000 AXPZ20 KNHC 032218 CCA TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2218 UTC Tue Apr 3 2018 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 2130 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough reaches from 08N84W to 03N100W. The intertropical convergence zone reaches from 03N100W to beyond 06.5N140W. Scattered moderate convection is noted within 90 nm either side of the ITCZ between 117W and 128W, and within 120 nm north of the ITCZ west of 138W. Farther south, a second intertropical convergence zone extends from 03.4S94W to 02S100W to 03.4S110W. No significant convection is noted. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A ridge extends SE across the offshore forecast waters through the Revillagigedo Islands maintaining mainly gentle to moderate NW-N winds, and seas of 4 to 6 ft in open waters. Little change in these marine conditions is expected into Thu. An upper disturbance will shift eastward across the region late Thu, allowing moderate to locally fresh NW-N winds and seas in the 5-8 ft range mainly in the waters N of Cabo San Lazaro as ridging builds in the wake of the disturbance. Farther south in the Gulf of Tehuantepec, a weak pressure pattern supporting generally light winds will transition through mid week as high pressure builds north of the region. This will support fresh to strong gap winds through the Gulf of Tehuantepec late Wed night into Thu. Currently, marine guidance suggests northerly winds of 20-30 kt and seas in the 6-9 ft range with this event. Climatologically speaking, the final gale force gap wind event occurs in the Gulf of Tehuantepec in late March or early April. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Mmoderate NE to E gap winds and 3 to 5 ft seas will increase to fresh gap winds and 4 to 7 ft seas Thu as high pressure builds north of the region. Gentle to moderate winds will prevail the remainder of the forecast period. Gulf of Panama: gentle to moderate N-NE winds will prevail through Wed, with seas of 3 to 5 ft in long period SW swell. Light and variable winds are expected thereafter. Elsewhere, light and gentle winds are generally expected, with a better defined southerly wind flow S of 07N/08N by Thu. Seas of 5-7 ft in long period SW swell will subside to 3-5 ft Wed through Fri. REMAINDER OF THE AREA... A broad ridge dominates the forecast region north of 15N and W of 110W related to 1021 mb high pressure located well N of the area near 36N129W. A new high pressure center is forecast to develop along the ridge axis over the northern forecast waters near 26N125W, and it will remain nearly stationary over the next 48 to 72 hours. The pressure gradient between the ridge and lower pressures in the vicinity of the ITCZ will result in moderate to locally fresh trade winds and seas to near 8 ft, particularly across the waters from 08N to 15N W of 125W through late in week. A new cold front approaching from the west will bring an increase in winds and seas across the far NW waters by Wed. Expect fresh to strong southerly winds and seas of 8-9 ft ahead of the front and NW of a line from 30N136W to 27N140W by late Wed. Winds will increase again across the NW corner of the forecast region Thu night into Fri in association with a strong low pressure system crossing N of the area. $$ Christensen