000 AXPZ20 KNHC 150222 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0222 UTC Wed Jun 15 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 0000 UTC surface analysis and satellite imagery through 0200 UTC. ...TROPICAL WAVES... A tropical wave is along 80W to the north of 05N extending through central Panama and into the southwest Caribbean Sea. The tropical wave is moving west around 15 kt. Associated scattered moderate convection is to the north of 05N and east of 86W. A tropical wave that was previous analyzed along 100W has become diffuse as it interacts with low pressure near 13.5N103.5W. ..INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 10N84W to low pressure near 13.5N103.5W to 09N110W to 11N116W. The intertropical convergence zone axis extends from 11N116W to 08N130W to 05N140W. Scattered moderate and isolated strong convection is from 09N to 15N between 95W and 103W, within 180 nm to the north of the axis between 106W and 126W, and also within 150 nm either side of the axis between 126W and 137W. ...DISCUSSION... From 15N northward and from 120W eastward: A surface ridge extends from west of 120W to the southeast through 25N120W to 18N108W. Meanwhile 1011 mb low pressure is embedded in the monsoon trough near 13.5N103.5W. This low is nearly stationary with a northward drift. Associated convection includes scattered moderate within 240 nm in the northwest 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 evening, then will stall near 18N109W by Saturday morning 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: Outside of the tropical wave mentioned above along 80W to the north of 05N, the only other significant surface feature analyzed is the 1011 mb low pressure center near 13.5N103.5W. This low is currently nearly stationary but will gradually move to the west- northwest through the next few days before dissipating. 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