000 AXPZ20 KNHC 150945 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 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 0600 UTC surface analysis and satellite imagery through 0830 UTC. ...TROPICAL WAVES... A tropical wave is along 81W/82W from 15N southward, moving westward about 15 knots. The wave extends from the southwestern Caribbean Sea, across Panama, into the eastern Pacific Ocean. Convective precipitation: Widely scattered moderate to isolated strong is from 02N to 05N between 75W and 82W. ..INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough is along 09N/10N between 85W and 95W. The monsoon trough also extends from a 1010 mb low pressure center that is near 13N106W, to 10N110W and 10N119W. The ITCZ starts near 10N119W, and it continues to 11N124W, 06N134W, and beyond 05N140W. Convective precipitation: scattered to numerous strong within 150 nm to the north of the ITCZ between 122W and 126W. Scattered moderate to isolated strong is elsewhere within 180 nm to the north of the monsoon trough/ITCZ. Scattered strong from 08N TO 12N between 96W and 102W. Scattered moderate to isolated strong is within 180 nm to the south of the monsoon trough between 90W and 95W. Isolated moderate to locally strong within 390 nm to the south of the monsoon trough from 101W eastward, and within 150 nm to the north of the monsoon trough between 95W and 97W. Scattered moderate to isolated strong from 14N northward between 99W and 103W. A surface trough extends from the 1010 mb low pressure center that is near 13N106W to 19N109W. ...DISCUSSION... From 15N northward and from 120W eastward: A surface ridge extends from the waters that are outside this area, into the western half of the area. The ridge is along 20N109w, 23N117W, 26N126W, beyond 32N140W. A 1010 mb low pressure center is near 13N106W. The low center is nearly stationary with a northward drift. Convective precipitation: scattered moderate to isolated strong within 180 nm of the low center in the northwestern quadrant. The surface ridge will truncate gradually, and withdraw from southeast to northwest as the low pressure area approaches. The low center will be near 15N107W by early Thursday morning, near 17N109W by early Friday morning, near 19N110W by early Saturday morning, and it is forecast to be dissipating near 19N111W early on Sunday morning. The surface ridge will re-develop again after the low pressure center dissipates. 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 8 to 9 feet to the north of 24N and to the west of the Baja California peninsula tonight through the end of the week, due to the arrival of fresh northwest swell. The Gulf of California: a surface trough will linger from northwest to southeast across the Gulf resulting in variable winds dependent on either side of the trough. The wind speeds will be 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. The wind speeds will veer to northerly Saturday night through Sunday across the northern Gulf as the trough drifts slightly eastward, with magnitudes pulsing to moderate to fresh. These winds will build seas to 3 to 5 feet in the northern Gulf. 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 Sunday morning, becoming moderate on Monday morning. The sea heights will start at 6 feet this morning, reach 7 feet by Thursday morning, and then stay in the range from 5 feet to 6 feet for the next 3 days to 4 days. From 15N southward and from 120W eastward: A 1010 mb low pressure center is near 13N106W, nearly stationary. The low center will be near15N107W by early Thursday morning, near 17N109W by early Friday morning, near 19N110W by early Saturday morning, and it is forecast to be dissipating near 19N111W early on Sunday morning. Expect mainly gentle to moderate winds 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 feet to 8 feet, building to 6 feet to 9 feet tomorrow, gradually subsiding and decaying through the end of the week. Elsewhere to the west of 120W: A surface ridge remains in the northern waters. The difference in pressure between the ridge and the lower pressure in the vicinity of the intertropical convergence zone will maintain moderate to fresh trade winds to the north of the ITCZ. The surface ridge will weaken gradually 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 part of the area on Friday, and then it will drift westward toward 140W at the start of the upcoming weekend, as a ridge builds from north of the area again. $$ mt