24/839 AM.
May Gray low clouds and fog will be widespread across the coasts and valleys each night through morning period. Some cooling is expected over the next couple days, and well below normal temperatures Monday through Thursday. Additionally areas of gusty afternoon and evening winds are expected, strongest Tuesday.
(tdy-Wed), 24/215 PM.
Weather will be generally mild for at least the next few days, as areas of gusty winds will be the most impactful feature. Highs through Monday will be in the upper 60s to upper 70s, except for 80s in the deserts. Starting Tuesday, a strong low pressure system will dig into the Great Basin, bringing very low 500 mb heights (for May), cold air advection, and energetic northwesterly flow aloft. Thus temperatures Tuesday and Wednesday will drop to 5-10 degrees below normal, mostly in the low 60s to low 70s (except mid 70s in the desert on Tuesday).
Forecast models indicate that marine layer clouds may either be slow to form or not form at all tonight through Monday morning, as a result of increasing northwest winds aloft. The greatest chances for clouds will be along the Central Coast. Starting Tuesday, high clouds will stream into the area. While marine layer clouds are likely to form across most coasts and valleys, the inversion may be weakened by the cold air aloft (and the high clouds), thus low clouds may be patchy at times and afternoon clearing may be more rapid.
Winds will trend upwards for Monday and increase further still on Tuesday as a result of the upper level jet setting up over the region and cold air advection (sinking motion). Wind Advisories have been issued for Tuesday into Tuesday night for the beaches of San Luis Obispo County, southwestern Santa Barbara County (NW direction), and the Antelope Valley and western foothills (SW direction). Additional Wind Advisories may be needed for the eastern Antelope Valley foothills, and the Ventura and Western Santa Barbara County beaches on Tuesday. There is also a 20 percent chance that a wind advisory will be needed for Monday night for southwestern Santa Barbara County.
Southwesterly flow will occur at the surface south of Point Conception, as an eddy will form in response to the strong northwesterly winds across the coastal waters and Central Coast. This flow pattern will likely produce fairly widespread drizzle that will be enhanced by south-facing slopes. Drizzle is most likely Monday night through Tuesday morning, though any accumulations will be under 0.10 inches. Additionally, there is a chance of few showers for interior north- facing mountains, especially northern Ventura County to eastern LA County.
(Thu-Sun), 24/216 PM.
The low pressure system is expected to remain in place over the Great Basin through Thurday. Thus little change in appreciable weather conditions is expected for Thursday compared to Wednesday, except winds will be much weaker (due to less cold air advection and weaker winds aloft).
Friday through Sunday temperatures will trend upwards as the low travels to the east, becoming within a few degrees of normal over the weekend (highs in the low 70s to low 80s for coast and valleys). Moderate strength onshore surface pressure gradients will continue, thus some coverage of marine layer stratus is likely each night and morning, and onshore afternoon/evening winds will continue for the Antelope Valley.
24/1754z.
At 1745Z at KLAX, the marine layer was 3000 feet deep. The top of the inversion was at 4300 feet with a temperature of 15 degrees Celsius.
High confidence in KWJF and KPMD. For all other sites, moderate confidence in forecasts as flight category changes could be up to 2 hours off.
KLAX, Moderate confidence in the 18Z TAF. There is a 20 percent chance of mvfr cigs lingering through the afternoon/evening hours. No significant easterly wind component is expected.
KBUR, Moderate confidence in the 18Z TAF. here is a 10 percent chance of mvfr cigs lingering through the afternoon/evening hours.
24/159 PM.
For the Outer Waters, moderate to high confidence in current forecast. Through Monday morning, high confidence in winds and seas remaining below Small Craft Advisory (SCA) levels. Winds will increase to SCA levels Monday afternoon for the waters south of Point Sal to San Nicholas Island, then after a brief lull Tuesday morning, high confidence in both winds and seas increasing to SCA levels Tuesday afternoon through at least Wednesday night for all the outer waters. Additionally, there is a 30-40% chance of Gale force winds Tuesday night. For Thursday afternoon and Thursday night, conds are likely to drop below SCA levels across the waters.
For the Inner Waters north of Point Sal, moderate to high confidence in current forecast. Through Monday afternoon, high confidence in winds and seas remaining below SCA levels. There is a 30% chance of SCA level winds Monday afternoon and evening. For Tuesday through early Wednesday, high confidence in a combination of SCA level winds (strongest in the afternoon and evening hours) and seas. There is a 40% chance of SCA winds and seas Wednesday afternoon through evening. Additionally, there is a 20-30% chance of Gale force winds Tuesday afternoon and especially Tuesday night. T Then late Wednesday night through Thursday night, conds should drop below SCA levels.
For the Inner Waters south of Point Conception, moderate to high confidence in current forecast. Through Monday morning, high confidence in winds and seas remaining below SCA levels. Monday afternoon through night, there is a 50-60% chance of SCA level NW to W winds across the Santa Barbara Channel, around the Channel Islands, and into the Santa Monica Channel. On Tuesday and Tuesday night, there is a 40-60% chance of SCA level winds across the western half of the Santa Barbara Channel, and a 30-40% chance of SCA winds over PZZ655 Tuesday night. Otherwise, moderate to high confidence in winds and seas remaining below SCA levels.
Ca, Wind Advisory in effect from 2 PM to 10 PM PDT Tuesday for zones 340-341. (See LAXNPWLOX). Wind Advisory in effect from 6 PM Tuesday to 6 AM PDT Wednesday for zones 349-351. (See LAXNPWLOX). Wind Advisory remains in effect from 11 AM Tuesday to midnight PDT Tuesday night for zones 381-383. (See LAXNPWLOX). PZ, Small Craft Advisory in effect from noon Tuesday to 3 AM PDT Wednesday for zones 645-670. (See LAXMWWLOX). Small Craft Advisory in effect from 3 PM Monday to 3 AM PDT Tuesday for zones 650-673-676. (See LAXMWWLOX).
