000 AXPZ20 KNHC 181549 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Tue May 18 2021 Tropical Weather Discussion for the eastern Pacific Ocean from 03.4S to 30N, east of 120W including the Gulf of California, and from the Equator to 30N, between 120W and 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 1500 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 08N78W to 10N90W to 10N115W. The ITCZ extends from 10N115W to 06N125W to 09N140W. Scattered moderate convection is noted from 03N to 07N east of 84W. Scattered moderate to isolated strong from 06N to 10N between 92W and 104W. Scattered moderate convection is noted from 04N to 07N between 118W and 122W, from 09N to 12N between 122W and 129W, and from 10N to 13N between 132W and 135W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A few ship observations confirm generally moderate to fresh NW winds persist off Baja California this morning. A concurrent altimeter satellite pass indicated seas mostly 5 to 6 ft, but reaching near 7 ft in some areas. These winds and seas are on the western edge of a broad subtropical ridge extending to the south of Los Cabos and through Socorro Island. Light to gentle breezes and slight seas are noted in the Gulf of California. Farther south, gentle W to NW breezes persist over Mexican offshore waters south of Cabo Corrientes. Seas are 5 to 7 ft however, mainly in longer period SW swell. For the forecast, the high pressure centered west of Baja California will continue to support mainly moderate to locally fresh northwest to north winds through mid week. Winds will increase to fresh to strong speeds mainly west of central and northern Baja California beginning late Thu as stronger high pressure builds southeastward across the waters west of Baja California. South to southwest swell will build seas as it propagates across the waters north of Punta Eugenia beginning today. Looking ahead for later in the week, a trough or low may form well south of the Gulf of Tehuantepec region. For the Gulf of California, expect fresh southeast winds to develop Wed in advance of a cold front that moves over far southern California and the far northern part of Baja California. These winds become briefly become fresh or even strong southwest to west winds late Thu night as the tail-end of the front moves across far northern Baja California and the northern Gulf of California. Seas will build to around 6 ft with these winds. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, and WITHIN 750 NM OF ECUADOR... Gentle east winds in the Papagayo region will pulse to moderate speeds this afternoon, before diminishing to mainly gentle speeds again through Fri. Fresh gap winds may return to the Gulf of Papagayo by Sat. Seas of 5-7 ft will change little into late in the week. Long period cross- equatorial southerly swell will continue to impact the offshore forecast waters through Fri night, then begin to subside on Sat. Seas of 6-8 ft between Ecuador and the Galapagos Islands will begin to build to 8 ft or higher on Wed as additional pulses of long- period southwest swell begin to propagate through those waters. REMAINDER OF THE AREA... High pressure ridging continues to dominate the waters north of 15N. The pressure gradient between it and comparatively lower pressures in the tropical zone area is leading to a large area of moderate to fresh trade winds north of the ITCZ, with seas up to 8 ft. Gentle to moderate trade winds are noted elsewhere, with seas in the range of 6-7 ft mainly due to a southerly swell component. By late Fri, the area of moderate to fresh trade winds will have expanded to encompass the waters west of a line from 21N116W to 08N129W as the high pressure over the region strengthens. Long period cross-equatorial southerly swell over the waters south of about 11N and east of about 110W, except in the lee of the Galapagos Islands will be replaced by a new set of long- period southerly swell beginning today. This new set of southerly swell will propagate through these same waters through late Wed night, then begin to decay through Fri night. Before doing so, it is expected to raise seas to a peak of 10 or 11 ft over the far south-central waters west of the Galapagos Islands. $$ Christensen/Aguirre