000 AXPZ20 KNHC 092200 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2200 UTC Thu May 9 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 2100 UTC. ...SPECIAL FEATURES... Gulf of California Gale Warning: The pressure gradient between deepening low pressure over the Lower Colorado River Valley and an offshore high pressure ridge is enhancing gap winds over the northern Gulf of California. Recent scatterometer winds are showing SW-S fresh breeze in the northern Gulf, which will strengthen to gale force late tonight. Strong winds will persist over the northern Gulf Fri and Fri night north of 29.5N, then gradually diminish as the ridge west of Baja California breaks down. Otherwise, light to moderate winds will prevail over the central and southern Gulf through early next week. Please read the latest High Seas Forecast issued by the National Hurricane Center under AWIPS/WMO headers FZPN03 KNHC/HSFEP2 or at website https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for further details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A trough extends from 1011 mb low pres near 07N85W to 07N110W. The ITCZ continues from 07N110W to 06N135W, where it is broken by a trough along 137W, then continuing from 06N138W to beyond 05N140W. Widely scattered moderate convection is present within 180 nm of the trough east of 95W. Scattered moderate and isolated strong convection is located within 180 nm of the ITCZ west of 112W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A broad high pressure ridge extends into the region from high pressure centered well north of the area southeast to 30N140W to the Revillagigedo Islands. Moderate to fresh NW winds prevail over the open waters mainly north of 19N, as well as west and southwest of Cabo Corrientes. Elsewhere, generally light to moderate winds are occurring over the southern Mexico offshore waters. While agricultural fires persist over southern Mexico, low level winds are transporting the smoke northward toward the Gulf of Mexico. Therefore, no visibility impacts are expected over the Pacific waters at this time. Deepening low pressure over the Lower Colorado River Valley will support gap winds to gale force over the northern Gulf of California late tonight. Low pressure expected to develop off the coast of southern California on Fri will pull a weak surface trough across the northern waters. This will displace the ridge farther south into the weekend with fresh NW to N winds developing near the entrance to the Gulf of California and over the waters west of Cabo Corrientes. The surface ridge will become re-established along the northern boundary by Mon. Long-period SW swell will impact the open waters through early next week. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Agricultural fires continue over Central America, but the low level flow is transporting the smoke northward over the Gulf of Mexico. Therefore, no visibility impacts are expected over the Pacific waters at this time. Scattered showers and thunderstorms are active south of 10N in the vicinity of the seasonal low pressure trough. A significant S to SW Southern Hemisphere swell event will reach the Ecuador offshore waters tonight and spread northward across the waters off Central America through Sat night. Another round of SW swell will move across the region Sun and slowly diminish through Tue. No significant gap wind events are expected over the Gulf of Papagayo and Gulf of Panama through early next week. REMAINDER OF THE AREA... A broad high pressure ridge extends southeast across the northern waters from high pressure centered well north of the area southeast to 30N140W to the Revillagigedo Islands. Moderate to locally fresh trade winds prevail south of the ridge axis. The ridge will weaken and be displaced southward Fri into the weekend as low pressure develops off southern California and a trough moves across the northern waters. The surface ridge will become re- established along the northern boundary by Mon. Large, long period S to SW swell over the far southern waters will steadily propagate northward through this weekend. A recent altimeter pass over the southern waters roughly between 110W and 120W confirmed 10 ft seas about to reach the Equator. Seas will build to 12 ft south of the Equator between 100W and 110W by tonight with 8 ft seas spreading as far north as 09N by Fri night. By Sun, the southerly swell will cover the forecast waters south of 20N and east of 120W with combined seas of 8 ft or greater south of 10N. Seas will subside beginning Mon as the long period swell gradually decays in this region. $$ Landsea