000 AXPZ20 KNHC 312202 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1904 UTC Mon Jul 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 1800 UTC surface analysis and satellite imagery through 2100 UTC. ...SPECIAL FEATURES... Tropical Storm Irwin is centered near 22.7N 127.7W at 31/2100 UTC or about 980 nm W of the southern tip of Baja California moving NNW at 11 kt. Estimated minimum central pressure is 1006 mb. Maximum sustained wind speed is 40 kt with gusts to 50 kt. Scattered moderate convection is present within 60 nm in the NE semicircle. Irwin is expected to maintain a NNW course during the next 24 hours and move over cooler waters. This will cause Irwin to lose convection and continue weakening. Irwin is expected to become a post-tropical cyclone within 24 hours. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCMEP5/WTPZ25 for more details. ...TROPICAL WAVES... A tropical wave extends from 06N91W to low pres 1010 mb near 09N91W to 15N91W moving W at 15 to 20 kt. Scattered moderate and isolated strong convection is seen from 05N to 13N between 86W and 93W. Low pressure along the wave will help enhance winds and seas for the waters adjacent to Central America. A tropical wave extends from 09N96W to 18N96W moving W at 10 to 15 kt. Scattered moderate and isolated strong convection is found from 05N to 08N between 93W and 100W and from 13N to 15N between 96W and 100W. A tropical wave extends from 09N110W to 19N109W moving W around 5 kt. A small area of scattered moderate convection is associated with this wave from 10N to 13N between 108W and 112W. This wave may remain ill-defined during the next few days. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 10N84W to low pres 1010 mb near 09N91W to 10N115W. The intertropical convergence zone axis continues from 10N115W to 07N129W, then continues as a northern extension from 13N128W to beyond 10N140W. Other than convection associated with tropical waves, there is no significant convection. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A narrow ridge extending SSE across the area between the remnant circulation of Hilary and Tropical Storm Irwin and the Baja Peninsula has generated fresh winds over the forecast waters. These stronger winds caused seas to build to between 7 and 8 ft off of Baja California Sur. The ridge will weaken tonight through Tuesday and allow winds and seas to diminish. Generally light to gentle winds will persist elsewhere over the Gulf of California and the offshore Mexican waters south of 20N through mid week. Otherwise, lingering long period S swell from the Southern Hemisphere will maintain seas of 5 to 7 ft. Slowly developing low pressure associated with westward moving tropical waves is expected to bring fresh to strong winds and seas building above 8 ft to the waters between the Gulf of Tehuantepec and Cabo Corrientes Wed through Fri. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Moderate to fresh SW monsoonal flow S of 08N and cross- equatorial southerly swell are combining to produce combined seas of 7 to 9 ft across the waters. Seas will begin to slowly subside Tuesday through Wednesday as the S swell decay. A pair of tropical waves extending S from SE Mexico and from Guatemala are producing active convection along the coast of Central America from Costa Rica to Guatemala. These waves are expected to merge by mid week as then continue moving W. Fresh to strong E to SE winds will develop along and behind the easternmost wave across the waters of Guatemala and El Salvador on Tuesday as low pressure along the wave continues to develop. building seas to around 8 ft. REMAINDER OF THE AREA... Low pressure, the remnant of Hilary, is centered near 27N131W at 1011 mb. Fresh to strong winds and seas of 8 to 11 ft are occurring within 120 nm in the N semicircle of the low, with a surrounding area of 8 to 10 ft seas in mixed swell. The low will dissipate during the next couple of days as it continues to the NW. High pressure centered off the NW Coast of the United States extends a narrow ridge axis through 32N124W parallel to the coast of Baja California. The pressure gradient between the high pressure system and the active zone of tropical cyclones will maintain moderate N to NE winds N of 20N and W of 130W tonight. Long period cross equatorial SSW swell continues arriving across the waters S of 08N and E of 110W. The swell will produce seas of 7 to 10 ft, which will persist until the swell decay around mid week. A weak pressure pattern will persist between the remnants of both Hilary and Irwin, and the equatorial trough to the S. This will result in a broadening area of gentle to moderate winds between 10N and 20N, W of 120W through the end of the week. $$ CAM