000 AXPZ20 KNHC 181559 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Mon Sep 18 2017 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 1545 UTC. ...SPECIAL FEATURES... Recently downgraded Tropical Storm Otis is centered near 19.0N 127.4W at 18/1500 UTC or about 1000 nm WSW of the southern tip of the Baja California peninsula moving N at 2 kt. Estimated minimum central pressure is 993 mb. The maximum sustained wind speed has diminished to 60 kt with gusts to 75 kt. Otis is forecast to slow down some while moving northward today, then to the NW tonight as it continues to weaken and weaken further to depression by early on Tuesday near 19.3N 128.1W, with maximum sustained winds 30 kt gusts to 40 kt. Otis is forecast to sharply turn to SW tonight, and continue on that motion through on Wednesday. The latest NHC advisory has Otis weakening to a post- tropical remnant low near 18.7N 128.9W by Tuesday evening, reaching near 17.8N 130.0W early on Wednesday, and to near 16.0N 132.5W early on Thursday with maximum sustained winds 20 kt gusts to 30 kt. Latest satellite imagery animation over the past 12 hrs shows convection on a rapid diminishing trend, with the only remaining convection characterized as the scattered moderate type intensity within 30 nm of the center, and also within 30 nm of 20N127W. Elsewhere, the cyclone is presently depicted as a swirl, about 120 nm in diameter, consisting of low and mid- level clouds with isolated showers and thunderstorms that surrounds the cyclone. Please read the latest NHC Forecast/Advisory under AWIPS/WMO headers MIATCMEP5/WTPZ25 KNHC for additional details. Tropical Storm Norma is centered near 21.4N 112.3W at 18/1500 UTC or roughly about 150 nm SW of Cabo San Lucas, Mexico moving W at 4 kt. Estimated minimum central pressure is 1000 mb. The maximum sustained wind speed is 45 kt with gusts to 55 kt. Norma is forecast to gradually weaken through tonight as it moves WNW to the W of the Baja California peninsula through the next couple of days. Latest NHC advisory has it becoming a tropical depression near 22.1N 115.0W by early Tuesday evening with maximum sustained winds 30 kt gusts to 40 kt. Latest satellite imagery shows deep convection increasing during the morning, with convection of the scattered moderate to strong type intensity within 60 nm of the center in the NW quadrant, and within 45 nm of the center in the NE quadrant. Scattered moderate isolated strong convection marks an outer rain band within a 30 nm of a line from 19N111W to 20N109W. Scattered moderate convection is within 60 nm of 21N111W. Please read the latest NHC Forecast/Advisory under AWIPS/WMO headers MIATCMEP2/WTPZ22 KNHC for additional details. ...TROPICAL WAVES... A tropical wave axis is along 94W N of 12N, moving W around 10 kt. The wave energy in the form of related vorticity is contributing to a developing cyclonic broad gyre of low pressure S of the Gulf of Tehuantepec to the monsoon trough region. Latest satellite imagery shows large clusters of scattered moderate to strong convection within 180 nm W of the wave axis N of 13N to inland the coast of southeastern Mexico near 16N. INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from NW Colombia to 11N92W to 08N105W to 13N113W to 15N125W. It continues from 15N134W beyond 11N140W. Scattered moderate isolated strong convection is within 120 nm N of the axis between 91W and 95W, and within 180 nm S of the axis between 91W and 97W. Scattered moderate convection is within 120 nm N of the axis between 130W and 135W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please refer to the special features section for more information about Tropical Storm Norma. Gulf of California...Mainly moderate southerly winds associated with Tropical Storm Norma are observed across the Gulf waters S OF 25N where combined seas are maxing up to around 7 ft this morning. These winds are forecast to diminish to gentle southerly winds by this evening, with seas lowering to below 6 ft. The winds will become gentle there on Tuesday, with seas continuing to lower into Wednesday. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Light to gentle winds will continue N of the monsoon trough through Thursday when the monsoon trough will lift further northward. Moderate SW winds and 4 to 7 ft seas will prevail S of the monsoon trough axis through Thu. REMAINDER OF THE AREA... Please refer to the special features section for details on Tropical Storm Otis. A NW to SE orientated surface ridge separates the areas of cyclonic wind flow that are around the tropical cyclones. Long period NW swell in the form of 8 to 9 ft seas is forecast to arrive near 30N122W on Tuesday in the early afternoon, and continue to propagate southward, and be to the NW of the line from 30N118W to 26N120W to 26N125W to 16N125W to 16N140W early on Wednesday morning, and then to the NW of the line from 30N116W to 22N118W to 15N130W to 15N140W early on Thursday morning. $$ Aguirre