540 AXPZ20 KNHC 082214 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 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 1800 UTC surface analysis and satellite imagery through 2100 UTC. ...SPECIAL FEATURES... Hurricane Olivia centered near 21.7N 139.4W at 2100 UTC or about 890 nm E of Hilo Hawaii moving W at 13 kt. Estimated minimum central pressure is 983 mb. Maximum sustained wind speed remains 75 kt with gusts to 90 kt. The ragged eye of Olivia has remained evident in infrared satellite imagery today. Presently scattered moderate to strong convection is occurring in the eyewall within 75 nm of the center except 60 nm across the NE quadrant. 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. Tropical Depression Eighteen-E is located near 15.8N 116.8W at 2100 UTC, moving WNW at 10 kt. Minimum central pressure is estimated at 1006 mb. Maximum sustained winds remain 30 kt gusting to 40 kt. The low level circulation of this system remains somewhat elongated NE to SW, however afternoon satellite imagery suggests slow and gradual improvement in the overall organization. Associated scattered moderate to strong convection is occurring within 30 nm NE...90 nm SE...210 nm SW...AND 120 nm NW quadrants. As the depression moves WNW to NW over the next few days, it is expected to gradually intensify to a tropical storm and bring increasing winds and seas over a portion of the Pacific waters roughly from 08N to 20N between 108W and 126W through Mon, while remaining to the W of the offshore waters. ...TROPICAL WAVES... A tropical wave has an axis N of 04N along 96W-97W with the northern portion extending across SE Mexico, moving westward at 10 to 15 kt. Associated scattered moderate to strong convection is occurring within 270 nm of the coastline between 91W and 100W, and within 150 nm S of the monsoon trough. A tropical wave has an axis N of 05N along 104W to the southern coast of Mexico, moving westward at 5-10 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 10.5N74W TO 10N92W TO 08.5N98W TO 17N112W. The ITCZ extends from 16N131W TO 13N140W. Scattered moderate to strong convection is from 06N to 13N between 82W and 97W, within 150 nm S of the trough between 97W and 105W, and within 120 nm S of the ITCZ. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A surface trough will meander between the far northern Gulf of California and the Baja California Peninsula the next few days. A ridge building modestly between Baja California and departing Hurricane Olivia is aiding in producing moderate to fresh NW winds W of the Baja peninsula today, but will eventually diminish 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 and into Sunday. 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 tonight and briefly become strong early Sun. Seas will start out in the 1 to 3 ft range across the Gulf, and will build to 2 to 4 ft elsewhere by late tonight into Sun as the winds increase. Expect seas 3 to 5 ft to prevail near the entrance to the Gulf. 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 18N W of 120W, producing gentle to moderate easterly winds south of 30N and west of 118W. Seas generated by Olivia will continue to spread across the waters north of 12N and west of 126W over the weekend. $$ Stripling