000 AXPZ20 KNHC 131543 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Mon Nov 13 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 1500 UTC. ...SPECIAL FEATURES... A 1007 mb low pressure is located near 17.5N127W moving NNW at 11 kt. Latest scatterometer data indicated winds of 20 to 30 kt within about 120 nm of low center, except in the SW quadrant. This system has become less organized, and convection is limited at this time. Environmental conditions are currently marginally conducive for development, and are forecast to become quite unfavorable for tropical cyclone formation to occur on Tuesday. This system is expected to move west-northwestward at 10 to 15 kt across the open eastern Pacific waters during the next few days. An area of fresh to strong NE to E winds is forecast to persist on the northern semicircle of the low center due to the pressure gradient between the low and a high pressure located to the N. Please refer to the East Pacific Tropical Weather Outlook for more details. A gale warning remains in effect for the Gulf of Tehuantepec. A ship call sign A8JE6 located near 13.5N96W is currently reporting N winds of 33 kt. A ridge along the eastern slopes of the Sierra Madre Mountains combined with low pressure in the SW Caribbean is maintaining a tight pressure gradient across the Isthmus of Tehuantepec. Model guidance suggests that the current synoptic pattern will remain favorable for very strong gap wind flow through early Wed morning, with peak winds between 35 and 40 kt through early Tue morning. Max sea heights will be 12 to 16 feet, then subside slowly Tue. Winds are forecast to diminish below gale force by early Wed afternoon as the ridge weakens some. Northerly winds in the 20 to 30 kt range will continue to blow across the Tehuantepec region through Fri. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 10N84W to 07N100W to 10N120W to 13N127W to 12N140W. Scattered moderate isolated strong convection is from 04N to 08N E of 78W to the coast of Colombia. Similar convection is from 07N to 09N between 109W and 113W. Scattered moderate convection is from 06N to 08N between 93W and 98W, and from 09N to 14N W of 138W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please refer to the Special Features section for information regarding the ongoing Gulf of Tehuantepec gale warning. A ridge will dominate the waters W of Baja California the next several days. The pressure gradient W of Baja California will tighten slightly today and Tue as high pressure shifts closer to the coast, resulting in fresh to locally strong NW winds N of 28N between 116W and 120W by early Tue morning, with seas building to 8 ft. Gentle to moderate NW winds are expected to persist across the Gulf of California. Elsewhere, mainly light to gentle winds and seas of 4 to 5 ft will prevail through Wed night. A weakening cold front will move across the northern Baja California peninsula on Fri. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Light and variable winds and seas of 4 to 6 ft are expected N of the monsoon trough, which will fluctuate between 07N and 10N through Wed. Moderate to locally fresh S to SW winds and seas of 5 to 7 ft are forecast S of the monsoon trough through Tuesday. Stronger SW winds south of the monsoon trough will build seas to above 8 ft in the Gulf of Panama region Tuesday through Thursday. REMAINDER OF THE AREA... Low pressure centered near 17.5N127W is discussed above in Special Features section. The combination of decaying long period swell in N waters and strong winds north of the low is maintaining an area of seas greater than 8 ft from 12N to 21N between 123W and 136W. These sea heights will diminish through Tue as the swell continues to decay and the low weakens in a hostile environment. A fresh set of 8 to 9 ft NW swell, with moderate to fresh southerly winds will dominate the NW waters tonight and Tuesday, ahead of a developing low pressure located west of area. The low pressure will move NE and the associated cold front will enter the far NW corner of the forecast area early on Wed. Fresh winds and seas of 8 to 9 ft will follow the front forecast to reach from 30N133W to 26N140W by Wed night. $$ GR