000 AXPZ20 KNHC 270351 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Mon Nov 27 2017 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 0330 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: A tight pressure gradient has become established across southern Mexico between a building high pressure over the western Gulf of Mexico and relatively lower pressure over the deep tropics. The strong gap northerly winds in the Gulf of Tehuantepec have increased significantly to a strong gale with N-NE winds of 30-40 kt and seas in the range of 12 to 16 ft. The strong gale winds will slowly diminish to 30-35 kt on Monday afternoon, with seas subsiding to 10-14 ft. Swell from the gap wind event with 8 ft or greater will reach more than 500 nm offshore of the Gulf of Tehuantepec by late on Monday. The high pressure will weaken and shift eastward on Tuesday, allowing for the gale force winds to diminish. Another round of gale force winds is expected Wed and Thu. INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 09N84W to 08N91W to 09N98W to 09N107W, where scatterometer data indicates that the ITCZ axis and continues to 10N115W where it briefly ends. It resumes at 09N131W to beyond 09N140W. Scattered moderate isolated strong convection is within 60 nm of the axis between 97W-103W, and also between 103W-106W. Scattered moderate convection is within 60 nm N of the axis between 92W and 94W, and also within 60 nm of S of the axis between 104W-107W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See Special Features paragraph above for information on the Gulf of Tehuantepec Gale Warning. A 1020 mb high pressure centered near 27N126W will maintain gentle to moderate breezes and slight seas into Monday, ahead of a cold front approaching the area from the west. The front will cross the offshore areas off Baja California Monday and the northern Gulf of California on Tuesday. NW winds will increase to fresh to strong off Baja California Norte in the wake of the front Monday and Monday night. Seas will build to 8 to 12 ft in NW swell, with 8 ft swell reaching as far S as the Revillagigedo Islands by Tuesday night. Fresh to strong NW flow will also follow the front in the northern Gulf of California Monday night into Tuesday, with seas building to the range of 4 to 6 ft. Winds will diminish Tuesday into Wednesday as the front stalls and dissipates, but seas greater than 8 ft will persist in open waters through late week as another round of reinforcing swell moves into the region. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Expect a typical nocturnal maximum of around 25 kt across the region through early Tueday morning, diminishing to 15 to 20 kt by mid afternoon. Seas will build to a maximize of around 7 ft each morning near sunrise, and will likely build locally to 8 ft early Monday morning, with a more extensive area of 8 ft seas expected Tuesday morning. Moderate to locally fresh NE winds are expected across the Gulf of Fonseca each night through Tuesday. Light to gentle N to NE winds, and 3 to 5 ft seas are expected elsewhere through early Mon to the N of the monsoon trough which has been meandering between 09N and 11N. Moderate southerly winds, and 4 to 6 ft seas, are forecast S of the monsoon trough. Northerly swell generated in the Gulf of Tehuantepec will reach the western part of forecast zone PMZ111 (offshore waters of Guatemala and El Salvador) building seas up to 11 or 12 ft late tonight through Monday night. REMAINDER OF THE AREA... A cold front is analyzed from near 32N125W to near 22N135W, where it becomes a dissipationg front to 19N140W. Ship observations and ASCAT data from Sunday afternoon indicated fresh to strong NW winds in the wake of the front. The ship observation along with a recent altimeter satellite pass farther upstream indicated seas of 8 to 12 ft west of the front. An area of 8 to 11 ft seas due to a NW swell will persist to the S of 14N W of 125W. These seas will propagate southward across the equator while decaying through early Monday, just ahead of the reinforcing NW swell currently entering the forecast area. $$ Aguirre