000 AXPZ20 KNHC 310236 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Wed May 31 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 0000 UTC surface analysis and satellite imagery through 0215 UTC. ...SPECIAL FEATURES... An area of broad low pressure is present to the south of southeastern Mexico, with the associated low pressure center of pressure 1009 mb located near 14N98W. Clusters of numerous showers and thunderstorms are observed mainly in the eastern and southern semicircles of the low pressure, and are described as the scattered to strong type within 30 nm either side of a line from 12.5N92W to 14N93W to 15.5N95W. Scattered moderate/isolated strong convection is noted to the south and southwest of the low center from 08N to 12N between 95W and 99W, and also from 09N to 13N between 99W and 103W. Last visible imagery revealed increasing low clouds rotating in a cyclonic fashion into the convection from near 11N to 16.5N between 100W and 106W. Abundant moisture is present within the environment surrounding this broad low pressure system as it continues to pull in additional moisture from a rather active background monsoonal flow to its south. This synoptic set-up should be very favorable very active weather to continue in the form of additional shower and thunderstorm activity during the remainder of the week. In addition, expect clusters of heavy showers and thunderstorms to persist along and offshore of the coast of southeastern Mexico, from the Tehuantepec region to near the Acapulco are also during the rest of the week. This activity is likely to contain locally heavy rainfall with the possibility of life-threatening flash floods and mudslides. The low pressure center may possibly develop into a tropical cyclone as it slowly moves northward towards the coast of Mexico through the week. ...TROPICAL WAVES... The southern portion of a western Caribbean Sea tropical wave axis has moved into the far eastern portion of the area to along 79W and north of 03N moving west at 10 to 15 kt. Only isolated showers and thunderstorms are noted within 60 nm of the axis. The wave is expected to help increase shower and thunderstorm activity over much of Honduras, Costa Rica and Panama through the next 48 hours or so as it interacts with the monsoon trough eastern segment situated across those geographic areas of central America. It should also enhance scattered showers and thunderstorms presently occurring south of Costa Rica and northern Panama within 60 nm either side of a line from 06N82W to 07N87W. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The Monsoon Trough axis extends from 08N79W to 13N91W to the low pressure near 14N98W 1008 mb to 10N110W to 08N121W, where scatterometer data indicated the ITCZ axis continues to 08N130W to 06N140W. Scattered moderate isolated strong convection is noted within 120 nm south of the axis between 103W and 106W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Moderate to fresh northwest winds will continue west of the Baja Peninsula through Friday, resulting from the pressure gradient between high pressure to the west and surface troughs in Baja California and mainland Mexico. Expect stronger northwest winds off the coast of southern California, resulting in combined seas of 7 to 9 ft as is presently occurring north of 29N between 120W and 125W. This swell will propagate southward to near 27N between 119W and 123W by Wednesday afternoon before decaying to less than 8 ft around the time of Thursday afternoon. Light to gentle southeast to south winds over the Gulf of California today will become gentle to moderate winds tonight and Wednesday. Seas will be 1 to 2 ft, except 3 to 4 ft over the entrance to the Gulf of California. Otherwise, mainly light to gentle winds and seas of 5 to 7 ft will continue over the Mexican offshore waters south of Baja California. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Moist southerly flow associated with the monsoon trough will continue to support scattered showers and thunderstorms mainly north of 04N. Some of this activity may contain strong gusty winds and produce rough seas. Light to gentle winds will prevail north of the trough axis with 4 to 6 ft seas. Mainly moderate south to southwest winds are expected south of the trough axis with seas of 5 to 7 ft. REMAINDER OF THE AREA... A 1024 mb high is analyzed near 28N135W with a ridge stretching southeastward to 25N125W and to near 19N116W. High pressure covers the area to the north of 15N and west of about 115W. The associated pressure gradient between the ridge and lower pressure to the south in the deep tropics is supporting fresh northeast trades from 07N to 15N west of 133W, with seas of 7 to 9 ft in mixed northeast and southeast swell. This area will gradually shrink through Thursday as the ridge retreats westward. Gentle to moderate trade winds will continue over the remainder of the northwestern waters through Wednesday with 5 to 6 ft seas. Fresh northwest winds are forecast to develop north of 27N and east of 125W late tonight as the pressure gradient between low pressure deepening inland over the SW United States and high pressure over the northwest and north/central forecast waters tightens. These winds will support 7 to 9 ft seas over that area through Wednesday evening before subsiding to less than 8 ft on Thursday. $$ Aguirre