000 AXPZ20 KNHC 090914 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 914 UTC Thu Nov 9 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 0600 UTC surface analysis and satellite imagery through 0900 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning...High pressure is surging down eastern Mexico in advance of a cold front currently located over the NW and W central Gulf of Mexico. Meanwhile, nocturnal drainage flow is helping to support fresh to strong northerly flow in the Gulf of Tehuantepec. Winds will increase to minimal gale force by this afternoon as the front draws closer and as the pressure gradient continues to tighten. Winds will then continue to pulse to gale force, occasionally strong gale during the overnight hours, through early next week. Winds may briefly diminish just below gale force during the afternoon hours after today. Seas will build to 10 to 14 ft during the strongest winds. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 10N83W to 09N100W to low pressure near 10N125W to 09N140W. Scattered moderate and isolated strong convection is from 06N to 10N between 82W and 86W, from 07N to 10N between 93W and 96W, from 07N to 11N between 102W and 108W, from 06N to 08N between 111W and 116W, and also within 90 nm to 180 nm N of the axis between 119W and 131W. Scattered moderate and isolated strong convection is within 180 nm W of a trough axis which extends from 18N133W to 14N136W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features section for information on a Gulf of Tehuantepec Gale Warning. A ridge will dominate the waters W of Baja California through the rest of the week, while a trough will meander between the coast of NW Mexico and the Gulf of California. Moderate to locally fresh NW to N flow will prevail across the waters W of Baja California, increasing to fresh to locally strong offshore of the northern waters this evening through Fri. A cold front is expected to weaken before reaching the area on Fri, but the associated long period NW swell inducing seas in the range of 8 to 10 ft will propagate southeastward across the waters N of 23N and to the W of Baja California on Fri, then spread southward through all of the waters W of Baja on Sat, subsiding to less than 8 ft by early Sun. The pressure gradient W of Baja California Norte will tighten Mon with winds increasing to fresh to strong, building fresh seas to 8 to 9 ft for the start of next week. Gulf of California: A relatively tight pressure gradient is supporting moderate to fresh NW flow across the central and southern Gulf, with gentle to moderate NW flow to the N. Seas are 2 ft or less in the northern Gulf, and 4 to 6 ft elsewhere. The gradient will slacken with winds diminishing to light to gentle throughout for the end of the week through Sat, with seas subsiding to 2 ft or less, except 4 to 6 ft near the entrance. The gradient will tighten back a bit for the end of the weekend into early next week with mainly moderate NW flow returning. Elsewhere, mainly gentle to moderate NW flow and 4 to 6 ft seas will prevail for the next several days. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Nocturnal drainage flow will support pulsing moderate to fresh winds during the overnight hours for the next several days, with seas occasionally building to 5 or 6 ft downstream of the Gulf near 11N87W. Light and variable winds and 4 to 6 ft seas are expected elsewhere to the N of 09N, while moderate to locally fresh southerly winds and 5 to 7 ft seas are forecast S of 09N through the next several days. REMAINDER OF THE AREA... A 1019 mb high pressure area is centered near 26N132W with a ridge axis extending from NE through SW of the high. A cold front extends from 30N132W to 27N140W. Associated winds are 20 kt or less over the discussion waters, but NW swell of 8 to 9 ft lagging behind the front is beginning to arrive. The front will weaken and eventually stall from 30N126W to 27N136W Fri, dissipating by early Sat before moving back W as a remnant trough. The NW swell will propagate out ahead of the boundary with seas quickly building to 13 ft near 30N139W by this early afternoon. The swell will then continue to propagate SE through the northern forecast waters while decaying. Seas of 8 ft or greater will cover the waters N of 15N W of 115W by Fri evening, then begin to subside to near 8 ft throughout the waters by Sun evening. A couple of transient and weak low pressure areas along the monsoon trough W of 120W will continue westward through the upcoming weekend and into early next week. Model guidance indicates a tightening pressure gradient during the weekend into early next week between the lows and building high pressure to the N. This may allow for trades to increase to fresh to strong across the waters S of 20N and N of the monsoon trough/ITCZ, supporting fresh seas of 8 to 9 ft. $$ Lewitsky