000 AXPZ20 KNHC 060908 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 534 UTC Tue Jun 6 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 0900 UTC. ...TROPICAL WAVES... A tropical wave reaches from 03N87W to 15N87W, moving west at 25 to 30 kt. TPW satellite imagery shows this wave is embedded in a large area of deep moisture. Scattered moderate and isolated strong convection is found from 05N to 13N between 86W and 88W. Another tropical wave reaches from 08N104W to 15N104W, moving west at 5 to 10 kt. A 0354Z scatterometer pass suggests weak low pressure has developed where this wave crosses the monsoon trough. This wave is situated on the leading edge of an area of deep layer moisture. Scattered moderate and isolated strong convection is present from 04N to 14N between 99W and 107W. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 10N78W to 09N81W to 11N85W, then resumes from 11N90W to 1011 mb low pressure centered near 11N93W to 13N101W to 1011 mb low pressure centered near 12N104W to 07N115W to 08N121W. The intertropical convergence zone axis extends from 09N128W to 08N135W to 09N140W. Scattered moderate and isolated strong convection is seen within 60 nm either side of a line from 05N110W to 07N121W and also within 60 nm either side of a line from 09N128W to 07N138W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... The strong NW to N winds that have been blowing along the California Coast and westward to around 200 nm offshore have begun to subside. Latest satellite-derived wind data show these winds have subsided to fresh speeds. Satellite-derived sea height data indicate 8 to 10 ft seas extending southward from the waters west of California to west of Baja California Norte near 30N. This shows that the swell propagating S of 32N into the waters beyond 200 nm off Baja California Norte have begun to decay. This trend should continue and allow seas W of Baja California Norte to subside below 8 ft today. Elsewhere off the coast of the Baja California peninsula, seas range between 5 and 7 ft. Persistent ridging over the area will maintain gentle to moderate west to northwest winds through Saturday, although fresh to locally strong winds will occur mainly at night near Los Cabos Thursday through Saturday, and off Baja California Norte by Saturday as the pressure gradient tightens W of troughing over the Gulf of California. NW to N swell generated by strong winds off the California Coast could cause seas W of Baja California Norte to build to 8 ft as far S as 27N on Sunday night. Gentle to moderate southerly breezes will persist over the the northern Gulf of California through the week as a weak trough persists overhead. S of Acapulco and Manzanillo, a few showers and thunderstorms could form between the monsoon trough and 15N as the northern portion of a tropical wave migrates westward. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Convergence of light southwest flow into the monsoon trough and opposing drainage flow along the coastal terrain of Central America will generate scattered to numerous mainly overnight showers and isolated thunderstorms primarily north of 04N along the coastline. Gusty winds and rough seas will be possible in and near showers and thunderstorms. Light to gentle winds will prevail generally north of 10N accompanied by 4 to 6 ft seas. Moderate to fresh south to southwest winds are expected S of 10N with corresponding seas of 5 to 7 ft as cross-equatorial southwest swell augment combined seas. Seas will peak between 8 and 9 ft S of western Panama Thursday and Friday as S to SW flow becomes fresh, then winds and seas will slowly subside to between 4 and 6 ft by Monday. REMAINDER OF THE AREA... Recent observations indicated seas of 7 to 9 ft pushing S of 32N. This is N swell created earlier by fresh to strong winds blowing north of the area between high pressure centered W of California and low pressure centered near SE California. High pressure of 1023 mb is now centered near 33N133W and low pressure and troughing over California. Moderate to fresh N winds extend south along the California Coast to 30N between 118W and 128W. The high pressure will continue to weaken and gradually shift S through Thursday ahead of a late season frontal boundary moving eastward along the N portion of the discussion area. The high will generally maintain gentle to moderate trade-wind flow from 08N to 20N W of 120W. Outside of the area of N swell, seas N of 20N are generally 4 to 6 ft. Farther S, trade-wind affected seas have been diminishing during the past couple of days, but cross-equatorial S swell propagating into the region are adding an additional component to combined seas and maintaining seas above 7 ft S of 10N between 95W and 110W, and 7 to 9 ft seas near the equator and southward between 90W and 120W. The S swell will gradually decay and permit seas to subside below 8 ft by late week. High pressure will gradually rebuild on Thursday and Friday and bring moderate to fresh trade winds back to the area W of 125W and N of the ITCZ to 20N. The stronger high pressure will then remain in place through next weekend. $$ cam