000 AXPZ20 KNHC 181001 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 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 0600 UTC surface analysis and satellite imagery through 0945 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from northern Colombia to 09N90W to to 10N108W and to 08N115W, where latest scatterometer data indicates that it transitions to the ITCZ to 07N140W to 08N131W and to beyond 07N140W. Scattered moderate to isolated strong convection is within 120 nm south of trough between 78W- 80W and between 97W-99W, and within 60 nm south of trough between 99W-102W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... High pressure centered well NW of the area is dominating waters offshore Baja California. The associated gradient is allowing for mainly fresh northwest winds to exist over these waters, with seas in the range of 6-9 ft due to a long-period south to southwest swell. Winds will further 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. The 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 south of the Gulf of Tehuantepec region. Gulf of California: Gentle to moderate winds with seas of 3 to 4 feet are expected through the rest of the week, with the exception of the northern part of the Gulf, where fresh southeast winds 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 to 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 today, before diminishing to mainly gentle speeds again through late in the week. 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 northern waters. 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 111W, 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. $$ Aguirre