Area Forecast Discussion
Issued by NWS Los Angeles, CA
Issued by NWS Los Angeles, CA
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540 FXUS66 KLOX 162040 AFDLOX Area Forecast Discussion National Weather Service Los Angeles/Oxnard CA 140 PM PDT Fri Aug 16 2024 .SYNOPSIS...16/139 PM. Aside from night and morning low clouds and fog near the coast, mostly quiet weather is expected through next week. Hazardous heat will be possible next Tuesday or Wednesday for the interior. && .SHORT TERM (TDY-MON)...16/139 PM. Aloft, deep low pressure will remain nearly stationary off the Pacific Northwest coast through early next week, while a midlevel ridge strengthens over the south-central states. Midlevel heights over the local area will change little through early next week, while dry southwesterly flow prevails. At the surface, generally light onshore flow will keep high temperatures a few to several degrees below normal near the coast through early next week, with highs over interior areas of a few to several degrees above normal. Modest offshore pressure gradients for SBA-SMX will facilitate sub-advisory Sundowner winds across southern Santa Barbara County each day. Night and morning low clouds and fog will dissipate by mid-day each day. .LONG TERM (TUE-FRI)...16/139 PM. Early next week, the upper low and an associated trough off the Pacific Northwest coast will weaken and de-amplify. Midlevel height rises over the local area will facilitate the westward extension of the south-central states ridge. In response to these developments, HeatRisk will have the potential to increase to the Moderate to perhaps Major category, with a 30% chance for heat headlines to become necessary on Tuesday or Wednesday over interior areas. Light onshore flow will keep temperatures closer to normal near the coast, where the rising heights should foster shallower marine-layer depths and greater chances for patchy dense fog at night and in the morning. Then for late next week, the latest medium-range model consensus indicates the aforementioned trough and low becoming reinforced with heights aloft falling across the local area. Correspondingly, a cooling trend is expected for Thursday and Friday. In general, dry conditions should prevail through much of next week. However, there is a remote chance (currently less than 10%) for convection to develop over the LA and Ventura County Mountains between Tuesday and Wednesday -- when there will be an opportunity for monsoonal moisture to extend into the area to the south of the aforementioned de-amplifying trough. Despite the somewhat favorable moisture trajectories, larger-scale forcing for ascent should be quite weak, and thus confidence in convective development is currently low. && .AVIATION...16/1756Z. At 1646Z at KLAX, the marine layer was 1300 ft deep. The top of the inversion was 2700 ft with a temperature of 24 deg C. High confidence in 18Z TAFs for KPRB, KBUR, KVNY, KPMD, and KWJF. Moderate confidence in Los Angeles County coastal TAFs. Arrival of cigs may be off +/- 3 hours from current forecasts. Cig/vsby restrictions may bounce between VFR-IFR between 04Z and 10Z. There is a 30% chance cigs arrive by 04Z as IFR. Low confidence in remaining coastal TAFs. Arrival of cigs may be off +/- 4 hours from currents forecast and minimum flight cat may be off by 1 cat at any time after cigs arrive. There is a 30% chance of VLIFR conditions at KSMX and KOXR at any point after cigs arrive. There is a 20% chance KSBP remains VFR thru the period. KLAX...Moderate confidence in the 18Z TAF. There is a 30% chance that cigs below 010 arrive by 04Z and a 20% chance of cigs below 005 with vsbys as low as 4SM between 09Z and 15Z. Flight cats may bounce between VFR-IFR, especially between 04Z and 09Z. There is a 30% chance of VFR conditions by 16Z. No significant east wind component is expected. KBUR...High confidence in 18Z TAF. && .MARINE...16/132 PM. For the offshore waters from the Central Coast to San Nicolas Island (the outer waters), high confidence in SCA level winds for the two southern zones through Monday. For the furthest northern zone, high confidence in SCA level winds through tomorrow morning, with moderate confidence in SCA level winds continuing thru Monday. For the nearshore waters off the Central Coast, moderate confidence in SCA level winds through this evening. Moderate confidence in conditions remaining below SCA levels through Monday. For the Santa Barbara Channel, high confidence in winds below SCA levels through Saturday. Moderate confidence in SCA level winds in the Western Portion of the channel Saturday afternoon and evening. Then, high confidence in winds remaining below SCA levels Sunday thru Monday. In the eastern portion, high confidence in conditions remaining below SCA level through the Monday. For the southern inner waters, high confidence in conditions staying under SCA levels through Monday. With a shallow marine layer, moderate confidence in patchy dense fog with visibilities under 1 nautical mile effecting the Central Coast waters and southern inner waters tonight thru tomorrow morning. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...Small Craft Advisory in effect until 9 PM PDT this evening for zone 645. (See LAXMWWLOX). Small Craft Advisory in effect until 9 AM PDT Saturday for zone 670. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PDT Monday for zones 673-676. (See LAXMWWLOX). && $$ PUBLIC...Cohen AVIATION...Lewis MARINE...Lewis/Kittell SYNOPSIS...Cohen weather.gov/losangeles Experimental Graphical Hazardous Weather Outlook at: https://www.weather.gov/erh/ghwo?wfo=lox