000 AXPZ20 KNHC 090220 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Tue Jul 09 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 0000 UTC surface analysis and satellite imagery through 0130 UTC. ...TROPICAL WAVES... A tropical wave along 91W and north of 04N to the Yucatan Peninsula is moving westward 15-20 kt. Very active weather in the form of scattered to numerous strong convection is occurring from 04N to 13N between 86W and 98W. A 1010 mb surface low is suggested by satellite imagery near 08.5N91W. Computer models suggest that this low will move WNW over the next few days and attempt to become better organized, while maintaining active convection. However, as this low and tropical wave crosses 105W Thu night through Fri, atmospheric conditions are not expected to be favorable for improved organization, and the low will likely open up into a trough. A tropical wave along 113W from 02N to 12N is moving westward around 10 kt. Scattered moderate to strong convection is noted from 04N to 09N between 106W and 111W. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 09.5N74W TO 10N85W to low pres near 08.5N91W 1010 mb to 06N99W TO 06N117W. The ITCZ extends from 12N125W TO 09N135W to beyond 09N140W. Scattered moderate isolated strong convection is from from 10N TO 14N between 99W AND 105W, and from 06.5N TO 09.5N west OF 135W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A broad high pressure ridge persists across the Baja California offshore waters. Afternoon scatterometer data showed gentle NW to N winds across the Baja waters north of Cabo San Lazaro, while moderate NW winds prevail surrounding the coast at Cabo San Lucas. Little change in the overall pattern is expected through Wed as daytime heating will support locally fresh winds near the coast during the late afternoon and early evening hours. The ridge will strengthen slightly across the area Thu through Fri as the remnants of Cosme weaken and move well westward of 120W. This will produce fresh NW winds across much of the offshore waters during this time, with afternoon heating leading to locally strong late afternoon and evening winds. Swell from former Tropical Cyclone Cosme is producing waveheights of 6-7 ft over the outer waters SW of Cabo San Lazaro with 5-6 ft waveheights near the entrance to the Gulf of California. These seas will subside slightly through Tue. Gulf of California: Fresh to strong SW gap over the northern Gulf of California have gradually diminished to moderate winds this evening, with seas of 2-3 ft. These SW gap winds will freshen again tonight and build seas to 4-5 ft. Over the southern portions, gentle to moderate west to northwest winds will become light and variable by Wed, then shift to the southeast Thu through Fri as a low pressure trough strengthens near Baja California. Gulf of Tehuantepec: Fresh northerly gap winds across the Gulf of Tehuantepec this afternoon will diminish further tonight through Tue. Varying gentle winds will prevail through the rest of the week with seas less than 8 ft. Very active convection associated with a tropical wave along 90W will spread into the offshore area tonight through Tue. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Very active weather will continue across the offshore waters west of 86W tonight through Tue, and shift gradually westward with the tropical wave. This active weather is expected to shift south of the Gulf of Tehuantepec by Tue night and exit the area. Otherwise, a north-south pressure gradient across Central America will support pulsing fresh gap winds between the Gulf of Fonseca and the Gulf of Papagayo through Wed. Waveheights downstream of the gulfs will reach 5-7 ft each day. Long period south to southwest swell currently propagating through the waters will diminish by Tue. Another round of southerly swell will begin to propagate through the southern waters beginning late Thu night with waveheights building to 10 ft between Ecuador and the Galapagos Islands on Fri, and 8 ft seas developing over the Central American offshore waters. REMAINDER OF THE AREA... The Post-Tropical remnant low of former Tropical Storm Cosme was centered near 21N120.5W this evening moving to the north- northwest at 5 kt. Winds are assumed to still remain at 20-25 kt within 150 nm of the center in the northwest semicircle, where seas are 8-9 ft. The remnant low is devoid of any deep convection as it is tracking over cool waters and is also surrounded by dry and stable air. The remnant low will continue to move in a general northwest direction through Wed, while gradually weakening into an open trough. See last issued NHC forecast/advisory issued at 15 UTC under AWIPS/WMO headers MIATCMEP3/WTPZ23 KNHC for more details. Morning altimeter data showed an area of 8 to near 10 ft waveheights over the waters from 11N to 23N between 114W and 125W, and surrounding the remnants of Cosme. Seas will subside below 8 ft on Tue as this swell decays. An area of 8 ft seas persists over the waters roughly W of a line from 17N140W TO 11N137W TO 10N140W, where there is a mix of SE and SW swell merging with NE waves from the tradewinds. These seas will subside through Tue as the swell decays and trade winds weaken slightly. Elsewhere, the pressure gradient across much of the high seas domain remains weak. The persistent broad ridge centered just north of the area will sink slightly SE and produce moderate to locally fresh winds across the tradewind belt Wed through Thu. $$ Stripling