593 AXPZ20 KNHC 080300 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0300 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 0000 UTC surface analysis and satellite imagery through 0230 UTC. ...SPECIAL FEATURES... Hurricane Olivia centered near 20.9N 135.2W at 08/0300 UTC or 1120 nm E of Hilo Hawaii moving WNW at 13 kt. Estimated minimum central pressure is 975 mb. Maximum sustained wind speed is 85 kt with gusts to 105 kt. Numerous moderate to strong convection is occurring within 90 nm in the SE semicircle of Olivia, and within 75 nm in the NW semicircle. Olivia is forecast to continue moving WNW and gradually weaken, and will pass across 140W and into the Central Pacific basin Sat night while maintaining minimal 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 15N113.5W is moving westward around 5 to 10 kt. Associated scattered moderate to strong convection is within 420 nm in the SW quadrant of the low and within 210 nm in the NW quadrant of the low with minimal convection on the eastern half of the system. 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 125W Fri through at least Mon, as it gradually becomes better organized. This low has a high chance of tropical cyclone formation during the next 48 hours. ...TROPICAL WAVES... A tropical wave has an axis along about 92W N of 03N across western Guatemala and entering eastern Mexico, moving westward at 10 to 15 kt. Associated scattered moderate and isolated strong convection is from 04N to 08N between 89W and 92W. A tropical wave has an axis along about 100W to the N of 06N, moving westward at around 10 kt. Associated scattered moderate convection is from 11N to 13N between 100W and 102W. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from northern Colombia near 10N75W to 10N89W to 09N95W to 13N106W to low pressure near 15N113.5W to 14N121W. No significant convection outside of the convection mentioned with the tropical waves above is present. Scattered moderate convection is located in the W central waters where the monsoon trough has become diffuse. This convection is within 180 nm SE of a line from 14N131W to 11N140W. Also, scattered moderate to strong convection is moving offshore of Mexico near Cabo Corrientes from 19N to 21N within 45 nm of shore. ...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, diminishing to gentle by Sun. SW swell from a developing tropical low 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 by Sat. 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 Sat night 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 Sat night 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 7 to 9 ft between Ecuador and the Galapagos Islands. This swell will spread into the waters of Colombia 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 Wed night. REMAINDER OF THE AREA... Please see the Special Features section for details on Hurricane Olivia, and on developing low pressure near 15N113.5W. 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. $$ Lewitsky