Area Forecast Discussion
Issued by NWS Los Angeles, CA
Issued by NWS Los Angeles, CA
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638 FXUS66 KLOX 212049 AFDLOX Area Forecast Discussion National Weather Service Los Angeles/Oxnard CA 149 PM PDT Sat Sep 21 2024 .SYNOPSIS...21/149 PM. A warmer and drier pattern will establish through Monday as high pressure aloft will build over the region. A warmer air mass will likely remain in place through much of next week away from the coast with the hottest daytime temperatures forecast for Monday. Onshore flow will remain in place through the period and keep night through morning low clouds and fog in the forecast. && .SHORT TERM (TDY-TUE)...21/136 PM. A slow clearing marine layer kept coast and valleys relatively cool today, mostly 60s and 70s, while interior areas warmed up considerably. At least some of that interior warming will migrate towards the valleys and coast Sunday into next week as building high pressure aloft and weakening onshore flow combine to dramatically lower the marine layer depth. Highs Sunday expected to rise 10 degrees over today across the valleys and 2-5 degrees closer to the coast. The marine layer, which was 3000` this morning south to 1000` north, is expected to be cut in half by Sunday and Monday, resulting in much earlier clearing at least for inland areas. Another 3-6 degrees of warming expected Monday bringing warmest valley highs to the mid to high 90s, roughly 4-8 degrees above normal. A slight increase in onshore flow is expected Tuesday afternoon that will cool temperatures a couple degrees across coast and valleys but either little change or slight warming across the interior. .LONG TERM (WED-SAT)...21/148 PM. Overall very quiet weather expected across southwest California the rest of next week with most of the ensemble based guidance maintaining temperatures at near to slightly above normal through the period. However, there is increasing spread in the ensemble solutions later next week resulting is decreasing confidence in the forecast. None of the solutions show rain south of the Bay area, but there are some solutions with a deeper trough along the West Coast Thu-Sat with cooler than normal temperatures. && .AVIATION...21/1755Z. At 1611Z at KLAX, the marine layer was 3100 ft deep. The top of the inversion was at 3800 feet with a temp of 20 C. High confidence in TAFs for KPRB, KPMD, and KWJF. There is a 10% chance for LIFR cigs/vsbys at KPRB between 10Z and 15Z. Moderate confidence in KLAX, KLGB, KSMO, KBUR, and KVNY. There is a 10-20% chance that KLAX, KSMO, and/or KLGB do not clear this afternoon. There is a 20% chance for LIFR cigs at KLAX/KSMO and a 30% chance at KBUR/KVNY between 07Z and 16Z. There is a chance cigs may arrive +/- 2 hours from current fcst. Moderate confidence for remaining TAF sites. There is a 30% chance KSBA, KOXR, and/or KCMA do not clear this afternoon. There is a chance for VLIFR cigs/vsbys at KSMX (40%) and KSBP (20%) between 05Z and 16Z. Minimum flight cat may be off +/- 1 cat at all sites once cigs arrive, and arrival of cigs may be off +/- 2 hours from current fcst. KLAX...Moderate confidence in TAF. There is a 20% chance that clouds do not clear this afternoon. There is a 20% chance for OVC003-OVC005 between 07Z and 16Z. There is a 10% chance cigs scatter by 17Z Sunday. No significant east wind component expected. KBUR...Moderate confidence in TAF. There is a 30% chance at of cigs OVC002-OVC005 between 07Z and 16Z and vsbys between 1SM and 3SM. There is a 20% chance cigs arrive +/- 2 hours from current fcst. && .MARINE...21/117 PM. For the Outer Waters (Central Coast south to San Nicolas Island), moderate to high confidence in winds and seas remaining below Small Craft Advisory (SCA) level thru Wednesday, except for a 30-40% chance for low end SCA level wind gusts near Pt Conception Sunday evening thru late night. Then there a 30-50% chance of SCA level wind gusts beginning late Wednesday afternoon and evening, then higher confidence for Thursday and Friday, which will also lead to building steep seas. For the inner waters along the Central coast, high confidence in conds remaining below advisory levels through early Thursday, with moderate confidence in increasing winds in the afternoon Thursday and Friday. For the Inner waters south of Point Conception, moderate to high confidence in conditions remaining below SCA levels through Wednesday. There is a 20-30% chance of local low end SCA gusts in the far western portion of the Santa Barbara Channel and the San Pedro Channel Sunday afternoon. Additionally, there is a 30-40% chance of SCA level winds across the western portions Wednesday thru Friday in the afternoon thru evening hours. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...NONE. && $$ PUBLIC...MW AVIATION...Lewis MARINE...Lewis SYNOPSIS...Hall weather.gov/losangeles Experimental Graphical Hazardous Weather Outlook at: https://www.weather.gov/erh/ghwo?wfo=lox