000 AXPZ20 KNHC 280245 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Wed Sep 28 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 0000 UTC surface analysis and satellite imagery through 0215 UTC. ...SPECIAL FEATURES... Tropical Storm Roslyn is centered at 19.5 115.9W at 28/0300Z, or about 391 nm west-southwest of the southern tip of the Baja California Peninsula, moving northeast or 040 degrees at 8 kt. The estimated minimum central pressure is 1004 mb. Maximum sustained winds have diminished to 35 kt with gusts to 45 kt. Latest satellite imagery shows that Roslyn remains a sheared tropical cyclone with the low- level center removed well to the south of the remaining convection due to moderate to southwesterly winds aloft. The imagery shows the remaining plume of scattered moderate convection between 90 nm and 210 nm of the center in the north quadrant. Roslyn is forecast to weaken to a tropical depression late tonight into Wednesday morning, then to a post- tropical remnant low by early Wed afternoon...then begin to track to the northwest later on Wednesday afternoon and through Thursday while dissipating. 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. Tropical Storm Ulika is located in the far western edge of the discussion area and high seas forecast area near 13.3N 139.1W at 28/0300Z, or about 995 nm east-southeast of Hilo Hawaii, moving northeast or 045 degrees at 6 kt. The estimated minimum central pressure is 997 mb. Maximum sustained winds have increased to 55 kt with gusts to 60 kt. Latest satellite imagery shows that Ulika is becoming better during evening with tightly coiled banding features around a small central dense overcast (CDO) feature. Scattered strong convection is within 30 nm of the center. Scattered moderate isolated strong convection is within 90 nm of the center in the southeast quadrant. Scattered moderate within 90 nm of the center in the northeast quadrant. 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. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from northwest Panama at 10N84W to 10N90W to 12N97W to 12.5N104W to low pressure near 12N107W 1008 mb to 08N115W. It resumes at 13N117W to 12N125W to 14N129W to 14N135W. Scattered moderate isolated strong convection is observed within 180 nm south of the axis between 80W and 85W, within 60 nm of the axis between 127W and 129W and between 132W and 134W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A northwest to southeast oriented surface trough is analyzed from 11N96W to near Acapulco Mexico. Scattered moderate to isolated strong convection is noted from 09N to 16N between 98W and 103W. Relatively weak high pressure covers the area to the north of the tropical cyclones Rosyln and Ulika. The associated gradient is producing light to gentle N to NE winds to the west of the Baja Peninsula, with the exception of waters near and around the Rosyln. Pockets of diminishing showers and thunderstorms and strong E winds and combined seas of 8 to 11 ft will expand northeastward across the waters generally from 18N to 23N W of 114.5W through Wednesday night as Tropical Storm Roslyn continues northward while weakening. The subtropical ridge will extend from 29N120W to 20N106W on Fri with gentle N flow returning. The pressure gradient will tighten Fri. Moderate to fresh NW winds and 5 to 8 ft seas will prevail W of Baja Sat and Sun. Light to gentle NW winds are expected across the entire Gulf of California through Thu. Light and variable winds expected on Fri across the far northern gulf waters. Strong drainage flow will pulse across the Gulf of Tehuantepec late Thursday night into Friday morning. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Light to gentle S winds expected N of the monsoon trough, while gentle to locally moderate S to SW flow is expected to the south of of the monsoon trough through the upcoming weekend. Combined seas of 3 to 6 ft primarily in long-period SW swell are expected this week. REMAINDER OF THE AREA... As Ulika pulls off to the west of 140W Thursday night and Roslyn degrades to a remnant low, the subtropical ridge will strengthen slightly. This will tighten the gradient over the northwest portion of the area with northeast to east moderate winds with seas of 6 to 7 ft expected there at that time. Gentle to moderate NE winds with seas of 5 to 6 ft are expected elsewhere north of the monsoon trough not affected by Roslyn or Ulika. Moderate to occasionally fresh southerly flow and 6 to 7 ft seas will dominate south of the monsoon trough for at least the next couple of days. $$ AGUIRRE