000 AXPZ20 KNHC 041021 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Thu Aug 4 2016 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. ...SPECIAL FEATURES... Tropical Storm Ivette is centered near 14.7N 124.7W at 0900 UTC, or about 975 nm WSW of the southern tip of Baja California, moving W or 275 degrees at 13 kt. Estimated minimum central pressure remains 1004 mb. Maximum sustained winds are 40 kt with gusts to 50 kt. Dry middle level air and modest upper wind shear appear to be impacting Ivette this morning and limiting convection associated with the system. Scattered moderate to strong convection is occurring within 45 nm across the northeast and 120 nm across the southwest semicircles. The has temporarily limited further intensification. However, as Ivette moves west- northwest today and Friday, gradual strengthening is expected to occur, with Ivette forecast to reach hurricane strength within 48 hours. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCMEP5/WTPZ25 KNHC for more details. Post Tropical Storm Howard is centered near 21.5N137W at 0900 UTC. Estimated minimum central pressure has increased to 1010 mb. Maximum sustained winds are 30 kt with gusts to 40 kt, and are occurring within 90 nm across the north semicircle. Howard has moved across slightly warmer waters in the past few hours, and the upper level wind shear has abated slightly. This has allowed for some deep convection to return, with scattered moderate convection noted within 120 nm across the north semicircle. Howard will move west during the next 24 hours and weaken very slowly, with associated winds and seas moving west of 140W by 36 hours. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCMEP4/WTPZ24 KNHC for more details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A discontinuous monsoon trough extends from 13.5N90W to 12.5N97W to 08N113W to 10N117W. The ITCZ extends from 10.5N128W to 09N140W. Scattered moderate to strong convection is noted from 03N to 06.5N east of 80W. Scattered to numerous moderate to strong convection is occurring north of 10N between 87W and 97W. Widely scattered moderate isolated strong convection is noted within 180 nm north of trough between 107W and 115W. Widely scattered moderate to strong convection is noted within 120 nm north and 90 nm south of the ITCZ between 128W and 139W. ...DISCUSSION... N of 15N E of 120W: Weak surface troughing will generally prevail along the Baja California peninsula through the weekend. Light to moderate S winds will prevail across the north and central Gulf of California for the next few days. A weak surface ridge extends into the area from the NW to about 15N110W. This ridge will support gentle to locally moderate NW winds across the open Pacific waters offshore of Baja California, with seas 4-6 ft range in mixed N and SW southern hemisphere swell increasing to 5-7 ft in fresh northerly swell on Saturday. Across the Gulf of Tehuantepec, northerly winds have increased to 20-30 kt overnight, with seas building to 6-9 ft. Winds and seas are expected to subside modestly this afternoon through Saturday. However, a large cluster of heavy showers and thunderstorms occurring well ahead of Hurricane Earl, now across Belize, has developed overnight from about 10N to coastal portions of Mexico, Guatemala, el Salvador and northwest Nicaragua. This weather is expected to shift slowly west and northwest through the weekend, and could produce torrential rainfall across portions of the area from the Tehuantepec region to Jalisco Mexico by Sunday evening. Please refer to the latest bulletins and advisories from your local weather agencies. S of 15N E of 120W: East of 100W, light to moderate monsoonal winds are expected through Saturday as Earl moves across central America and weakens across southeast Mexico. Widespread showers and scattered thunderstorms are occurring over Central America well removed from Earl. This very active weather is expected to continue across the tropical eastern Pacific and central America through Saturday. Torrential rainfall and flash flooding will be possible across the mountainous interior of the area during this time. See the latest bulletins and advisories from your local weather agencies. Long-period cross-equatorial SW swell will produce 4-7 ft seas across the region the next few days. W of 120W: TS Ivette has crossed to the W of 120W and Post Tropical Cyclone Howard will continue weakening and exit the forecast waters by Friday morning. See the special features section for details. Ridging extending into the region from NW of the area is maintaining moderate to occasionally fresh NE to E winds. Fresh to strong NE winds offshore of California will generate fresh NNE swell that will move into the northern waters. Seas to 8 ft will propagate southward but remain N of 30N through Sunday. $$ Stripling