000 AXPZ20 KNHC 220946 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Sat Apr 22 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 0945 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough extends w from 08N83W TO 05N90W with isolated moderate to strong convection observed along the trough within 120 nm either side of line from 05N83W to 07N105W. Scatterometer winds indicate that the ITCZ forms at 05N90W and extends w to 07N116W to beyond 04N140W. Scattered moderate isolated strong convection is noted along the ITCZ within 150 nm either side of a line 05N114W to 07N135W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A surface ridge extends from nw to se across the offshore waters to the w of 100W. Gentle to locally moderate northwesterly winds are observed across the waters n of 25N, with 7 to 10 ft seas primarily due to long period nw swell. The swells should subside later today, with seas of 5 to 7 ft tonight, except to the n of 30N where fresh to locally strong breezes are forecast to develop accompanied by 8 to 11 ft seas. These seas should arrive at 29N120W on Sun, and spread s across the waters n of 24N by late Mon night before beginning to subside. However, a tightening pressure gradient will produce strong nw winds again, generally across the waters n of 29N e of 121w on Tue, and send another batch of large seas s across the waters n of 23N late in the week. Combined seas of 12 to 16 ft are expected from 27N to 32N on Thu night. Gulf of California: A light to gentle nw breeze forecast for today. Variable winds will set up around a surface low developing n of 30N late tonight, where it will meander through at least the middle of next week with a trough extending s across the Baja California Peninsula. Fresh to strong nocturnal sw winds are expected each night across the gulf waters from 29.5N to 30.5N, with seas building to about 5 ft. Gulf of Tehuantepec: Moderate northerly drainage flow expected at sunrise this morning and again on Sun morning. Model guidance has backed off on the strength of post-frontal ridging across the sw Gulf of Mexico. Now expect strong northerly drainage flow to develop across the Gulf of Tehuantepec on Sun evening and rapidly increase to near gale force late Sun night, with seas building to 11 ft downstream of the gulf near 14.5N95W around sunrise on Mon. The pressure gradient will quickly relax on Mon with winds less than 20 kt and seas less than 8 ft on Mon night. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Light to gentle winds mostly onshore flow expected during the day becoming offshore along the coasts at night. Combined seas of 3 to 5 ft in mixed SW and NW swell forecast during the next several days. REMAINDER OF THE AREA... A surface ridge along about 130W continues to block the eastern advance of cold fronts. A cold front currently along 32N132W to 26N140W will stall this evening and dissipate tonight. Large nw swell will build seas of 8 to 13 ft behind the front today. Expect the nw swell, in the form of 8 to 10 ft seas, to propagate e reaching from the northern Baja Peninsula to 07N140W late Sun, and then subsiding from the nw early next week. Strong nw winds expected n of 29.5N e of 123W on Sun night through early Wed, with the pressure gradient further strengthening late next week to the ne of a ridge from 32N136w to 11N110W. $$ Nelson