986 AXPZ20 KNHC 081614 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Sat Sep 8 2018 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 1200 UTC surface analysis and satellite imagery through 1500 UTC. ...SPECIAL FEATURES... Hurricane Olivia centered near 21.4N 138.0W at 1500 UTC or 965 nm E of Hilo Hawaii moving WNW at 13 kt. Estimated minimum central pressure is 983 mb. Maximum sustained wind speed is 75 kt with gusts to 90 kt. The large eye of Olivia has become somewhat ragged early this morning, while scattered to numerous moderate to strong convection is occurring in the eyewall within 60 nm in the E semicircle and 45 nm in the W semicircle. Olivia is forecast to continue moving westward and gradually weaken, and will pass across 140W and into the Central Pacific basin tonight while maintaining minimal hurricane strength. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCPEP2/WTPZ32 KNHC for more details. Elongated low pressure near 116W has become sufficiently organized early this morning to become Tropical Depression Eighteen-E, located near 16.1N 115.9W at 1500 UTC, moving WNW at 10 kt. Minimum central pressure is estimated at 1006 mb. Associated scattered moderate to strong convection has become clustered within 240 nm across the SW semicircle. The depression is expected to bring increasing winds and seas over a portion of the Pacific waters roughly from 08N to 20N between 108W and 126W through at least Mon, as it gradually intensifies and moves WNW to NW, remaining to the W of the offshore waters. ...TROPICAL WAVES... A tropical wave has an axis N of 04N along 96W with the northern portion extending across eastern Mexico, moving westward at 10 to 15 kt. Associated scattered moderate to strong convection is occurring within 150 nm of the coastline between 90W and 99W, and within 210 nm s of the monsoon trough. A tropical wave has an axis N of 05N along 103W to the southern coast of Mexico, moving westward at 5- 0 kt. Associated convection has diminished with widely scattered showers and thunderstorms east of the wave axis near the monsoon trough. This wave continues to weaken and is expected to merge with the wave to the east during the next 48 hours. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from near 11N85W to 08N97W to 14N106W to low pres near 15N115.5W to 11N122W. Scattered moderate to strong convection is within 210 nm of the trough. Scattered moderate and isolated strong convection is located in the W central waters where the monsoon trough has become diffuse. This convection is from 10N to 14N between 135W and 139W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A surface trough will meander between the the Gulf of California and the Baja California Peninsula the next few days. A ridge building modestly between Baja California and departing Hurricane Olivia will produce moderate to fresh NW winds W of the Baja peninsula through early today, eventually diminishing to gentle by Sun. SW swell from the new Tropical Depression Eighteen-E, located SW of the offshore waters of southern Mexico, will spread N and NE to build seas across the offshore waters to 7 to 8 ft throughout the day. Gentle to moderate winds are expected elsewhere over the Mexico offshore waters through the weekend, with seas of 5 to 7 ft over the Pacific waters. In the Gulf of California, moderate winds varying in direction on either side of the trough will increase to moderate to fresh in the northern Gulf late tonight even briefly reaching strong early Sun. Seas will start out in the 1 to 3 ft range across the Gulf, except 3 to 5 ft near the entrance, and will build to 2 to 4 ft elsewhere by late tonight into Sun as the winds increase. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... The monsoon trough will meander between 08N and 10N during the next few days. Winds on both sides of the trough axis will be gentle to moderate. Long period cross equatorial SW swell propagating into the area has resulted in seas building to 6 to 9 ft between Colombia and the Galapagos Islands. This swell will persist through the weekend, then begin to subside early Mon, before another pulse arrives late Mon through Wed night. REMAINDER OF THE AREA... Please see the Special Features section for details on Hurricane Olivia, and on newly named Tropical Depression Eighteen-E. Otherwise, a ridge drapes across Olivia and dominates the forecast waters N of 20N W of 120W, producing gentle to moderate easterly winds south of 30N and west of 122W. Seas generated by Olivia will continue to spread across the waters north of 12N and west of 120W over the weekend. $$ Stripling