000 AXPZ20 KNHC 120305 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 059 UTC Sun Nov 12 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 0230 UTC. ...SPECIAL FEATURES... ...A GALE WARNING FOR THE GULF OF TEHUANTEPEC... Gale-force winds continue over the Gulf of Tehuantepec. A high pressure ridge along the Sierra Madre Oriental is maintaining a tight pressure gradient over the Isthmus of Tehuantepec. Model guidance suggests that the current synoptic pattern will remain favorable for gale force northerly gap wind flow through Tue night. Wind speeds will peak between 35 and 40 kt Sunday night through Mon night. Sea heights will range from 10 feet to 13 feet in the current conditions. Sea heights could build to 17 feet on Tuesday due to the long event duration and sustained wind speeds. The leading edge of the resultant 8 foot seas, propagating away from the source region, is forecast to reach 06N102W on Tuesday. Winds could remain at or above gale force through Wed. High pres over the western Gulf should weaken and shift east on Thursday, allowing winds over the Gulf of Tehuantepec to finally subside. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough stretches from Costa Rica near 09N83W to 07N89W to 07N98W to 07N105W to 1008 mb low pressure centered near 11N120W to 12N132W to 10N140W. Scattered moderate and isolated strong convection is present from 09N to 15N between 116W and 137W. ...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 during the next several days, while a trough will meander along the coast of NW Mexico and over the Gulf of California. Moderate to fresh N to NW winds will prevail over the waters W of Baja California through Tuesday night and the pressure gradient W of Baja California will tighten slightly Sun night and Mon as high pressure shifts eastward closer to the coast. Expect fresh to locally strong NW winds N of 25N and E of 119W from early Monday to early Wednesday, with seas building to 8 ft on Wednesday in response to NW swell. Long period NW swell propagating SE across the waters W of Baja California are slowly decaying. This will allow seas W of Baja to subside from between 6 and 9 ft tonight to between 5 and 7 ft on Monday and slowly subside through Sunday. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Light and variable winds, and seas of 4-6 ft, are generally expected N of 09N. Moderate to locally fresh S to SW winds and seas of 5 to 7 ft are forecast S of 09N through Tuesday. Seas in the Gulf of panama could build to 8 ft or above on Tuesday night in response to a surge of monsoonal winds. REMAINDER OF THE AREA... Long period NW swell propagating southeastward are maintaining seas at or above 8 ft N generally from 10N to 25N W of 113W. Seas in most of this area will subside below 8 ft by Mon morning as the swell decay. Another round of NW swell generated by a cold front to the N of the discussion area could reach the NW corner of the discussion area on Mon night, but the coverage of 8 ft seas is expected to be small as this event looks relatively weak. A 1008 mb surface low is centered near 11N120W. Consensus global model guidance indicates that this low center should move WNW then NW through Tuesday. The guidance indicates the pressure gradient between this low and high pressure to the north will create a swath of 20 to 30 kt winds within 240 of the low on Sun, with associated seas building to between 9 and 13 ft by Sunday afternoon, then to 17 feet by Monday afternoon. Gradual development of this system is possible before upper-level winds become unfavorable for development by the middle of next week. $$ CAM