866 AXPZ20 KNHC 090325 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0325 UTC Sun Sep 9 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 W of the area in the Central Pacific basin near 21.8N 140.8W at 09/0300 UTC or 810 nm E of Hilo Hawaii moving W at 14 kt. Estimated minimum central pressure is 985 mb. Maximum sustained wind speed is 70 kt with gusts to 85 kt. Numerous moderate and scattered strong convection is within 120 nm of the center of Olivia, except within 90 nm in the NE quadrant. Additional scattered moderate convection is within 210 nm in the NE quadrant. Associated outer winds and seas will shift completely W of 140W between 24 and 36 hours. See latest CPHC forecast/advisory under AWIPS/WMO headers MIATCPCP5/WTPA35 PHFO for more details. Tropical Depression Eighteen-E centered near 16.1N 117.2W at 09/0300 UTC or 580 nm SW of the southern tip of Baja California moving W at 8 kt. Estimated minimum central pressure is 1006 mb. Maximum sustained wind speed is 30 kt with gusts to 40 kt. Numerous moderate and scattered strong convection is within 150 nm of the center of the depression, except 0 nm in the E quadrant. Additional scattered moderate convection is within 540 nm in the SW quadrant. The depression is forecast to strengthen to a tropical storm Sun morning with continued gradual strengthening through Tue night, with weakening thereafter and eventually becoming a post-tropical/remnant low by Fri night. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCPEP3/WTPZ33 KNHC for more details. ...TROPICAL WAVES... A tropical wave has an axis N of 06N along 82W with the northern portion extending across western Panama and through the western Caribbean Sea, moving westward at around 10 kt. Scattered moderate and isolated strong convection is within 300 nm W of the tropical wave axis. A tropical wave has an axis N of 05N along 100W with the northern portion extending across central Mexico, moving westward at 10 to 15 kt. Associated scattered moderate convection is from 06N to 09N between 98W and 101W. A tropical wave has an axis from 04N to 17N along 108W, moving westward at 5 to 10 kt. Associated scattered moderate and isolated strong convection is from 14N to 19N between 108W and 113W. This tropical 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 10N84W to 09N102W, then resumes from 16N133W to 13N140W. Scattered moderate and isolated strong convection is from 05N to 09N between 88W and 97W, and also from 09N to 12N between 101W and 106W. Similar convection is within 300 nm SE of axis W of 134W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features section for more details on Tropical Depression 18-E which is forecast to remain just W of the offshore waters. That being said, associated swells will spread northward into the waters SW of the southern Baja California peninsula including near the Revillagigedo Islands. In the Gulf of California, moderate southerly flow will increase to fresh in the northern Gulf tonight into early Sun while winds diminish over the southern portion. Winds will diminish across the Gulf through the remainder of the week. Seas will be 2 to 4 ft, except 4 to 6 ft in the northern Gulf as well as near the entrance of the Gulf during the stronger winds. Elsewhere, a weak pressure pattern will allow for mainly gentle onshore winds through Mon night. The pressure gradient will tighten Tue through Thu night allowing for winds to increase to moderate W of 110W. Long period southerly swell is forecast to propagate into the offshore waters by the middle of the week. 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 the remainder of the week. REMAINDER OF THE AREA... Please see the Special Features section for details on Hurricane Olivia which has now shifted just W of 140W, and on Tropical Depression Eighteen-E. Otherwise, a ridge drops S into the area between Olivia and the Tropical Depression with mainly moderate winds, except northerly winds have increased to fresh in the N central waters where fresh northerly swell has arrived with seas of 8 to 9 ft. This swell and winds will linger through the early part of the week, gradually diminishing and subsiding through the remainder of the week. $$ Lewitsky