Area Forecast Discussion
Issued by NWS Los Angeles, CA
Issued by NWS Los Angeles, CA
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526 FXUS66 KLOX 110608 AFDLOX Area Forecast Discussion...UPDATED National Weather Service Los Angeles/Oxnard CA 1108 PM PDT Fri May 10 2024 .SYNOPSIS...10/126 PM. A quiet weather pattern is expected through early next week with near normal temperatures and no rain except possibly some light showers over the mountains this afternoon. Increasing night and morning low clouds are expected across coast and valleys as onshore flow increases. Mostly minor day to day changes in temperatures are expected through Sunday, then cooling possible Monday and Tuesday. && .SHORT TERM (FRI-MON)...10/923 PM. ***UPDATE*** Marine layer clouds and onshore sea breezes kept coastal areas were cool today, with temperatures in the low- to- mid 60s. Inland valleys and deserts were much warmer, with highs in the upper 70s to mid 80s. Instability caused by the upper level low circulating over Las Vegas, lead to a thunderstorm this evening over the San Gabriel Mountains, and 0.04 inches of rain was recorded near Mount Wilson. Tonight the marine layer is expected to spread as far inland as the San Fernando Valley and all the way into the San Gabriel Foothills. The areas with the best chance of clear skies tonight are the Santa Clarita Valley and high elevation mountain areas above 3500 ft. Tomorrow expect slightly warmer temperatures across the region, by around 2 to 5 degrees. Afternoon mountain thunderstorms will be possible again tomorrow (5% chance). Conditions will be less favorable than they were today because the upper low will move further away from the region towards the east. Forecast was adjusted with slight temperature increases for inland areas and minor cloud cover adjustments. ***From Previous Discussion*** Otherwise, more of the same for southwest California. Marine layer has finally filled in along the Central Coast and has been very slow to clear elsewhere along the coast. Onshore trends to north and especially the east are likely the culprit and we may be looking at several more days of this coming up. There is a little weak upper ridge that will follow the current trough later Saturday into Sunday that may result in some brief lowering of the marine layer depth and allow for earlier clearing and a few degrees of warming, but subtle changes like are always low confidence, and given the time of year and the upper pattern it`s more likely low clouds will be a mainstay for awhile, with some days struggling to clear at the beaches, especially from Malibu north. .LONG TERM (TUE-FRI)...10/208 PM. The next weak upper low that arrives later this weekend is expected to linger through Wednesday, leading to a slow decline in daytime temperatures and likely a deeper, farther inland, and slower clearing marine layer. Models have also been consistent showing increasing onshore flow to the east during this period. The NAEFS gradients table shows around a half degree of increase each day through May 18, though the deterministic GFS shows a sharp decline starting next Thursday and actually turning lightly offshore next weekend. Very low confidence in this though as the global models are showing a much slower weakening trend in the gradients, which would go along with the upper level grand ensemble mean pattern showing a weak trough over the area later next week. && .AVIATION...11/0608Z. At 0530Z at KLAX, the marine layer was 2400 feet deep. The top of the inversion was at 3000 feet with a max temperature of 20 C. Moderate confidence in TAFs. Good confidence that clearing today will be similar to ydy (Friday). Flight cat transitions may be off by +/- 90 minutes. KLAX...Moderate confidence in TAF. IFR-MVFR transition may be occur anytime between 1530Z and 1700Z. There is a 25 percent chc of SCT conds 22Z-01Z tomorrow afternoon. No significant easterly wind component is expected. KBUR...Moderate confidence in TAF. VFR to MVFR transition may occur anytime between 15Z and 17Z. Good confidence that VFR transition will occur between 17Z and 19Z. && .MARINE...10/747 PM. For the Outer Waters, moderate to high confidence in current forecast. Today through Saturday afternoon, high confidence in winds and seas remaining below Small Craft Advisory (SCA) levels. Saturday evening there is a 60% chance of SCA wind for the outer waters south of Point Conception. For Sunday through Monday night, there is a 50-70% chance of SCA winds. Then, SCA conditions are not expected through Wednesday. For the Inner Waters north of Point Sal, high confidence in current forecast as winds and seas are expected to remain below SCA levels through Wednesday. For the Inner Waters south of Point Conception, moderate to high confidence in current forecast. Through Wednesday, winds and seas will remain below SCA levels for most areas. The only exception will be the western half of the Santa Barbara Channel where there is a 20% chance of SCA wind Saturday evening, and a 30-40% chance of SCA winds Sunday night and Monday. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...Small Craft Advisory in effect from 9 PM Saturday to 3 AM PDT Sunday for zones 673-676. (See LAXMWWLOX). && $$ PUBLIC...MW/Schoenfeld/ASR AVIATION...Rorke MARINE...Cohen/Schoenfeld SYNOPSIS...MW weather.gov/losangeles Experimental Graphical Hazardous Weather Outlook at: https://www.weather.gov/erh/ghwo?wfo=lox