475 AXPZ20 KNHC 161003 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Sun May 16 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 northwestern Colombia to 08N78W to 07N90W to 09N105W to 10N115W and to low pressure near 10N127W 1011 mb. ITCZ extend from the low pressure to 07N130W and to beyond the area at 06N140W. Scattered moderate to isolated strong convection is within 180 nm south of the trough between 78W-81W, and within 180 nm north of the trough between 109W-111W. Scattered moderate convection is within 180 NM south of the trough between 89W-92W and within 60 nm north of the ITCZ between 130W-133W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A somewhat tight gradient between the western periphery of Atlantic high pressure that extends to the western Gulf and relatively lower pressure across southeastern Mexico and near the Gulf of Tehuantepec region is presently inducing moderate to fresh northwest to north winds over the Gulf of Tehuantepec. These winds will become light and variable during today as the gradient weakens. Moderate to fresh northwest winds are west of Baja California along with seas of 5-6 ft. Seas are 3-4 ft in the Gulf of California, except for higher seas of 4-6 ft in the northern part of the Gulf, where fresh to locally strong southwest winds are occurring. As for the forecast, the winds west of Baja California will change little through Wed, then 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 fresh to locally strong southwest winds over the northern Gulf of California will continue through late Sun night. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, and WITHIN 750 NM OF ECUADOR... Fresh to strong northeast to east winds are over the Gulf and Papagayo and vicinity waters. Seas in that area are peaking to 9 ft. These winds will diminish to fresh speeds this afternoon, with seas subsiding to just below 8 ft. Gentle to moderate winds are noted elsewhere, with seas of 5-7 ft due to a long-period south to southwest swell. These winds are will forecast to change little through Wed. The south to southwest swell will continue through Thu night as extensive pulses of southern hemispheric swell energy cross the Equator. REMAINDER OF THE AREA... A rather broad surface ridge is the main feature over this part of the area controlling the prevailing wind regime. It is anchored by a strong 1033 mb high center that is well northwest of the area near 38N146W. A 1011 mb low is along the monsoon trough near 10N127W. The pressure gradient between the low and the high pressure is presently allowing for mainly fresh northeast to east winds over the waters from 11N to 13N between 125W-130W, with peak seas of 8 ft due a combination of generated wind waves combining with a northeast to east swell component present there. Gentle to moderate trade winds noted elsewhere over these waters, with seas in the range of 6-7 ft mainly due to s southerly swell component. As for the forecast, the aforementioned low will track to near 10N129W this afternoon. A slight tightening of the gradient between it and the high pressure to the north will allow for winds north of the low to increase to fresh to strong speeds from 11N to 14N between 127W-130W. By late tonight, the low is forecast to reach near 10N132W with pressure of 1011 mb. The fresh to strong winds will continue to its N, with seas in the range of 8-10 ft. By early Mon afternoon, the low is forecast to weaken to a trough from near 12N133W to 09N134W, with winds diminishing to fresh speeds from 11N to 14N between 127W-135W and resulted seas of 8-9 ft primarily due to a long-period south swell. The trough is forecast to reach from near 12N135W to 09N136W by Mon night. The swell near it will be mixed resulting in 8 ft seas from 12N to 15N between 133W-136W. The gentle to moderate trade winds elsewhere are expected to continue through late Sun night, then increase slightly in speeds to within 300 nm north of the ITCZ through Tue. Model guidance indicates that these winds then increase over most of the area through late in the week as stronger high pressure builds over the area. Southerly swell crossing the equator will maintain seas of 8-10 ft across the southern waters south of about 09N and east of 120W through tonight. These seas will gradually subside through late Mon as the swell decays. The guidance shows another set of long-period southerly swell moving through the far southern waters east of 125W by mid-week. $$ Aguirre