873 FXUS66 KLOX 161621 AFDLOX Area Forecast Discussion...UPDATED National Weather Service Los Angeles/Oxnard CA 921 AM PDT Thu May 16 2024 Updated Aviation Discussion .SYNOPSIS...16/852 AM. Strong onshore flow and a persistent marine layer will remain in place through the middle of next week. Night through morning low clouds and fog will be a staple of the forecast, clearing to the beaches each afternoon. Breezy to gusty onshore winds will occur each afternoon and evening across the interior valleys and adjacent foothill areas. && .SHORT TERM (TDY-SAT)...16/911 AM. ***UPDATE*** May Gray conditions remain firmly in place across southwest California with strong onshore flow and a marine layer depth around 3500 feet across the LA Basin, sloping to around 2000 feet along the Central Coast. Clearing is expected across the coastal valleys by afternoon but clearing chances decrease closer to the coast. Not expecting any significant changes to this for the next several days. Highs today and for the next week or so are expected to be 4-8 degrees below normal across coast and coastal valleys. For interior areas highs will be 3-6 degrees above normal through this weekend, then turn below normal next week. ***From Previous Discussion*** Away from the coast into the interior portions of the area, breezy to gusty onshore winds will create elevated fire weather conditions during the afternoon and evening hours when warmer daytime temperatures and drier humidities combine with breezy to gusty winds. Over the next several days, winds will be marginal for advisory levels, but as the upper-level trough of low pressure draws closer to the area over the weekend, winds could approach advisory levels. EPS solutions suggest wind gusts approaching advisory levels on Saturday afternoon and evening, and again on Sunday afternoon and evening at KPMD and KWJF. Lingering instability from the trough could bring a few isolated showers to the mountains, but it will likely just be some clouds over the mountains this afternoon and evening. Moisture parameters are down much from yesterday, but PoPs are non-zero over the mountains this afternoon and evening. As the trough offshore move closer to the region, a slight chance of showers and thunderstorms over the Ventura and Santa Barbara County mountains could reenter the forecast over the weekend during the afternoon and evening hours. Stay tuned to the latest as this could be a wrinkle that changes the forecast. .LONG TERM (SUN-WED)...16/349 AM. A deep marine layer depth and strong onshore flow is likely to continue into early half of next week, keeping the forecast near persistence into at least Tuesday. The forecast changes little as a deep marine layer and expansive low clouds field could bring the threat of night through morning drizzle along the South Coast of California. The forecast ensemble members are highlighting the potential for a weak trough of low pressure dropping south down the coast between Wednesday and Thursday. Gusty northerly winds appear in a majority of the EPS ensemble members at KSDB and KSBA, but there is some spread in the ensemble members into late next week. Pattern recognition in the deterministic solutions would confirm the possibility of a tightening northerly gradient for late next week. && .AVIATION...16/1620Z. At 16Z at KLAX, the marine layer was 3000 ft deep. The top of the inversion was 5000 feet with a temperature of 20 C. Moderate confidence in coastal, valley, and mtn-slope TAFs, and high confidence in desert TAFs. Persistent low stratus will bring cig restrictions from the coast to mtn slope areas through much of the forecast period. Expect only slow clearing today, with skies clearing by early this afternoon in the valleys and later in the afternoon across interior sections of the coastal plain. It will likely remain cloudy near the coast, but cigs may rise into the VFR category. Expect similar conds tonight compared to last night, with widespread cig restrictions for all coast, valley and mtn slope areas. Timing of cig restrictions could vary +/- 3 hours of current forecasts. VFR conditions are expected for desert sites. KLAX...Moderate confidence in TAF. There is a 20-30% chance that cigs will scatter out between 21Z and 02Z. No significant easterly wind component is expected. KBUR...Moderate confidence in TAF. There is a 20-30% chance that cig restrictions will persist thru the day. && .MARINE...16/914 AM. In the Outer Waters, moderate to high confidence in the forecast. There is a 20-30% chance that winds reach Small Craft Advisory (SCA) levels this afternoon and evening -- highest chances in the southern two zones (PZZ673/676). There is a 30% chance of SCA level winds/seas over the entire outer waters Sun night thru Tue. Otherwise SCA conds are not expected. For the Inner Waters N of Pt. Sal, high forecast confidence. Winds and seas are expected to remain below SCA levels thru Tue. In the Inner Waters S of Pt. Conception, moderate to high forecast confidence. There is a 20-30% chance of SCA level winds in the western portion of the SBA Channel this afternoon/evening and again during the afternoons of Mon and Tue. Otherwise, SCA conds are not expected. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...NONE. && $$ PUBLIC...MW/Hall AVIATION...DB/Cohen MARINE...DB/Cohen SYNOPSIS...Hall weather.gov/losangeles Experimental Graphical Hazardous Weather Outlook at: https://www.weather.gov/erh/ghwo?wfo=lox