000 AXPZ20 KNHC 202148 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Sun Nov 20 2016 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 1800 UTC surface analysis and satellite imagery through 2145 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec gale warning: Currently there are gale force winds of 30 to 40 kt with maximum seas of 23 ft downstream of the Gulf of Tehuantepec near 14N96W. High profile vessels should expect minimal storm force winds at 30 meters tonight. Gale conditions will end on Mon morning with near gale force conditions continuing through sunrise on Tue, then diminishing briefly to 20 kt or less on Tue afternoon. Strong n winds resume again on Tue evening and gradually strengthen Tue night and Wed to minimal gale force on again on Wed night. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends w off the Pacific coast of northern Panama at 08N83W to 07N103W where scatterometer winds indicate an ITCZ forms and extends sw to 07N106W, the turns nw to 09N112W, then sw to 08N118W, then nw again through an embedded 1010 mb low pres at 09N127W, then the ITCZ continues sw to beyond 08N140W. Scattered moderate isolated strong convection is observed within 90 nm either side of a line from 08N83W to 06N96W, within 30 nm either side of a line from 09N97W to 07N107W to 10N116W to 09N130W, and within 60 nm of 06.5N115W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See special features section for a gale warning in the Gulf of Tehuantepec. A weakening cold front will sweep e across the waters n of 26N tonight and early Mon accompanied by a 10-15 kt sw to w to nw wind shift, with the nw post-frontal flow increasing to a fresh breeze on Mon and Mon night, and spreading se across all waters w of Baja on Mon night. Large nw swell, in the form of 7 to 11 ft seas, have already reached the n coast of the Baja Peninsula, and these seas are expected to spread se across all the offshore waters w of the Baja Peninsula by Mon night, then subside from the n throughout the day on Tue to less than 8 ft on Wed morning. Moderate to locally fresh s to sw winds have set up across the northern Gulf of California ahead of the cold front. Expect these southerly winds to increase to strong to near gale force tonight through Mon with seas building to 7 ft in the areas of longest fetch. The winds will clock to the nw behind the front on Mon evening but diminish to moderate to a locally fresh breeze, with these conditions spreading se across the entire Gulf of California on Tue. Latest guidance suggests that embedded patches of strong nw flow will develop across the central gulf waters on Tue night and Wed, with a reinforcing northerly surge on Wed night producing fresh to strong nw flow across the entire gulf waters and continuing through Thu night. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Fonseca: a narrow and brief pulse of strong nne winds expected tonight. Gulf of Papagayo: strong to near gale force ne winds will pulse develop across and also extend sw from the Gulf of Papagayo tonight through Tue morning in association with a tropical low pressure in the SW Caribbean, with seas building to about 9 ft 10N88W. Gulf of Panama: Guidance is suggesting that the southwesterly flow will increase briefly to a strong breeze on Mon night. Gentle to locally moderate n winds and combined seas of 3 to 6 ft are occurring elsewhere n of the monsoon trough which continues to meander e to w between 07N and 09N, while moderate to fresh sw flow is observed s of the monsoon trough with combined seas of 4 to 7 ft in long-period sw swell. Little change forecast through early next week. Mariners planning to transit through the Panama Canal are urged to monitor the broad area of low pressure in the sw Caribbean that has the potential to become a tropical cyclone. REMAINDER OF THE AREA... A cold front along 32N121W to 20N140W will weaken as it crosses the northern Baja Peninsula late tonight into Mon. Large nw swell will follow the front with seas of 8 of 17 ft initially with the highest seas between 30N and 32N, but subsiding to 7 to 11 ft by the time they reach the northern Baja Peninsula tonight. The post frontal high pressure will result in strong ne trades across the tropics n of the ITCZ and w of 125W through the middle of next week. $$ Nelson