000 AXPZ20 KNHC 090402 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Thu Sep 9 2021 Tropical Weather Discussion for the eastern Pacific Ocean from 03.4S to 30N, east of 120W including the Gulf of California, and from the Equator to 30N, between 120W and 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 0345 UTC. ...SPECIAL FEATURES... Tropical Storm Olaf is centered near 20.0N 108.0W 1000 mb at 8 PM PDT moving NNW at 6 kt. Estimated minimum central pressure is 1002 mb. Maximum sustained wind speed is 45 kt with gusts to 55 kt. Satellite imagery reveals that Olaf is gradually strengthening as banding features are becoming more pronounced and deep convection is increasing as well. This convection is observed as the numerous moderate to strong type intensity within 150 nm of the center in the NE quadrant. Scattered moderate to isolated strong convection is within 90 nm of the center in the SW quadrant and in an outer rainband that within 30 nm of a line from 18N105W to 19N106W to 21N107W. Scattered moderate convection is within 120 nm of the center in the SE quadrant. With Olaf strengthening, seas will also build with it. Presently maximum seas reach a peak of 15 ft, but are forecast to build to near 24 ft on Thu through Fri as Olaf approaches southern Baja California. Swells generated by Ola will affect portions of the coasts of Baja California Sur and Sinaloa by Thu, spreading northward along the west coast of Baja California Sur through Fri. Additional strengthening is forecast during the next day or so, and Olaf could be near hurricane strength by late Thu. The storm is expected to begin weakening on Fri. Olaf is expected to produce total rainfall amounts of 3 to 6 inches with maximum amounts of 10 inches across portions of far southern Baja California Sur Thu through Fri. This rainfall may trigger flash flooding and mudslides. Please read the latest NWS High Seas Forecast issued by the National Hurricane Center at website https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml and the latest NHC Public Advisory at https://www.nhc.noaa.gov/text/MIATCPEP5.shtml and Forecast/ Advisory at https://www.nhc.noaa.gov/text/MIATCMEP5.shtml for more details. ...TROPICAL WAVES... A tropical wave has its axis along 96W north of 05N to inland southeastern Mexico. It is moving westward at 10 kt. Scattered moderate convection is within 60 nm east of the wave axis from 10N-13N, and inland Mexico near the northern part of the wave. The tropical wave that previously was along 102W from 05N to 18N is no longer evident as it has been absorbed into the circulation of Olaf. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from just offshore northwestern Colombia to across southern Panama and northern Costa Rica to 11N86W to 11N97W to 12N110W and to 09N125W. It resumes at 16N128W to low pressure at 16N136W and to 15N140W. Aside from the convection associated with Tropical Storm Olaf and the tropical wave, scattered moderate to isolated strong convection is noted from 07N to 10N between 86W-90W. Scattered moderate convection is within 60 nm south of the trough between 84W-95W, and within 30 nm of the trough between 95W-97W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features section above for details on Tropical Storm Olaf. A weak 1011 mb low is centered near 25N126W. A trough extends from it to 245N131W. No convection is occurring with this low as it is surrounded by a very dry and stable environment. Latest ASCAT data showed gentle to moderate northwest winds off the Baja California peninsula, except for moderate to fresh winds within about 180 nm west of Baja California Norte. Seas over these waters are in the 4-5 ft range in long-period south swell. Latest ASCAT data revealed light to gentle variable winds across the Gulf of California. Seas are less than 3 ft, except 3-4 ft just south of the entrance to the Gulf. Scattered moderate to isolated strong convection occurring in an outer rain band from Olaf is along and just inland the coast from Jalisco to Nayarit. Tropical Storm Olaf is forecast to turn toward the west- northwest by Friday night, followed by a turn toward the west on Sat. On the forecast track, the center of Olaf will move just to the southwest of southern Baja California Sur on Thu and Fri. Additional strengthening is forecast during the next day or so, and Olaf could be near hurricane strength by late Thu. The storm is expected to begin weakening on Fri. In the Gulf of California, light and variable winds will continue through Thu night, then become gentle to moderate southeast winds through Sat. Light to gentle winds will continue across southern Mexico. Fresh to strong gaps winds are expected to develop across the Gulf of Tehuantepec beginning late Thu night and continue into the upcoming weekend. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, and WITHIN 750 NM OF ECUADOR... Moderate south to southwesterly winds is noted south of the monsoon trough with light and variable winds north of the monsoon trough. Seas are 3-6 ft in the Central American offshore waters and 6-7 ft seas off of Ecuador and the Galapagos Islands. Satellite imagery shows scattered showers and thunderstorms along and just offshore the coast of Costa Rica and Panama. Seas are 3-6 ft in the Central American offshore waters, except for higher seas of 5-7 ft over the waters between Ecuador and the Galapagos Islands due to a southwest swell. These seas will build to 6-8 ft due to a southwest swell beginning Thu. Winds in Papagayo region will increase to fresh speeds Sat. Moderate to fresh southwest winds are expected along the offshore waters of Costa Rica, Panama, Colombia, Ecuador and Galapagos Islands through the weekend. Strong south to southwest winds are expected over the offshore waters of Guatemala and El Salvador late Sat through late Sun as low pressure develops south of the southern coast of Mexico. Seas in these waters will remain in the 6-7 ft range, except near 8 ft seas in the region west of Ecuador. Seas offshore Guatemala, Honduras and El Salvador are expected to build to possibly 9 ft during Sat and Sat night due to the expected strong south to southwest winds combining with southwest swell that will be propagating through those same offshore waters. REMAINDER OF THE AREA... Broad high pressure dominates the waters north of the monsoon trough. The gradient between the high and the lower pressure to the south in the monsoon trough region is allowing for moderate to fresh north-northeast winds and seas 7 ft south of 21N and west of 134W. Moderate southerly winds remain south of the monsoon trough, with seas to 7 ft. Seas to 8 ft due to a southwest swell continue south of the Equator and west of the Galapagos Islands tonight before another set of southwest swell begins to propagate through the waters west of the Galapagos Islands from Thu through the upcoming weekend. Seas will range between 8-9 ft through early next week. $$ Aguirre