000 AXPZ20 KNHC 141605 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Fri Apr 14 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 1545 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The northern Intertropical Convergence Zone axis extends from 03N92W to 02N106W to 03.5N120W to 04N130W to 04N140W. Numerous moderate to strong convection is noted within 180 nm south and 60 nm north of the axis between 118W and 122W, within 120 nm north of the axis between 134W and 136W, and within 120 nm north and 60 nm south of the axis west 136W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A tight pressure gradient between high pressure over eastern Mexico and lower pressures south of the Tehuantepec region will support fresh to strong northerly winds across the Isthmus of Tehuantepec today through Saturday afternoon. A surface ridge extends into the offshore waters while surface low pressure continues along the Gulf of California and over the northwest section of Mexico. A tightened pressure gradient between these two features continue to support northwest fresh to strong winds offshore of Baja California Norte where seas are up to 8 ft. The surface trough is forecast to weaken by late this afternoon, which will allow for the pressure gradient to relax and winds to diminish to moderate to fresh category. Northwest swell, however, will continue to support seas up to 9 ft off the Baja California Norte through Saturday night. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... In the Gulf of Papagayo, fresh to locally strong drainage flow is expected to pulse at night Friday and Saturday. Seas are expected to build to 8 ft with these winds. In the Gulf of Panama, moderate to fresh northerly flow is expected during the overnight hours through the upcoming weekend. Seas will be in the range of 5 to 6 ft downstream of the Gulf. Elsewhere, light to gentle winds and combined seas of 3 to 6 ft will change little through the weekend. REMAINDER OF THE AREA... A large set of northwest swell producing seas of 8 to 11 ft is in the northwest and north-central portion of the basin, which will continue to spread east towards the offshore waters of Baja California Norte this afternoon. The next cold front is forecast to enter northwest waters Saturday afternoon, however south to southwest fresh to strong winds ahead of the front will enter the region during the morning hours. A new set of northwest swell associated with this front will build seas in the range of 8 to 10 ft in the far northwest portion of the area Saturday. Seas will subside Sunday morning as the swell energy decays. Surface ridging dominates the remainder of the area being anchored by a 1027 mb high pressure center analyzed north of the area near 35N130W. The pressure gradient between the ridge and lower pressures found to the southwest of the ridge is allowing for generally fresh to strong northeast winds from 05N to 14N west of 134W, with resultant seas of 9 to 10 ft as indicated by latest available altimeter data. The high pressure presently over the area will be forced eastward with the approach of deep layer troughing from the west and the associated aforementioned cold front. The cold front is forecast to approach the far northwest corner of the discussion early on Saturday. A tight pressure gradient ahead of the front will allow for strong southerly winds to develop to the north of 28N and west of 136W. By Saturday evening, the cold front is expected to reach from near 32N138W to 29N140W, with strong to near gale force southerly winds expected ahead of it to the north of 28N and east to near 133W. The front will quickly move across the northwest waters, and begin to weaken as it reaches from near 32N132W to 27N138W to 26N140w by early on Sunday, with southerly winds ahead of it on the diminishing trend. Northerly winds behind the front are expected to start of in the generally fresh range, but diminish quickly to the gentle category during Saturday as weak high pressure builds eastward in the wake of the front. A northwest swell behind the front will allow for 8 to 9 ft seas there through Sunday. With high pressure shifting eastward with the approach of this next cold front, the trades over the central and western portions of the area will weaken per latest model wind guidance indicating mostly gentle to moderate trades over those sections of the area. Seas within those areas will be in the 8-9 ft range due to combination of windwave northeast swell with a northwest swell through Saturday, then attributed to mainly a northwest swell component by Sunday. A mid/upper level trough is producing scattered showers and isolated thunderstorms over the far eastern portion of the area from 03N to 07N between 90W and 105W. This activity is expected to continue into early tonight. New similar activity may develop to its east tonight into Saturday. $$ Aguirre