000 AXPZ20 KNHC 261558 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Mon Sep 26 2016 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... Tropical Storm Roslyn is centered near 17.0N 119.4W at 26/1500Z, or about 645 nm WSW of the southern tip of the Baja California Peninsula, moving NNE or 015 degrees at 4 kt. A turn toward the northeast with some increase in forward speed is expected later today. Estimated minimum central pressure is 1005 mb. Maximum sustained wind speed is 35 kt with gusts to 45 kt. Little change in strength is forecast during the next day or so. Weakening should begin by Tuesday night. Currently, a cluster of moderate to isolated strong convection is within about 180 nm E semicircle of center. Scattered moderate isolated strong is elsewhere in a band within 90 nm SE of a line from 16N118W to 14N119W to 13N121W. On the forecast track, Roslyn is expected to remain west of the offshore forecast zones. It is forecast to maintain minimum tropical storm strength through Tue morning, then lose tropical characteristics and become a remnant low by Wednesday morning near 21.0N 117.2W at 28/1200 UTC. Please, refer to the latest NHC forecast/advisory under AWIPS/WMO headers WTPZ23 KNHC/TCMEP3, or visit the NHC website at http://hurricanes.gov for additional details. A new tropical depression has formed near 140W. T.D.Nineteen-E is centered near 11.6N 139.6W at 26/1500Z, or about 1015 nm ESE of HILO Hawaii, moving NW or 305 degrees at 4 kt. A turn toward the north is expected today, followed by a turn toward the north-northeast on Tuesday, with the center remaining E of 140W through Thursday. Estimated minimum central pressure is 1005 mb. Maximum sustained wind speed is 30 kt with gusts to 40 kt. A custer of moderate to isolated strong convection is within about 60 nm NE semicircle. Scattered moderate to isolated strong convection is elsewhere from 09N to 13N W of 137W. T.D.Nineteen-E is forecast to gradual strengthen during the next couple of days. The intensity forecast shows this tropical cyclone reaching tropical storm force at 27/0000 UTC. Please, refer to the latest NHC forecast/advisory under AWIPS/WMO headers WTPZ24KNHC/TCMEP4, or visit the NHC website at http://hurricanes.gov for additional details. ...TROPICAL WAVE... A tropical wave previously located near 99W is no longer discernible on 700 mb streamlines analysis and surface data. Instead, a surface trough is analyzed across the Gulf of Tehuantepec from 08N95W to 16N94.5W. A 5-day TPW loop and 700 mb streamlines analysis indicate abundant moisture between 93W-101W with a trough persisting across the Gulf of tehuantepec region. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends across the far SW Caribbean and central Costa Rica into the EPAC near 09N85W to 12N95W to 09N110W, then it resumes just SW of Roslyn near 12N123W, and continues to 12N134W to T.D. Nineteen near 11.5N 139.5W. Scattered moderate convection is noted from 05N-07N between 96W-91W...and from 07N- 09N between 94-99W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A sub-tropical ridge axis extends from NW to SE across the offshore zones W of the Baja California Peninsula to near 24N117W. Light to gentle NW winds are observed W of the Baja California Peninsula. Gentle to occasionally moderate flow expected elsewhere along the Pacific coast of Mexico through tonight. Moderate to fresh winds on the eastern side of tropical cyclone Roslyn are expected to affect the extreme western waters of offshore zones PMZ015 and PMZ013 from Tue night through Thursday morning. Building high pressure over the Great Basin to the north of the region will allow a brief surge of fresh northerly winds across the northern Gulf of California through late Tuesday morning. A cold front is forecast to move across the Gulf of Mexico waters tonight followed by a stronger cold front on Thursday. High pressure behind the fronts will likely induce the first Gulf of Tehuantepec gap wind event of the season by Wednesday night into Thursday morning. Marine guidance suggests Northerly winds of 20-30 kt with seas up to 9-10 ft by Thursday. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Mainly light and variable winds are noted north of the monsoon trough while gentle to locally moderate south to southwest flow is expected south of monsoon trough the middle of the week. Combined seas of 3-6 ft, primarily in long-period southwest swell, are expected through the middle of the week. REMAINDER OF THE AREA... A 1024 mb high pressure located near 35N139W extends a ridge across the north waters, particularly N of 20N. Between 10N-20N W of 110W there are two tropical cyclones. Please, see special features for details. $$ GR