000 AXPZ20 KNHC 221541 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Fri Sep 22 2017 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 0600 UTC surface analysis and satellite imagery through 0830 UTC. ...SPECIAL FEATURES... A broad elongated area of monsoonal low pressure persists along the southwest coast of Mexico and coastal waters. A weak poorly defined cyclonic circulation is evident from Metsat data within this broad area near 17N104W, with an estimated pressure of 1007 mb. An large area of fresh to locally strong SW monsoon winds is evident from scatterometer data, roughly from 09N to 13N between 100W AND 122W. Model guidance indicates this area of monsoonal flow has the potential to develop into a tropical cyclone as it lifts slowly northward. Convergent monsoon winds are generating widespread active convection along the coast of Mexico between Cabo Corrientes and Chiapas, with heavy rains likely to persist in this area several more days. ..INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough stretches across the entire basin from Panama near 08N78W to 16N100W to low pres near 17N104W 1007 mb to 12N120W to 10N140W. Scattered moderate to strong convection is within 60 nm of a line from 08N89W to 13N95W. Scattered moderate isolated strong convection within 75 nm s of trough east of 83W. Scattered moderate convection within 90 nm s of trough between 112W and 133W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A weakening cold front extends across northern Baja California into the Gulf of California. Scatterometer data at 0500 UTC showed fresh to strong SW winds ahead of the front north of 30N in the Gulf of California, and fresh northerly winds behind the front. Expect the front to push further south and weaken through early Sat, then dissipate by Sat afternoon. High pressure will build north of 25N behind the front through Sun, with NW winds increasing slightly west of Baja California Norte. Elsewhere, the possible development of low pressure along the southern coast of Mexico will increase winds and seas between 101W and 117W the next few days. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... An active monsoon trough along the coast of Central America from Guatemala to Panama will remain focus for widespread convection over the coastal waters the next few days. Expect SW winds south of the trough to gradually become 20-25 knots through Saturday. Farther south, gentle to moderate south to southwest winds will persist south of 05N through the weekend. Long period SE swell from the Southern Hemisphere will maintain seas west of Ecuador and south of 02S around 7-8 ft the rest of today. REMAINDER OF THE AREA... NW swell generated by strong N to NW winds north of the area are producing combined seas to 8 ft north of 29N between 118W and 122W. This area of combined seas will slowly subside during the next 24 hours. High pressure centered well N of the area and lower pressure associated with the monsoon trough will maintain moderate to occasionally fresh trade winds west of 120W through the weekend. $$ Mundell