000 AXPZ20 KNHC 242140 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2140 UTC Fri May 24 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 2130 UTC. ...SPECIAL FEATURES... ...Excessive Rainfall Over Central America... A large cyclonic gyre that is typical for this time of the year, called a Central American Gyre, will continue bringing abundant moisture and heavy rainfall across portions of Central America during the next few days. Life-threatening flash flooding and mudslides will be possible in areas of mountainous terrain. Please refer to your local meteorological service for more details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from near 08.5N83W to 1008 mb low pressure near 11.5N87W to 09N98W to 10N107W to 08N115W. The ITCZ continues from 08N115W to 1010 mb low pressure near 09N126W to 06N130W to beyond 06N140W. Scattered moderate and isolated strong convection is noted from 04N to 09N between 84W and 89W and within 240 nm north of the trough between 93W and 99W. Scattered moderate convection is occurring within 180 nm south of the trough between 94W and 107W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A recent scatterometer pass over the Baja California Sur offshore waters showed gentle to moderate NW flow as the pressure gradient has relaxed today. The NW swell impacting the Baja California waters has continued decaying, and seas are likely 8-9 ft over the forecast waters. A high pressure ridge is expected to build southeastward over the offshore waters Sat night and Sun, resulting in fresh winds off the southern tip of Baja California Sur into early next week. Gulf of California: Scatterometer data from this afternoon showed gentle NW flow over the central and southern Gulf of California. A cold front is expected to approach Baja California Norte Sat and Sat night. SW gap winds will strengthen ahead of the front across the northern Gulf with strong to near gale force winds and seas to 8 ft north of 29.5N Sat night and Sun. Strong SW gap winds will persist into Sun night, then shift to NW by early Mon as the cold front crosses the northern Gulf and weakens. Then, wind speeds over the Gulf will diminish through mid week. Gulf of Tehuantepec: Fresh to strong northerly winds will pulse across the Gulf of Tehuantepec region during the overnight and early morning hours this weekend with the assistance of the nocturnal drainage flow. Seas will build to 8-9 ft with each short-lived gap wind event, highest on Sun morning. Fresh winds early on Mon will diminish to gentle speeds through mid week. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Please read the Special Features section for more information about the Central American Gyre, which will bring heavy rain to parts of Central America and the adjacent offshore waters. As the monsoon trough lifts northward in association with the Central American Gyre, southerly monsoon flow will prevail over the forecast waters and likely strengthen early next week. Seas 8 ft or less this weekend will build to 8-11 ft early next week as SW swell mixes with locally generated wind waves from strengthening monsoon flow. Some gradual tropical development of a nearby low pressure trough over the far eastern Pacific is possible while it moves little during the next few days. REMAINDER OF THE AREA... Decaying NW swell over the northern forecast waters is producing 8-9 ft seas roughly north of 25N between 120W and 133W based on earlier altimeter data and recent model guidance. This swell will continue subsiding through tonight with seas falling below 8 ft on Sat. Recent scatterometer data highlighted fresh NE trade winds between the ITCZ and a high pressure ridge extending southeast across the northern waters. These trades will gradually diminish and seas will subside this weekend as the ridge weakens north of the area. A pulse of SW swell across the southern forecast waters is producing seas to 8 ft south of the Equator between 100W and 115W. Another SW swell event will commence over the southern waters on Sun and propagate northward through early next week. This will result in a large area of seas 8 ft or greater south of 10N between 90W and 125W by Tue. $$ Reinhart