528 AXPZ20 KNHC 280348 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Fri Sep 28 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 0300 UTC. ...SPECIAL FEATURES... Hurricane Rosa centered near 16.9N 116.7W at 0300 UTC or 495 nm SW of the southern tip of Baja California moving W at 8 kt. Estimated minimum central pressure is 940 mb. Maximum sustained winds are 125 kt with gusts to 150 kt. Numerous moderate to strong convection is within 180 nm of the center. Scattered moderate isolated strong convection is elsewhere between 300 nm of the eye. Swells generated by Rosa will affect western Mexico, including the Baja California peninsula, and southern California during the weekend, and may cause life-threatening surf and rip current conditions. Please consult forecasts from your local weather office. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCMEP5/WTPZ25 KNHC for more details. An 1007 mb area of low pressure near 11N97W is poorly organized with a broad cyclonic circulation. Scattered moderate isolated strong convection is from 10N to 15N between 90W and 101W. Fresh easterly winds and seas to 9 ft are in the N semicircle of the low within 180 nm. This low will drift WNW and gradually become better organized through the weekend. It has a medium potential for tropical cyclone development within the next 48 hours. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 11N86W to low pressure near 11N97W to 12N104W, then resumes from 13N123W to 09N134W. The ITCZ axis extends from 09N134W to 10N140W. Scattered moderate isolated strong convection is from 06N to 12N between 85W and 98W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See the Special Features paragraph above for information on Hurricane Rosa and the tropical low near 11N97W. A ridge along 27N will retreat W of the area ahead of Hurricane Rosa. Gentle to moderate NW flow west of the Baja peninsula will become northerly on Sat, with marine conditions deteriorating across southern waters by Sat night as Rosa approaches the area, with hurricane or tropical storm conditions spreading NE into the waters W of Baja California Norte through early next week. In the Gulf of California, light to gentle southerly winds are expected through Sun night. The southerly flow will increase to near gale force N of 27N thereafter, with tropical storm conditions possible N of 29N Mon night and Tue from Rosa. In the Gulf of Tehuantepec, nocturnal offshore northerly flow will pulse to fresh to strong through the next several days with seas briefly building to 8 ft during the strongest winds. The tropical low discussed above is forecast to move by S of the area through the end of the week. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... In the Gulf of Papagayo, moderate to locally fresh E nocturnal drainage flow is expected through Sun night, with seas occasionally building up to 7 ft. Elsewhere, mainly gentle and variable winds are forecast N of the monsoon trough, which will meander between 09N and 12N, with moderate SW flow S of the trough, for the next several days. Seas will be mainly 4 to 6 ft. REMAINDER OF THE AREA... See the Special Features paragraph above for information on Hurricane Rosa. A broad ridge extends along 27N with gentle anticyclonic flow N of 23N, and moderate to fresh flow S of 23N. A series of weak cold fronts or troughs will sweep east across the far NW waters through the upcoming weekend, accompanied by a moderate W to NW wind shift. Seas will be 4-7 ft in mixed swell through Mon. NW swell may propagate into the N central waters early next week. $$ Mundell