355 FXUS66 KLOX 201629 AFDLOX Area Forecast Discussion National Weather Service Los Angeles/Oxnard CA 929 AM PDT Mon Oct 20 2025 .SYNOPSIS...19/1154 PM. Dry and uneventful weather will occur today and Tuesday with high temperatures a little below normal across the coasts and valleys and a little above normal across the interior. A deep marine layer will bring clouds and some drizzle to all of the coasts and valleys on Wednesday. Max temperatures on Wednesday will fall dramatically with highs only in the mid 60s to lower 70s across all of the coasts and vlys. Dry and warmer conditions are slated for the end of the week. && .SHORT TERM (TDY-WED)...20/928 AM. ***UPDATE*** With improving conditions we have let the Dense Fog Advisory over the Central Coast expire at 9 am. Patchy dense fog may continue through 10 or 11 am. The focus for today will be looking into the Wednesday storm which features mainly low chances for showers or drizzle, although thunderstorms cannot be ruled out especially across the high terrain. Other weather highlights include a weakening cold front this weekend with any potential light rain focused across San Luis Obispo and northern Santa Barbara Counties. Gusty west to northwest winds may be a bigger impact with this system. ***From Previous Discussion*** Pretty boring weather day today. Srn CA is under a weak ridge with 587 dam hgts overhead. To the SW a large dry upper low is spinning and not moving much. Near neutral flow at the sfc has not allow much in the way of marine layer formation or penetration. The high hgts have smooshed the marine layer low enough to create pockets of dense fog across the Central Coast and the Santa Ynez Vly where a dense fog advisory is in effect until 900 am. Otherwise it will be sunny day with cooler conditions at the coast due to weaker offshore. Not much change on Tuesday the upper low will nudge a little closer as it begins its trek to the NE. There will be a little more onshore flow and this should result in a little more marine layer stratus across the coasts. The increased onshore flow will bring 2 to 4 degrees of cooling to the csts/vlys while the interior sees little change in temperatures. On Tuesday night and Wednesday the upper low to the SW will move to the NW and will move over the area. The lowering hgts and lift from the lows approach will quickly deepen the marine layer. It will likely deepen to around 5000 ft. This will bring low clouds to all of the csts and vlys as well as the coastal slopes and some mtn passes. The rapid deepening will also likely bring some drizzle or even light rain to the csts/vlys esp areas near the foothills. There is a non zero chance of some mtn convection in the late morning or afternoon but the exact chc depends on the track and timing of the low's passage. Will keep convection out of the fcst for now and will wait for the hi rez mdl window to open up. One thing is for certain - the falling hgts and clouds will bring 2 to 4 degrees of cooling to the csts; 5 to 10 degrees for the vlys; and 8 to 12 degrees for the mtns and interior. Max temps will end up 5 to 10 degrees blo normal with only upper 60s to mid 70s for highs across the csts/vlys. .LONG TERM (THU-SUN)...20/1228 AM. Two days of dry low impact weather on Thursday and Friday. A weak ridge will nose into Srn CA from the west and hgts will bump up to about 584 dam. At the sfc there will be weak onshore flow to the east and weak offshore flow from the north. Night through morning low clouds will likely affect most of the coasts, but only the lower vlys. The rising hgts and increased sunshine will lead to 3 to 6 locally 8 degrees of warming on Thursday and 2 to 4 additionaldegrees on Friday. Friday's max temps will come in within a few degrees of normal. Less confidence in the weekend forecast as a very large trof will cover the entire west coast. A weak front embedded in this system will move into and then pass through the state Sat night and Sunday. The most likely scenario favored by most of the ensembles and the AI infused EC is for cloudy and dry conditions. But 20 to 30 percent of the ensembles do bring light rain to SLO and SBA counties. Rainfall amounts, if any, will be under a quarter inch with inconsequential rainfall rates. Max temps will cool 2 to 4 degrees each day with the increased clouds and lowering hgts. Max temps by Sunday will mostly see highs in the 70s across the csts and the vlys. These max temps will be 4 to 8 degrees blo normal. Looking beyond the 7 day forecast it does appear that a decent wind event is shaping up for Tue and Wed. On Tuesday a north wind is possible, but on Tuesday it is looking more and more likely that the first moderate Santa Ana wind event will occur. Nothing is for sure with a forecast 10 days out, but it will be monitored. && .AVIATION...20/1122Z. At 0744Z, the marine layer depth was around 900 feet deep at KLAX. The top of the marine inversion was near 1700 feet with a temperature around 23 degrees Celsius. High confidence in TAFs for KPRB, KBUR, KVNY, KPMD, and KWJF. Moderate confidence in remaining TAFs. Timing of transition to VFR may be off +/- 90 minutes. Arrival of low clouds tonight may be off +/- 2 hours. 20-40% chance for brief LIFR-IFR conds at KOXR, KSMO, and KLAX through 18Z, highest at LA County Coastal sites. 20% chance for no cigs KLGB this morning. Chance for VLIFR to IFR conds at KSBA (10%) KOXR (25%), KCMA (15%), KSMO (30%), KLAX (40%), and KLGB (40%) from 06Z-18Z. KLAX...Moderate confidence in TAF. 20% chance for vsbys of 2SM-5SM and OVC004-010 cigs through 18Z this morning. 40% chance of 1-2SM vsbys and cigs OVC003-006 between 06Z and 18Z Tues. No significant east wind component expected. KBUR...High confidence in TAF. && .MARINE...20/831 AM. Patchy dense fog is currently observed across portions of the coastal waters and is expected to last into late this morning. Please refer to the Marine Weather Statement for more information. A moderate to long period northwest swell will continue to bring 7-11 foot seas to the outer waters and nearshore waters along the Central Coast through the week. A Small Craft Advisory (SCA) has been issued for this afternoon through late tonight as seas are expected to reach 10-11 feet for the outer waters adjacent to the Central Coast more than 20 NM away from the coast. Period of SCA level seas will continue off and on through the week. Seas will begin to increase to 11-13 feet late Friday through the weekend. Seas are expected remain relatively small inside the Southern California Bight, although steep and choppy wind waves will occur Wednesday. High confidence in winds remaining remaining relatively light through Wednesday morning, then northwesterly winds will increase to 20-30 knots across the waters south of Point Conception, including the inner waters. Winds inside the Southern California Bight will decrease late Wednesday night, but SCA level northwesterly winds will continue across the outer waters and expand to the north Thursday through Friday. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...High Surf Advisory in effect until 9 PM PDT Wednesday for zones 340-346. (See LAXCFWLOX). PZ...Small Craft Advisory in effect until 9 PM PDT this evening for zones 670-673. (See LAXMWWLOX). && $$ PUBLIC...Rorke AVIATION...Lewis MARINE...Lewis SYNOPSIS...30 weather.gov/losangeles Experimental Graphical Hazardous Weather Outlook at: https://www.weather.gov/erh/ghwo?wfo=lox