574 AXPZ20 KNHC 291606 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1558 UTC Sat Sep 29 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 1200 UTC surface analysis and satellite imagery through 1500 UTC. ...SPECIAL FEATURES... Hurricane Rosa centered near 20.5N 118.4W at 29/1500 UTC or 470 nm SSW of Punta Eugenia Mexico moving N at 10 kt. Estimated minimum central pressure is 968 mb. Maximum sustained wind speed is 90 kt with gusts to 110 kt. Scattered to numerous convection is within 120 nm of the center of Rosa. On the forecast track, the center of Rosa will be approaching central and northern Baja California on Monday as a tropical storm. Swells generated by Rosa will affect portions of the coasts of southwestern Mexico, most of the Baja California Peninsula, and southern California during this weekend. These swells are likely to cause life-threatening surf and rip current conditions. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCPEP5/WTPZ35 KNHC for more details. Newly formed Tropical Storm Sergio Special is centered near 12.4N 102.1W at 29/1530 UTC or 300 nm SSW of Acapulco Mexico moving WNW at 11 kt. Estimated minimum central pressure is 1005 mb. Maximum sustained wind speed is 35 kt with gusts to 45 kt. Numerous moderate to strong convection is noted within 120 nm of the center of the storm. Sergio is expected to intensify further to hurricane strength through early Mon as it moves west- northwest. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCPEP1/WTPZ31 KNHC for more details. ...TROPICAL WAVES... A tropical wave extends along 88W north of 04N into the Gulf of Fonseca. No significant convection is noted at this time. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 11N86W to the newly formed Tropical Storms Sergio. The intertropical convergence zone reaches from 07N132W to 05N140W. No significant convection other than within 120 nm of Sergio. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See Special Features above for information on Hurricane Rosa and Tropical Storm Sergio. Recent scatterometer data indicate gentle to moderate NW flow west of the Baja California Norte while mainly light to gentle winds are prevailing west of Baja California Sur. Winds and seas will begin to gradually increase across the offshore forecast waters mainly W of 110W tonight as Rosa approaches the area. Tropical Storm conditions are expected Sun night and Mon. In the Gulf of California, gentle to moderate 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, fresh to strong northerly winds are expected with seas building to 9 ft tonight into early Sun Mon. These condition will persist on Sun night into early Mon morning. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... The monsoon trough will meander between 09N and 12N through Tue, with gentle to moderate winds expected on either side of the trough axis. Moderate to fresh E nocturnal drainage flow is expected in the Gulf of Papagayo through Sun night. REMAINDER OF THE AREA... See Special Features above for information on Hurricane Rosa. A weak ridge dominates the NW forecast waters producing gentle to moderate N of 23N W of 120W, and moderate to fresh trades S of 23N. A weak cold front will sweep across the waters north of 27N through early next week, accompanied by a W to NW wind shift. NW swell may propagate into the N central waters early next week. $$ Christensen/Rubio