000 AXPZ20 KNHC 142121 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2121 UTC Tue Jun 14 2016 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 2100 UTC. ...TROPICAL WAVES... A tropical wave is approaching the tropical northeast Pacific ocean, currently along the coast of Colombia to the north of 05N. Associated scattered moderate convection is to the north of 03N, west of the wave axis to 82W. A tropical wave is along 100w to the north of 10N, moving west around 10 knots. Associated scattered moderate convection is within 240 nautical miles to the northwest of a line from 15N93W to 07N100W. This tropical wave may merge with an area of low pressure located to the west of the tropical wave near 13N105W. ..INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 10N84W to low pressure near 13N105W to 10N114W. The intertropical convergence zone axis extends from 10N114W to 12N119W to 05N140W. Scattered moderate convection is from 03N to 10N between 87W and 92W, from 08N to 13N between 116W and 121W, and also from 04N to 08N between 124W and 136W. ...DISCUSSION... From 15N northward and from 120W eastward: A surface ridge extends from west of 120W to the southeast through 24N120W to 18N107W. Meanwhile 1011 mb low pressure is located near 13N105W and is moving to the west-northwest. Associated convection with the low includes scattered moderate within 150 nautical miles in the west quadrant. The ridge will gradually truncate and withdrawal from southeast to northwest as the low pressure area approaches. The low will reach to near 16N108W by Thursday afternoon, then will stall near 18N109W by Saturday afternoon where it will gradually dissipate through Sunday afternoon, with the ridging rebuilding thereafter. Mainly moderate winds will prevail through the next several days, except occasionally fresh offshore of the Baja California peninsula. Combined seas of 5 to 7 feet will build to 6 to 9 feet to the north of 28N and to the west of the Baja California peninsula tonight through the end of the week, due to the arrival of fresh northwest swell. In the Gulf of California, surface troughing lingers from northwest to southeast across the Gulf resulting in variable winds dependent on either side of the troughing. Wind speed magnitudes are light to moderate with seas generally 2 feet or less away from the entrance of the Gulf. Little change is forecast through the end of the week into the start of the upcoming weekend. Winds will then will veer to northerly Saturday night through Sunday across the northern Gulf as the troughing drifts slightly eastward, with magnitudes pulsing to moderate to fresh. These winds will build seas to 3 to 5 feet in the northern Gulf. In the Gulf of Tehuantepec, mainly light onshore flow is anticipated, shifting to offshore during the overnight hours with nocturnal drainage flow. Model guidance indicates offshore flow increasing to moderate to fresh by early Saturday morning, then increasing to fresh to strong by early Sunday morning which will build seas locally to 6 to 8 feet. From 15N southward and from 120W eastward: A tropical wave currently along the west coast of Colombia is moving into the area. Another tropical wave currently along 100W is forecast to merge with an 1011 mb area of low pressure currently near 13N105W. This low will gradually move to the west- northwest through the next several days. Otherwise, mainly gentle to moderate winds are expected on either side of the monsoon trough, with primarily a westward/onshore component, except during the overnight hours when nocturnal drainage flow will result in offshore winds. Cross-equatorial southwesterly swell will continue to propagate to the northeast with combined seas of 5 to 8 feet building to 6 to 9 feet tomorrow, gradually subsiding and decaying through the end of the week. Elsewhere to the west of 120W: A high pressure ridge remains over the northern waters. The difference in pressure between the ridging and lower pressure in the vicinity of the intertropical convergence zone axis will maintain moderate to fresh trade winds to the north of the axis. The ridge of high pressure will gradually weaken through the end of the week as a weak cold front or remnant trough drops into the far northern waters. That front/trough will stall out across the far northwest portion Friday, then will actually drift westward toward 140W at the start of the upcoming weekend, as high pressure ridging rebuilds from north of the area. $$ LEWITSKY