000 AXPZ20 KNHC 051605 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Wed Apr 5 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. ...SPECIAL FEATURE... GULF OF TEHUANTEPEC GALE WARNING: A cold front will quickly move across the Gulf of Mexico today. High pressure building in behind the front will help usher in the next Gulf of Tehuantepec gale force gap wind event. Winds will strengthen this evening and rapidly increase to gale force by early Thursday morning. The northerly winds will continue to strengthen Thursday. Winds will increase to 40 kt by Thursday evening, with seas forecast to build to a max of 15 ft just downstream of the Gulf of Tehuantepec. Winds may briefly diminish to just below gale force briefly late Fri morning, but will once again increase to minimal gale force on Fri evening. Winds will diminish to below gale force Saturday, and continue to diminish to 20 kt or less by Sunday morning. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A trough extends from 07N77W to 04N85W to 04N94W. The ITCZ axis extends from 04N94W to 03N109W to 04N123W where it briefly ends. It resumes at 06N125W to 06N140W. Scattered moderate isolated strong convection is noted within 60 nm of the trough between 91W-94W. No significant convection is associated with the ITCZ. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See special features above for more on the upcoming Gulf of Tehuantepec gale force gap wind event. High pressure centered west of the area extends a ridge eastward to near the Revillagigedo Islands. Outside of the Gulf of Tehuantepec region, gentle to moderate northwest to north flow will prevail across the offshore waters. Winds will strengthen over the offshore waters off the west coast of Baja California Norte on Sunday as the pressure gradient tightens between the ridge and troughing along Baja California. Gulf of California: Gentle to moderate northwest winds will prevail through Thursday before weakening slightly on Friday. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: High pressure building north of the area will help increase nocturnal pulsing of winds over the Gulf of Papagayo starting late tonight. Gulf of Panama: Moderate to fresh nocturnal flow is expected during the overnight hours through the remainder of this week. Elsewhere, light to gentle winds, and combined seas of 3 to 5 ft, will prevail. REMAINDER OF THE AREA... The pressure gradient between high pressure over the northern waters and lower pressure in the vicinity of the ITCZ is supporting gentle to moderate trades over the tradewind belt. Seas associated to the latest northwesterly swell train have been subsiding, with seas 8 ft or greater only a covering small area from 04N to 14N between 108W and 123W. Seas will subside below 8 ft over this area tonight, however seas to 8 ft are expected south of 01S between 104W and 112W early Thursday, and south of 02S between 108W and 118W by early on Friday. A surface trough is analyzed from 04N124W to 09N122W moving westward about 15 kt. Latest satellite imagery shows scattered moderate/isolated strong convection in clusters from 03N to 08N between 119W-124W. The trough will reach near 129W/130W Thursday and to near 138W/139W by Friday. A fresh set of northwesterly swell has reached the far northwest corner of the area in advance of a cold front that has crossed into the far northwest corner of the area. The swell is confined to the northwest of a line from 32N136W to 29N140W. Seas produced by this swell are peaking to 10 ft. The front will dissipate by early Thursday. Models depict that another cold front will be just the northwest of the area by Thursday evening. Yet another set of northwesterly swell will propagate into much of the northern waters by then, with seas peaking up to 11 ft to the north of a line from 32N127W to 25N134W to 25N140W. The front is forecast to reach a position from near 32N136W to 28N140W by early on Friday, with strong northwest winds behind it along with seas of 10-13 ft in northwesterly swell. Seas of 8-12 ft are forecast elsewhere northwest and north of a line from 32N118W to 27N130W to 26N135W to 25N140W at that time. $$ Aguirre