106 AXPZ20 KNHC 071617 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Fri Sep 7 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 is centered near 20.1N 132.5W at 1500 UTC or about 1273 nm E of Hilo Hawaii, moving WNW at 14 kt. Estimated minimum central pressure is 964 mb. Maximum sustained wind speed is 100 kt with gusts to 120 kt. Satellite imagery this morning shows Olivia with a large 30 nm wide eye, with numerous moderate to strong convection occurring from 15 to 90 nm of the center. Olivia is forecast to continue moving WNW and pass across 140W and into the Central Pacific basin Sat night while maintaining hurricane strength. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCPEP2/WTPZ32 KNHC for more details. Elongated low pressure of 1008 mb is analyzed near 14.5N113W moving westward around 10 kt. This main surface low is along the northern end of an elongated cyclonic circulation associated with a tropical wave which along about 112W-113W. Scattered moderate to strong convection is within 180 nm either side of a line from 20N108W TO 10N118W. This system is expected to bring increasing winds and seas over a portion of the Pacific waters roughly from 08N to 20N between 108W and 120W Fri through at least Mon. This low has a medium chance of tropical cyclone formation during the next 48 hours. ...TROPICAL WAVES... A tropical wave has an axis along about 85W-86W north of 04N across Central America to the NW Caribbean Sea, moving westward at 10 to 15 kt. Only isolated showers and thunderstorms are currently accompanying this tropical wave. A tropical wave has an axis along about 98W-99W to the north of 07N, moving westward at 10-15 kt. Moderate to strong convection is scattered about the area from 07N to 15.5N between 94W and 103.5W. Please see the Special Features section for information on the area of low pressure along a tropical wave at 112W-113W. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from low pressure over northern Colombia near 10N74W to 08N82W to 10N97W to low pressure near 14.5N113 TO 11N118W, then resumes from 15N130W to 13N137W. Scattered moderate to strong convection is noted within 180 nm s of the trough between 132W and 137W. Scattered moderate to strong convection that developed inland overnight across western Mexico continues to propagate NW and is offshore from 22N to 25.5N from 109W to the coast of Mexico, which coverts the entrance to the Gulf of California. ...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 between Baja California and departing Hurricane Olivia will produce moderate to fresh NW winds W of the Baja peninsula through early Sat. SW swell from a developing tropical low SW of the offshore waters of southern Mexico will spread north and northeastward to build seas across the offshore waters to 7 to 8 ft by Sat. Northerly winds across the offshore waters of the Gulf of Tehuantepec has increased to 15-20 kt this morning. 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, and 1 to 3 ft over the Gulf of California. 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 region this morning will build seas to near 8 ft and greater, at first between Ecuador and the Galapagos Islands through this morning, then into the waters of Colombia by late tonight, persisting through much of the weekend. The swell will begin to subside by the end of the weekend into early next week, with another pulse arriving by late Mon through Tue night. REMAINDER OF THE AREA... Please see the Special Features section for details on Hurricane Olivia, and on developing low pressure near 15N111W. 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 upcoming weekend. $$ Stripling