681 FXUS66 KLOX 250351 AFDLOX Area Forecast Discussion National Weather Service Los Angeles/Oxnard CA 851 PM PDT Thu Jul 24 2025 .SYNOPSIS...24/421 PM. Night through morning low clouds and fog will continue to be a staple of the forecast for most coast and some valley locations through Sunday. Persistent onshore flow will remain in place through the weekend over the California coast and keep an onshore flow regime across the area. Temperatures will continue to be on the cool side of seasonal normals into early next week, then a warming trend should start to develop as onshore flow weakens. && .SHORT TERM (THU-SUN)...24/850 PM. ***UPDATE*** The upper level low up north continues to support a deep marine layer with clouds reaching far into interior San Luis Obispo County, while at the same time, high pressure starts building in from the south. This morning, satellite imagery showed significantly less coverage of stratus for Ventura and LA Counties. We should see a similar pattern overnight tonight, but heights are trending lower south of Point Conception which means we could see a bit more stratus tonight than last night. Breezy sundowner winds have developed over western portions of the Santa Ynez range, but are expected to stay below advisory levels tonight. Temperatures look similar with minimal changes and the current forecast looks on track. ***From Previous Discussion*** A few clouds linger along the beaches this afternoon, but mostly clear skies prevail across the land mass today. Low clouds and fog will return again tonight across most coastal and valley areas as a persistent and deep marine layer depth remains in place. Strong onshore flow is likely to persist through the weekend as a weak upper-level trough of low pressure will linger over the California coast into Sunday. Low clouds and fog are expected to become well-entrenched tonight and into Friday morning due to strong onshore flow. An eddy circulation in place across the southern California bight this morning will likely reform and strengthen overnight as a low-level northwest flow parallel to the southern California coastline creates a conducive environment for eddy generation. The marine layer depth near 1300 feet deep at KLAX currently should deepen overnight to between 1600 and 2000 feet deep. As the trough axis approaches the coast on Saturday, the marine layer depth should deepen additionally to between 2000 and 3000 feet deep. Patchy night through morning drizzle cannot be ruled over as some weak instability is moving over the region tonight and into Friday morning, and again Friday night and into Saturday morning. With strong onshore flow and a persistent marine layer depth in place, the air mass will continue to remain on the cooler side of normal. A cooling trend should continue into Saturday. A low-level northwest flow pattern in place will enhance the diurnal downslope wind regimes over the next couple of days. Marginally strong Sundowner winds will develop each night, potentially nearing advisory levels this evening across southwestern Santa Barbara County. NAM-WRF surface pressure gradients suggest KSBA-KSMX values to be on the weak side of advisory criteria, while NAM BUFR time height sections indicate wind maximums in the core of the Sundowner winds to be just shy of advisory levels. Any issuance of a wind advisory will be tabled for now. Local gusts to 45 mph may still occur this evening near Gaviota, but the winds look to be shy of advisory levels. Between Saturday and Sunday, the trough axis will move ashore and the marine layer depth should start to shrink. The most notable thinning of the marine layer depth is expected along the Central Coast. Onshore flow should still remain intact and keep temperatures below normal, but a warming trend will start to develop, especially away from the coast. .LONG TERM (MON-THU)...24/210 PM. A warming trend will continue into much of next week as 500 mb heights rise through the period. Cluster analysis hold on to an upper-level trough to the northwest of the region, which should allow for onshore flow to persist. Onshore pressure will be weaker, but persistent night through morning low clouds and fog are likely to persist across most coastal and some lower valley areas. EPS ensemble members favor warming over the region, especially away from the coast and into the interior valleys and desert. A few degrees of warming will likely take shape each day. Closer to the coast, onshore flow will likely keep the warming trend more moderated. A low-level northwest flow pattern is likely to persist with a cooler air mass to the northwest and a warmer air mass over the Desert Southwest region. The possibility of gusty Sundowner winds will remain in the forecast each evening as a result. && .AVIATION...25/0246Z. At 2328Z at KLAX, the marine layer was around 1000 ft deep. The top of the inversion was around 2900 feet with a temperature of 20 C. High confidence in VFR TAFs for KWJF and KPMD. Moderate to high confidence in TAFs for KPRB, KSBP, KSMX, and KSBA. Lower confidence in remaining coastal sites. Arrival of cigs may be off by +/- 2 hours. There is a chance for IFR cigs at KPRB, KSBP, KCMA, KOXR, and KSMX after cigs arrive. Moderate confidence in TAFs for KBUR and KVNY. There is a 10-20% chance for IFR/MVFR cigs between 10Z and 16Z. KLAX...Moderate confidence in TAF. Arrival of cigs tonight may be as early as 08Z or as late as 13Z. Minimum cig height may be off +/- 200 ft. Any east component wind between 08Z and 17Z should remain below 6 kts. KBUR...Moderate confidence in TAF. There is a 10-20% chance of brief cigs around 11Z to 16Z. && .MARINE...24/841 PM. NW Small Craft Advisory (SCA) winds will impact the outer waters south of Point Conception through the period, especially in the afternoon and evening hours. Winds will increase to SCA levels for the northern outer waters Sunday afternoon and continue through the remainder of the period. The inner waters along the central coast will see local SCA level gusts in the afternoon and evening through Saturday, then SCA winds will become more widespread Sunday through the period (50% chance for SCA issuance each day). For the Santa Barbara Channel, moderate to high confidence in SCA level winds across most of the Channel through late night, and high confidence in SCA winds returning Friday afternoon and night, with a 40-50% chance for SCA level winds reaching nearshore from Ventura Harbor south to Point Mugu. Then SCA level winds will impact the western half of the Channel each afternoon/evening through the period, with lower chances of winds reaching the eastern portion. For the inner waters off the coast of Los Angeles and Orange Counties, SCA level WNW wind gusts affected areas around Point Dume, across the Santa Monica Bay (including nearshore), the San Pedro Channel, and south and west of Catalina Island. Another round of weaker SCA level winds are possible Friday afternoon and evening for a similar area (40% chance for an SCA issuance). Thereafter, sub- advisory conditions are likely into next week. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...Small Craft Advisory in effect until 3 AM PDT Friday for zone 650. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PDT Saturday for zones 673-676. (See LAXMWWLOX). && $$ PUBLIC...Hall AVIATION...Phillips MARINE...Lewis/Ciliberti SYNOPSIS...Hall/Ciliberti weather.gov/losangeles Experimental Graphical Hazardous Weather Outlook at: https://www.weather.gov/erh/ghwo?wfo=lox