Area Forecast Discussion
Issued by NWS Los Angeles, CA
Issued by NWS Los Angeles, CA
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335 FXUS66 KLOX 162143 AFDLOX Area Forecast Discussion National Weather Service Los Angeles/Oxnard CA 243 PM PDT Mon Sep 16 2024 .SYNOPSIS...16/919 AM. Much cooler than normal temperatures will continue through the next several days, before warmer conditions return for next weekend. It will be windy at times today and tonight. There is a small chance of rain or drizzle today and a better chance on Wednesday. Areas of low clouds will be common over the coast and coastal valleys, with areas of clearing each afternoon. && .SHORT TERM (TDY-THU)...16/242 PM. The main story through Thursday will be continued cool and breezy conditions with night to morning low clouds and drizzle or light showers at times. A deep moist layer is helping to fuel cumulus clouds and even a few sprinkles in our mountains. This is good news for firefighting efforts, especially for the Bridge Fire. However, low end advisory level winds continued across the ridge top and favored canyons and slopes leading into the Antelope Valley. Advisory level winds will also likely develop into the Oxnard Plain to western Santa Monica mountains and eastern Ventura valleys by this afternoon. It will also be breezy southwest Santa Barbara County, but likely (70-80 percent) below advisory levels. Winds for most areas will drop off sometime late this afternoon or evening. Low cloud forecast is challenging tonight as deep moisture in place limits radiated cooling processes necessary to reform marine layer clouds with the best shot for low clouds and patchy fog across the Central Coast where a weak inversion has managed to remain in place. Guidance has trended slower and further west with our second early season storm to pass through the region Wednesday into Thursday. This is a colder and somewhat wetter scenario with light rain or drizzle possible just about anywhere in southwest California at some point during this time frame. The cold core low pressure system may be dynamic enough to support isolated thunderstorms for interior Ventura, Santa Barbara, and San Luis Obispo Counties sometime Thursday with the most likely window in the afternoon. Rainfall amounts will generally be light and under a quarter of an inch, although locally higher amounts are possible for Santa Lucia mountains in northwest San Luis Obispo County and the eastern foothills and lower mountains of Los Angeles County, as well as in any thunderstorms that do form. Breezy northwest to onshore winds are likely Wednesday into Thursday with the most wind prone areas potentially reaching advisory levels. .LONG TERM (FRI-MON)...16/242 PM. Moderate forecast confidence for the upcoming weekend with two main scenarios in play. Most likely scenario (80% chance): Significant warming and drying this weekend, with temperatures reaching the 90s to around 100 for many inland areas. Generally light offshore breezes will be possible each morning. This would likely increase fire weather concerns. Less likely scenario (20% chance): The warming trend is less intense, with highs mostly in the 70s and 80s. Low clouds and fog may linger along the coast, especially the Central and LA coasts. Regardless of the weekend scenario: Next week is likely to be warmer than normal, suggesting a prolonged period of above-normal temperatures may begin as early as this weekend. && .AVIATION...16/1815Z. At 1548Z at KLAX, there was a moist layer up to 5000 feet deep. There was no inversion. High confidence for TAFs at KPMD and KWJF. Low confidence in all remaining TAFs. Sites south of point conception will likely have cigs between 020 and 050 when cigs return tonight thru tomorrow. There is a chance for LIFR cigs/vsbys at KSMX (30%) and KSBP (10%) between 10Z and 16Z. There is a 20% chance for IFR-MVFR cigs at KPRB from 10Z to 15Z. Minimum flight cats may bounce frequently during the period at all sites. Arrival time of cigs may be off +/- 5 hours from current forecast. KLAX...Low confidence in TAF. Cigs will likely vary between BKN020 and BKN040 thru 18Z tomorrow. Cigs expected by 07Z. There is a 40% chance that cigs could arrive as soon as 02Z. Cigs > BKN035 could arrive as early as 13Z. No significant east wind component expected. KBUR...Low confidence in TAF. Cigs will likely vary between BKN020 and BKN040 through 17Z. Arrival and dissipation of cigs may be off by +/- 4 hours from TAF. && .MARINE...16/209 PM. For the Outer Waters (Central Coast to San Nicolas Island), moderate to high confidence in the forecast. For the northern zone (Pt Piedras Blancas to Pt Sal) winds are likely to remain below SCA level until Tues afternoon, then there is a 60-80% chance of SCA level winds developing Tues afternoon thru Wed morning. From Wed afternoon thru late Sun, moderate confidence in winds remaining below SCA level, with a 30-50% chance of SCA winds Fri thru Sun, with best chances Sun. For the southern zones (Pt Sal to San Nicolas Island) moderate to high confidence in SCA level winds persisting into early Wednesday, with a lull possible Tuesday morning. There is a 40-60% chance of SCA winds continuing thru late Wed. There is a 30-60% chance of SCA level winds Thurs thru Sun, with best chances Fri afternoon thru late night. For the Inner Waters off the Central Coast. High confidence winds will remain sub advisory level thru tomorrow morning, then there is a 60-80% chance of SCA winds in the afternoon thru evening hours Tues. Moderate confidence in winds being sub advisory Wed thru Sunday, with lowest confidence in the afternoon thru evening hours Fri thru Sun. For the Santa Barbara Channel, high confidence in Gale Force thru late tonight, then rapidly decreasing to below SCA level. Steep, choppy seas and strong rip currents can be expected thru late tonight. There is a 40-70% chance in SCA level winds returning Tues and Wed afternoon thru late night, with higher confidence Tues. From Thurs to Sun, There is a 20-50% chance of SCA level winds in the afternoon thru evening hours, with highest confidence Fri. For the nearshore waters off the Los Angeles and Orange County coasts, SCA level winds will continue throughout much of the zone. In the northwest portion of the zone from Malibu west to the Channel Islands and as far south as Santa Barbara Island, high confidence in Gales thru late tonight. Seas will be choppy in this area, and exposed beaches may see strong rip currents. Winds will quickly drop off to below SCA levels overnight into early Tues. Moderate to high confidence in winds remaining below SCA level Tues afternoon thru Sun. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...Wind Advisory in effect until 9 PM PDT this evening for zones 354>357-369-374. (See LAXNPWLOX). Beach Hazards Statement in effect through late tonight for zones 354-362-366. (See LAXCFWLOX). Wind Advisory now in effect until 9 PM PDT this evening for zones 379-380-382. (See LAXNPWLOX). Wind Advisory remains in effect until 9 PM PDT this evening for zones 381-383. (See LAXNPWLOX). PZ...Small Craft Advisory in effect from 3 PM Tuesday to 3 AM PDT Wednesday for zones 645-650-670. (See LAXMWWLOX). Gale Warning in effect until 3 AM PDT Tuesday for zones 650-655. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PDT Wednesday for zones 673-676. (See LAXMWWLOX). && $$ PUBLIC...Munroe AVIATION...Lewis MARINE...Lewis SYNOPSIS...JB/RM weather.gov/losangeles Experimental Graphical Hazardous Weather Outlook at: https://www.weather.gov/erh/ghwo?wfo=lox