441 AXPZ20 KNHC 160353 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Thu Aug 16 2018 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 0230 UTC. ...SPECIAL FEATURE... Tropical Storm Lane is centered near 10.4N 125.6W at 0300 UTC, moving W at 11 kt. Estimated minimum central pressure is 1003 mb. Maximum sustained wind speed is 45 kt with gusts to 55 kt and extend out to 30 nm across the SE quadrant. Peak seas are about 14 ft just NE of the center. Scattered to numerous moderate to strong convection is occurring within 120 nm across the SE and 30 nm across the NW semicircles, while scattered moderate isolated strong convection is elsewhere within 180 nm across the NW and 240 nm across the SE semicircles. Lane is expected to continue moving westward through Thu morning and gradually intensify, reaching hurricane strength Thu evening, then begin to veer more WNW and intensify further to major hurricane status around Sat. The small size of Lane is anticipated to retain gale force winds of less than 100 nm radius and will limit the extent of 12 ft seas during the next few days. See latest NHC forecast/ advisory under AWIPS/WMO headers MIATCMEP4/WTPZ24 KNHC for more details. The Fuego Volcano in Guatemala near 14.3N90.5W emitted an ash cloud or plume this afternoon around 1916 UTC, and spread potential ash westward in the prevailing easterly low level winds. Ash may be reaching the surface as the easterly winds transport this ash cloud westward over the Pacific waters to the west and across the Gulf of Tehuantepec tonight, generally from 14N to 16N between 91W and 95W. Mariners operating in this area are advised to exercise caution. If you encounter volcanic ash or floating volcanic debris, please report your observation to the National Weather Service at 305-229-4425. ...TROPICAL WAVES... A tropical wave extends from the northwestern Caribbean, across Central America, and into the Pacific down to about 08N near 83W. Scattered moderate to strong convection is occurring ahead of the wave along the monsoon trough from 04.5N to 08.5N between 83W and 94W, while scattered moderate convection is seen behind the wave across interior Costa Rica and Panama and across the SW Caribbean. A tropical wave along 102W-103W extends from 05N to 19N moving W 10-15 kt. Scattered moderate to strong convection is observed about the wave from 07.5N to 14.5N between 97W and 111W. A 1010 mb surface low is lingering along the monsoon trough ahead of the wave near 09.5N109.5W. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 09N74W TO 08N92W to low pres near 09.5N109.5W TO 11N114W. The ITCZ extends from 13.5N137W TO beyond 11N140W. Scattered moderate to strong convection is seen in satellite imagery from 04.5N to 08.5N between 83W and 94W, and from 07.5N to 14.5N between 97W and 111W. Scattered moderate to strong convection is observed within 90 nm SE of the ITCZ west of 137W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Weak surface ridging extends from the NE Pacific Se into the area from around 30N135W to near las Islas Revillagigedo. A weak trough associated with the remnants of tropical cyclone John area across the coastal waters near Punta Eugenio, and aiding in producing gentle N to NW winds across the near shore waters of Baja California, and moderate NW winds further offshore. NW winds should remain moderate or weaker for the next several days and this weak ridge prevails. No significant gap wind events are expected in the Gulf of Tehuantepec, although nocturnal northerly drainage flow to around 20 kt is expected there each night. Long-period S to SW swell originating south of the equator is impacting the Mexico offshore zones from Cabo Corrientes southeastward, producing seas of 7 to 10 ft. This swell is generating very large and dangerous surf conditions along the coastlines and outer reefs with localized breaking waves of 15 to 20 ft expected through Thu morning. These swell will gradually be diminishing during the next two to three days. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... The monsoon trough should remain near 10N during the next few days. Easterly winds north of the trough will be moderate or weaker, while southwesterly winds south of the trough will also be moderate breeze or weaker. Long-period SW swell originating south of the equator is also impacting the Central America, Colombia, and Ecuador offshore zones, producing seas of 6 to 9 ft. Large breaking waves are also occurring across these coastlines and outer reefs with localized breaking waves of 10-15 ft expected through Thu morning. These swell will gradually be diminishing during the next two to three days. REMAINDER OF THE AREA... See discussion above for Tropical Storm Lane. A weak 1012 mb low pressure center is located near 18N138.5W and moving westward near 15 kt. Scattered moderate isolated strong convection is observed within 150 nm across the NW semicircle and within 90 nm of the center in the northern semicircle. across the SE quadrant. Fresh to strong easterly winds are occurring across the northern periphery of the low center, due to the pressure gradient imposed by the ridge centered north of the area. Seas within this area of winds are 7-9 ft. Building high pressure north of the area will maintain this area of fresh easterly winds today, even as the low pressure opens into a trough over the next couple of days, and moves to the west of 140W late Thu. Long-period cross-equatorial S southerly swell, in the form of 7 to 9 ft seas, will propagate N across the tropical waters S of 20N E of 120W tonight through Thu, and then subside to less than 8 ft on Thu night. $$ Stripling