000 AXPZ20 KNHC 311534 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Tue Oct 31 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 1200 UTC surface analysis and satellite imagery through 1515 UTC. INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 10N85W to low pressure near 11N96W to 1010 mb to 12N105W 1009 mb to 12N117W to low pressure near 11N123W 1009 mb to 10N132W. ITCZ extends from 10N132W to beyond 09N140W. Scattered moderate isolated strong convection exists from 12N-15N between 117W-121W, and also within 30 nm of the axis between 110W-115W and between 115W-117W. Scattered moderate convection is within 120 nm N of the axis W of 136W, and within 60 nm S of the axis between 123W-125W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... The significant swell event affecting the coast of Baja California the past few days continues to decay, with seas subsiding to 6-8 ft. Seas will subside to the range of 4-6 ft this afternoon. The pressure gradient associated with a weak ridge extending into the offshore waters of Baja California will produce light to gentle NW winds through Friday. The next gap wind event through isthmus of Tehuantepec region is forecast beginning on Friday night, with strong northerly winds expected to surge out across the Gulf of Tehuantepec as high pressure slides eastward across the northern Gulf of Mexico. Presently, the model guidance indicates that these winds may reach to near gale force on Saturday, but may easily attain minimal gale force during Saturday or Saturday night with just a slight tightening of the pressure gradient that will develop over southeastern Mexico. Wave model guidance shows seas building up to around 11 or 12 ft. Stay tuned for future forecasts that will include details on this upcoming gap wind event. Gulf of California: The 0430 UTC ASCAT pass from last night showed moderate to fresh W-SW winds in the northern Gulf between 29N-31N. Little change is expected in northern waters today. Gentle to moderate winds are expected across the remainder of the gulf through Saturday. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Latest scatterometer data indicates gentle to moderate winds S of the monsoon trough, and light winds elsewhere. Seas generally are between 4-6 ft. Little change in winds and seas is expected through Friday. REMAINDER OF THE AREA... The NW swell event from the past few days continues to propagate through the forecast waters west of about 97W, supporting seas of 7-10 ft. As the swell energy decays into Thursday, expect for these seas to subside to 6-8 ft at that time. A weak cold front is forecast to reach the NW corner of the forecast area on Wednesday night, then move slowly southeastward through Friday with little impact in winds and seas. Global model guidance suggests that broad strong high pressure will build southeastward over the NW waters Friday night and Saturday, pushing the front eastward. At that time, guidance is consistently depicting fresh to strong winds northerly winds behind the front and building seas of 12-14 ft in long period NW swell. In the tropics, a series of weak low pressure systems will linger along the monsoon trough region as mentioned above. Although tropical cyclone formation is not expected through the end of the week with any of the lows, the western most one analyzed near 11N123W is forecast to move in a generally northwesterly direction through Friday before weakening to a trough late Friday and Saturday. Prior to it weakening, however, scattered showers and thunderstorms with gusty winds are possible within the immediate vicinity of the low as well as to within about 180 nm to its E as it will be under a favorable diffluent flow pattern aloft associated with a mid to upper level trough to its W. $$ Aguirre