000 AXPZ20 KNHC 052201 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Wed Apr 05 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 1800 UTC surface analysis and satellite imagery through 2145 UTC. ...SPECIAL FEATURE... GULF OF TEHUANTEPEC GALE WARNING... A cold front will sweep se across the Bay of Campeche this evening resulting in strong n winds to surge into the Gulf of Tehuantpec this evening. These n winds will then increase to minimal gale force at sunrise on Thu. The northerly winds will continue to strengthen throughout Thu with 30 to 40 kt winds, and seas to 15 ft, expected just downstream of the Gulf of Tehuantpec on Thu evening. These winds will diminish to just below gale force briefly late Fri morning, but increase again to minimal gale force on Fri evening, and then continue through late Fri night. Expect only fresh n winds just before sunrise on Sun. The resultant ne swell, in the form of 8 ft seas or greater, will propagate sw mixing with long period cross- equatorial sw swell, to along 08N between 97W and 105W on Fri night before beginning to subside. Expect seas to subside to less than 8 ft late Sat night. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A 1009 mb surface low is over nw Colombia at 08N74W with a surface trough extending sw along 07N78W to 04N83W to 04N96W where scatterometer winds indicate that the ITCZ forms and continues w to 03N114W, then turns nw through another surface trough at 07N125W, then turns wsw to beyond 06N140W. Scattered moderate isolated strong convection is observed over and to the n of the eastern trough within 60 nm either side of a line from 07N78W to 04N97W. Similar convection is noted over and the n of the the ITCZ within 180 nm either side of a line from 03N120W to 10N124W, and is associated with an embedded surface trough analyzed from 03N126W to 11N124W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See special features above for the Gulf of Tehuantepec area. A surface ridge extends se along 22N116W to 13N96W. Gentle to moderate n flow is expected through Fri night across the offshore waters w of 105W. The pressure gradient will then tighten with fresh nw winds w of the Baja Peninsula on sat afternoon, expect for a narrow band of strong nw winds along the Baja California Norte as seas build 7 to 11 ft. Gulf of California: Gentle to moderate nw winds expected through Thu morning, then light winds on Fri. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Fresh to locally strong drainage winds expected tonight. A more significant event os forecast on Thu, Fri and Sat nights. The resultant ne swell will propagate wsw to near 08N92W on Sat. Strong ne pulses expected on Sun and Mon nights. Gulf of Panama: Moderate to fresh nocturnal flow expected during the overnight hours through Mon night. Light to gentle winds, and combined seas of 3 to 5 ft, are occurring elsewhere outside of the swells originating near the gap events. REMAINDER OF THE AREA... Moderate to locally fresh ne trades expected across the tropics from 05N to 15N w of 110W this week. A batch of northerly swell is subsiding, and expect seas of 5 to 7 ft across the tropical waters through early Fri. The first of three cold fronts has moved into the far nw waters and is accompanied by a fresh sw-w-nw wind shift. Large nw swell in the form of combined seas of 8 to 11 ft are noted about 180 nm e of the front. This initial front will begin to weaken along a position from 32N133W to 27N140W on Thu. By then a stronger cold front will reach near 32N140W preceded by a strong sw-w-nw wind shift, and maximum seas of 15 ft reaching as far s as 32N behind the front. This second front will begin to weaken on Thu night as a third cold front enters the nw waters accompanied by a strong to near gale force wind shift, with maximum seas of 17 ft w of the along 32N. $$ Nelson