FXUS66 KLOX 310146 AFDLOX Area Forecast Discussion...UPDATED National Weather Service Los Angeles/Oxnard CA 646 PM PDT Fri Aug 30 2024 .SYNOPSIS...30/239 AM. Slight warming is expected today through Sunday as onshore flow weakens and high pressure covers most of the western third of the country. By Sunday temperatures in most areas will be at or slightly above normal. Night and morning low clouds will continue across the coastal areas and some valleys into the weekend. A warming trend next week will bring temperatures to 8 to 15 degrees above normal by the middle of next week. && .SHORT TERM (TDY-MON)...30/1251 PM. Overall, 12Z models in good synoptic agreement through the short term period. At upper levels, high pressure will remain centered over the desert Southwest with minor day-to-day changes in H5 heights over Southwestern CA. Near the surface, onshore gradients will weaken through the period with an increase in northerly offshore gradients. Forecast-wise, no significant issues are anticipated through Monday. Overall for most areas, skies will remain mostly clear through the period. However, marine layer stratus/fog will continue to impact the coastal plain and some lower coastal valleys. Through the weekend, the depth of the marine inversion will remain persistent, if not become a bit more shallow. With the previously mentioned surface pressure gradients, the areal coverage of stratus/fog will diminish from night to night. As for wind, no major concerns are expected through Sunday afternoon with just some locally breezy southwesterly winds across interior sections. For Sunday night, the northerly offshore gradients do increase which will result in a chance of advisory level Sundowner winds across the western half of the Santa Ynez Range. As for temperatures, most areas can expect a gradual warming trend through Monday with best warming across interior sections. By Sunday and Monday, some coastal valley areas will have high temperatures hovering near 100 degrees. .LONG TERM (TUE-FRI)...30/1251 PM. Overall, 12Z models still exhibiting decent synoptic agreement through the extended period. Main feature of concern will be upper level high that strengthens over the area through the period. At this time, the deterministic ECMWF is a bit stronger with the high than the GFS. Looking at clusters and ensembles, the best bet is for something in between the ECMWF and GFS. To that end, it looks like a pretty significant stretch of heat through the period with Thursday likely the hottest day. Looking at the NBM numbers, there's a high likelihood of temperatures in the 100-110 degree range for areas away from the coast Wednesday through Friday with temperatures in the mid 80s to mid 90s range for many coastal areas. Latest Heat Risk forecasts indicate many areas in the Moderate to Major levels. So, as we enter next week, there is a decent chance of various heat-related products being issued. One thing to be watched for the Wednesday-Friday time frame will be the forecast surface pressure gradients. The deterministic ECMWF still is indicating some decent northerly offshore gradients and weak northeast offshore gradients. If these materialize, coastal temperatures could be warmer than currently forecast and there could be a bit more offshore wind than currently forecast. && .AVIATION...31/0145Z. At 00Z at KLAX, the marine layer was 1100 feet deep. The top of the inversion was 3500 feet with a temperature of 28 Celsius. High confidence in TAFs for KPMD and KWJF. Moderate to low confidence in all other TAFs, with lower confidence in cig arrival/disappation timing. Arrival of cigs could be off by +/- 3 hours. There is a 30% chance of IFR cigs at KBUR, KVNY, and KPRB 09Z-16Z. Dissipation of cigs could be as late as 23Z for coastal sites. KLAX...Low confidence in TAF through 06Z Friday, then moderate confidence. BKN008-012 cigs could form and then scatter through 06Z, before reforming for the night. High confidence in any east wind component staying under 06 knots. KBUR...High confidence in VFR conditions through at least 08Z and after 16Z. There is a 30% chance of BKN006-008 cigs between 09Z-16Z, with a 50% chance of 3-5SM HZ. && .MARINE...30/1228 PM. For the offshore waters from the Central Coast to San Nicolas Island (Outer Waters), moderate confidence in low-end Small Craft Advisory (SCA) conditions continuing through most of tonight. The lowest confidence is for the waters north of Point Sal, where winds could stay below. Confidence increases for SCA conditions Saturday afternoon which will likely last through most of next week. For the nearshore waters, SCA conditions unlikely through at least the holiday weekend, except for localized gusts to 25 knot each afternoon mainly a few miles offshore. Dense fog is likely to be an issue each morning, especially deeper into next week. For the Santa Barbara Channel, SCA winds will likely form over the western portion each afternoon and evening through much of next week, but moderate confidence that such winds will not be widespread enough to warrant an SCA through at least the holiday weekend. In the inner waters off the Los Angeles and Orange County coasts, high confidence that conditions will stay under SCA through at least the holiday weekend. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...Small Craft Advisory in effect until 3 AM PDT Saturday for zones 670-673-676. (See LAXMWWLOX). && $$ PUBLIC...Thompson AVIATION...Lund MARINE...Kittell SYNOPSIS...MW weather.gov/losangeles Experimental Graphical Hazardous Weather Outlook at: https://www.weather.gov/erh/ghwo?wfo=lox