000 AXPZ20 KNHC 260929 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Tue May 26 2020 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 0915 UTC. ...TROPICAL WAVES... The axis of a tropical wave is analyzed along 97W from 04N to 15N, moving westward at 10-15 kt. This wave is embedded in a moistening surrounding atmospheric environment. Scattered moderate to isolated strong convection is occurring where the wave crosses the monsoon trough. Isolated showers and thunderstorms are along and within 30 nm of the axis from 05N to 09N. The southern part of a western Caribbean tropical wave is along 83W and north of north of 05N, moving westward at 15 kt. Scattered moderate to strong convection is near the axis from 05N to 08N between 83W-89W. Scattered moderate convection is over southern Costa Rica. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from a 1009 mb low over northwestern Colombia near 11N73W, southwestward to the coast at 07N78W and continues to 08N84W to 11N93W to 11N100W to a 1008 mb low near 09N106W, then to 10N120W to 10N130W and to 09N135W, where over night scatterometer indicates that it transitions to the ITCZ to beyond the area at 09N140W. Scattered moderate to strong convection is within 120 nm south of the trough between 84W-88W and within 60 nm north of the trough between 97W-102W. Scattered moderate to isolated strong convection is within 120 nm south of the trough between 90W-95W, also between 107W-111W and within 120 nm north of the trough between 107W-109W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A ridge extends from high pressure centered north of the area near 34N139W southeastward toward the Revillagigedo Islands. Gentle to moderate northwest winds offshore of Baja California as were highlighted by ASCAT data from Mon afternoon are due to the pressure gradient between the ridge and deep low pressure over inland Mexico. Wave heights offshore Baja California are in the 4-6 ft range. Light and variable winds remain over the Gulf of California, where wave heights are low, in the 0-2 range. The high pressure will weaken through Thu, with little change to present marine conditions. Southwest swell will build seas slightly over the waters south of Tehuantepec Wed through late this week. Agricultural fires in Mexico will continue to produce hazy skies near the coast of southern Mexico, but clearing with time. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Overnight ASCAT data showed gentle to moderate south to southwest winds south of the monsoon trough, with light to gentle winds elsewhere. Wave heights due to a southwest swell are in the range of 4-6 ft per latest altimeter data passes. Gentle to moderate monsoon flow will prevail over the next few days. Long-period southwest swell will continue impacting the offshore waters through at least Wed. with wave heights building to near 8 ft SW of the Galapagos Islands by that time. A broad area of low pressure is expected to form later this week offshore of southern Mexico, Guatemala, and El Salvador. Environmental conditions appear conducive for gradual development of this system, and a tropical cyclone could form late this week or this weekend while it moves little or drifts northward. Expect increasing winds and seas, along with gusty showers and thunderstorms, to begin to increase in coverage over most of the offshore waters by Thu. REMAINDER OF THE AREA... A ridge extends from high pressure of 1025 mb centered north of the area near 34N139W southeastward across the northern waters. Gentle to moderate northeast winds continue between this ridge and the monsoon trough/ITCZ per recent scatterometer data. Increasing clusters of numerous moderate to isolated strong convection are noted within 270 nm in the SW quadrant of a nearly stationary 1008 mb low that is along the monsoon trough near 09N106W. Overnight ASCAT data passes indicate moderate to fresh winds within about 300 nm in the southern semicircle of the low. Elsewhere, moderate, to at times fresh, south to southwest winds are south of the monsoon trough between 92W-98W and also between 102W-112W. Farther south, cross-equatorial south to southwest swell is producing wave heights in the range of 7-10 ft south of 08N and between 99W-120W. This swell will continue to propagate northeastward through Wed before it gradually begins to decay. High pressure will weaken over the northern waters as an upper- level pressure system induces a surface trough/low near 26N130W by Wed morning. Expect fresh winds along with wave heights building to 8 ft northwest of the low Wed into Thu as it remains nearly stationary. The low near 09N106W will drift northeastward along the monsoon trough over the next couple days, with fresh winds and locally higher wave heights expected south and southeast of the low center. Scattered to numerous showers and thunderstorms are expected with the low as it moves into through a very moist and unstable atmospheric environment. $$ Aguirre