000 AXPZ20 KNHC 202118 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2000 UTC Thu Jun 20 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 2000 UTC. ...TROPICAL WAVES... A western Caribbean Sea tropical wave has its axis along 83W and extending southward to near 06N. Increasing deep convection is occurring near where the wave axis crosses the monsoon trough as described below. A tropical wave with axis along 93W from 04N to 15N moving westward at 10-15 kt. Scattered to numerous moderate to strong convection is seen from 10N to 13N between 91W and 94W. A tropical wave with axis along 105W from 04N to 14N is moving westward near 15 kt. Only scattered showers and isolated thunderstorms are noted along this wave from 09N to 12N. A tropical wave with axis along 125W from 05N to 16N is moving westward at an estimated speed of 15-20 kt. Convection has diminished today somewhat, but scattered showers and isolated thunderstorms remain mainly along and east of this wave where it crosses the ITCZ. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from a northern Colombia southwestward to 08N78W to 10N88W to 09N98W to 08N105W to 12N118W to 09N126W, where scatterometer data continues to indicate that it transitions to the ITCZ around 09N126W, which continues through 08N140W. Numerous to strong convection is within 180 nm south of the trough between 78W and 92W. Scattered moderate convection is within 60 nm of the trough between 96W and 103W, and also within 60 nm south of the ITCZ between 126W and 136W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Midday scatterometer data continued to show gentle to moderate northwest wind across offshore waters as weak high pressure dominates E of 130W. Various altimeter satellite passes from between 16 UTC and 18 UTC showed seas at 4-6 ft. Low pressure over the southwestern U.S. will deepen some today, and a surface trough will continue to extend from this low over the Gulf of California. This will cause winds to increase over the northern Gulf of California, producing strong to near gale force south to west gap winds beginning early this evening. These winds will diminish to mainly fresh speeds by early Sat afternoon before increasing again to strong speeds late on Fri night and into early Sat. Farther south, the northern part of a weak tropical wave will brush the extreme southern part of the Mexican offshore waters through early Fri. Scattered to numerous showers and thunderstorms, with possibly strong gusty winds, will impact these waters as the wave passes across there. A low pressure may form at the start of next week 180 nm or more offshore the coast of southern Mexico. These may bring additional showers and thunderstorms, as well as increased winds and seas. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Late morning scatterometer data recorded gentle and moderate breezes across the waters, and these winds will likely continue through the weekend. Tight pressure gradient between high pressure north of the Caribbean Sea and low pressure along the monsoon trough will continue to support overnight pulses of gap wind in the Papagayo region, with speeds of 20 to 25 kt expected. Swell from the southern hemisphere will continue propagating northeastward offshore Ecuador. This swell, according to 15 UTC altimeter satellite pass, is producing waves of around 8 feet, and these seas should generally persist through the weekend. REMAINDER OF THE AREA... A 1032 mb high remains quasi-stationary well north of the area near 42N139W, with a ridge extending southwestward through the Revillagigedo islands. To the south of the high pressure, northeast to east trade winds of 15 to 20 kt prevail, as supported by 19 UTC scatterometer data. Little change in the position of the high or the speed of the trade winds is expected through the weekend. North of 25N, 3 passes of altimeter satellite revealed seas of 8 to 10 ft, due to northerly swell being generated by persistent gale force winds off the coast of California. The focus of this swell will move east and gradually shrink in size this weekend. Farther south, long-period cross-equatorial swell is causing seas of 8-9 feet south of about 07N. This swell will decay some Friday, before new swell arrives this weekend, again increasing seas south of 08N to possibly 8-10 feet. $$ KONARIK