night. Satellite imagery this morning confirms some of the overnight weather observations along the Central American coasts. Ongoing agricultural fires from the past few days across southeastern Mexico and Central American have been transported southwestward across the Pacific offshore waters, and can be seen in satellite imagery from the Gulf of Tehuantepec to well offshore of the Gulf of Papagayo to 09N89W. Observations suggest visibilities are reduced to the 3-5 nm range. This smoke may take several days to clear the region as fires continue and moderate NE low level winds prevail across the region. REMAINDER OF THE AREA... Moderate northeast to east trades are generally present over the waters from 07N to 19N and W of 118W. Altimeter data from last night across this area suggested 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 remaining in the 6 to 8 ft range. An upper-level low is moving eastward across the northwest portion of the discussion, while at the surface a weakening and stationary low pressure center of 1016 mb is analyzed near 28N135W, with a trough extending from the low to west of the area at 27N140W. The upper low is producing widely scattered showers and isolated thunderstorms north of 28N and between 129W and 133W. The surface low is forecast to move slowly eastward along 28-29N while dragging the trough over the northern waters through tonight. Winds in the vicinity of the low are expected to remain less than 20 kt with seas 6 to 7 ft across the far northwest waters. To the east and southeast of the low to 125W expect variable winds generally less than 15 kt and seas around 5 ft building to 5 to 7 ft in north swell tonight through Mon. Higher seas, likely to peak at 8 or 9 ft, are forecast to move into the north-central waters north of 28N on Mon as fresh north swell propagates through those waters. Cross-equatorial southwest swell in the far southern waters 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 01N and west of 95W. $$ Stripling