Area Forecast Discussion
Issued by NWS Los Angeles, CA
Issued by NWS Los Angeles, CA
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525 FXUS66 KLOX 312131 AFDLOX Area Forecast Discussion National Weather Service Los Angeles/Oxnard CA 231 PM PDT Fri May 31 2024 .SYNOPSIS...31/151 PM. A cooler than normal weather pattern will continue across much of the area through the weekend as a persistent marine layer remains in place with strong onshore flow. A warming trend is expected next week, especially for the interior portions of the area Wednesday and Thursday as onshore flow weakens. && .SHORT TERM (TDY-MON)...31/206 PM. Weak troughing along the West Coast has returned, increasing onshore flow and deepening the marine layer. Sounds like a broken record but with the possible exception of a few days next week this may last for quite some time. Onshore flow is about 2mb stronger than yesterday and models show a slight increase again tomorrow as well. With the deep marine layer visibilities in most areas (except the mountain slopes) will be quite good, but clearing times will be late, and for some coastal areas possibly not at all. High temperatures for coast and valleys will be 4-8 degrees below normal while most low temperatures will be slightly above normal thanks to the persistent cloud blanket. Far interior areas will be 2-5 degrees above normal during the day and slightly more at night thanks to overnight breezes from the strong onshore flow that will keep the lower levels well mixed. A few degrees of warming and slightly earlier marine layer clearing are likely Sunday and Monday as the trough starts to shift east and high pressure begins to assert itself over the west. Still below normal temperatures for coast/valleys but not as much so. .LONG TERM (TUE-FRI)...31/230 PM. High pressure will be building over the western states starting Tuesday and lasting through Wednesday and possibly Thursday before another trough of low pressure returns for later next week into next weekend. The warmup will be brief, and mostly confined to the interior areas, but will likely result in our first 100 degrees readings in quite some time. Based on all the ensemble runs from the NAEFS and EPS there is a greater than 80% chance of 100 degree or higher temperatures in the Antelope Valley on Wednesday with lower chances Tuesday and Thursday. Similar chances for far interior SLO County. Closer to the coast it`s a much different story. Though warming is expected for all areas, the amount of warming will be much more moderate, and for coastal areas high will likely only top out in the lower 70s at most with some beaches staying cloudy much of the day. Onshore flow is expected to weaken and be at its lowest point Tuesday and Wednesday but SST`s are still only around 60 which will keep temps from warming up too much. Ensembles still indicating around 60% chance of low 90s in the warmer valley areas like Woodland Hills Wednesday, but likely in the mid to high 80s otherwise. Troughing returns later next week into next weekend for a likely return of June gloom conditions and well below normal temperatures for coast and valleys. && .AVIATION...31/1755Z. At 17Z at KLAX, the marine layer was 2500 ft deep. The top of the inversion was at 3800 feet with a temperature of 19 deg C. Moderate to hi confidence in the 18Z TAFs. Low clouds over the coast and adjacent vlys will clear to near the coast by late this morning, with MVFR conds likely persisting thru the afternoon at KOXR, KCMA, KSMO and KLAX. IFR/MVFR cigs will likely spread back inland tonight and affect all coast and adjacent vly airfields and continue into late Sat morning. The timing of the dissipation and onset of low clouds may be off +/- an hour or two, with the largest uncertainty of the onset of low clouds tonight for KBUR and KVNY. For KPRB, KWJF and KPMD, there is hi confidence VFR conds will continue thru the TAF period. Gusty SW winds will affect the desert airfields for most of the fcst period. KLAX...Moderate to hi confidence in the 18Z TAF. MVFR cigs will likely persist this afternoon with only a 20% chance of the low clouds scattering out. There is a 50% chance of IFR cigs early this evening, otherwise MVFR cigs will continue tonight thru Sat afternoon. No significant east wind expected. KBUR...Moderate to hi confidence in the 18Z TAF. VFR conds are expected for the most part into this evening, then IFR cigs should move in by 07Z. The cigs will improve to MVFR by 11Z and continue into late Sat morning. The timing of the onset of the low clouds and changes in flight cats tonight may be off +/- an hour or two. && .MARINE...31/123 PM. In the northern outer waters zone (PZZ670), winds and seas are expected to reach Small Craft Advisory (SCA) levels (80% chance) this afternoon and continue through at least Sunday night. Elsewhere in the outer waters, winds and seas are expected to remain below SCA levels thru Saturday morning. SCA level winds are likely (70% chance) in the central zone (PZZ673) starting Saturday afternoon then spread to the southern zone (PZZ676) Saturday night before continuing through at least Sunday night. SCA conds are likely (70% chance) in all the outer waters Mon and Monday night before gradually subsiding Tuesday. Conds will likely be below SCA levels for Wed. In the inner waters N of Pt. Sal, there is a 30% chance of SCA level winds Saturday afternoon. SCA conds are likely (60-70% chance) during the afternoon/eve hours Sat night through Mon. Conds should then be generally below SCA levels Tuesday and Wednesday. In the inner waters S of Pt. Sal, there is a 50%-60% chance of SCA winds in western portion of the SBA Channel during the afternoon and evening hours Saturday through Sunday. Otherwise, conds over the inner waters should be below SCA levels through Wednesday. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...Small Craft Advisory in effect until 3 AM PDT Monday for zone 670. (See LAXMWWLOX). Small Craft Advisory in effect from 2 PM Saturday to 3 AM PDT Monday for zone 673. (See LAXMWWLOX). && $$ PUBLIC...MW AVIATION...Sirard MARINE...Sirard SYNOPSIS...Hall weather.gov/losangeles Experimental Graphical Hazardous Weather Outlook at: https://www.weather.gov/erh/ghwo?wfo=lox