000 AXPZ20 KNHC 302124 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2027 UTC Mon Sep 30 2019 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 1800 UTC surface analysis and satellite imagery through 2100 UTC. ...SPECIAL FEATURES... Tropical Storm Narda is centered near 24.0N 107.4W at 30/2100 UTC moving NW at 14 kt. Estimated minimum central pressure is 998 mb. Maximum sustained wind speed is 45 kt with gusts to 55 kt. Numerous moderate to strong convection is noted on the west semicircle of Narda, particularly from 22N to 25N between 107W AND 109W. On the forecast track, the center of Narda will move along the coast of northwestern mainland Mexico through Tuesday night. Little change in strength is expected this evening, but Narda should begin to weaken later tonight and Tuesday as it intersects with land. Narda is expected to produce rainfall amounts of 2 to 4 inches in Sinaloa, 1 to 2 inches in Sonora, and up to 1 inch in Baja California Sur. This rainfall will cause life-threatening flash floods and mudslides, especially in mountainous terrain. Swells generated by Narda are affecting portions of the coast of southwestern Mexico. These swells are expected to spread northward and will likely cause life- threatening surf and rip current conditions along the west coast of mainland Mexico, along the east coast of Baja California Sur, and in Las Tres Marias Islands. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCMEP1/WTPZ21 KNHC for more details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from near 07N78W to 10N90W to 15N95W, then resumes near 16N101W to 12N115W to 16N126W to 1008 mb low pressure near 12N136W to 12N140W. Scattered moderate isolated strong convection is from 11N to 17N between 100W and 108W, from 10N to 13N between 108W and 115W, and 08N to 14N W of 136W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features section above for information about Tropical Storm Narda. Tropical Storm conditions are expected across the southern Gulf of California tonight and Tue, and across the central part of the Gulf on Tue. Elsewhere, a weak ridge dominates the offshore forecast waters of Baja California. The pressure gradient between the ridge and lower pressures over the SW of United States is resulting in fresh to locally strong NW winds N of Punta Eugenia, with seas to 8 ft. These marine conditions will persist through Tue night. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Generally moderate W to NW winds prevail north of Costa Rica to the Tehuantepec region, while moderate SW to W winds are noted south of Panama and off the coast of Colombia. Seas of 8 ft in long period SW swell persist across the waters off Guatemala, El Salvador, and Nicaragua with seas in the 5 to 7 ft range elsewhere across the region. Seas will subside below 8 ft by tonight. Fresh to locally strong SW monsoon flow will resume on Tue between Central America and the Galapagos Islands, with seas building to 8 to 9 ft offshore of Costa Rica and Panama. REMAINDER OF THE AREA... High pressure located well NW of the forecast area near 38N140W extends a ridge across the northern forecast waters, mainly N of 20N W of 120W. Scatterometer data showed moderate to fresh NE winds north of 24N and west of 125W, with corresponding altimeter data indicating seas were 7 to 8 ft in this region. The pressure gradient between the ridge and lower pressure in the vicinity of the monsoon trough will result in moderate to fresh winds NE-E winds N of the monsoon trough on Tue, with fresh to locally strong NE-E winds on Wed as a couple of low pressure systems remain along the monsoon trough. Fresh SW winds are blowing S and within about 120 nm of the monsoon trough between 107W and 115W with seas to 9 ft. Scatterometer and altimeter data confirmed the presence of these marine conditions. $$ GR