25/354 PM.
A low pressure system will bring cool temperatures, morning drizzle, and gusty winds to the beaches, mountains, and deserts Tuesday through Thursday. Winds will be the strongest Tuesday afternoon and evening. Friday into early next week a warming trend is likely, with temperatures reaching above normal by Sunday.
(tdy-Thu), 25/230 PM.
A strong low pressure system, for this time of year, is currently off the coast of Washington State and is poised to drop down into central California with an inland track. The low will be centered over the Central Valley late Tuesday through Thursday as the latest forceast models have trended the system further south. The storm and will drop 500 mb heights over SoCal and bring cold air advection, energetic northwesterly flow aloft, and instability to the region.
The northwest flow aloft, strong onshore surface gradients, and cold air advection will support gusty winds across the area. Wind Advisories are in effect Tuesday afternoon and evening for the Central Coast, southwestern Santa Barbara County, the Ventura County Beaches, and the Antelope Valley and adjacent foothills (See NPWLOX for more details).
Temperatures will cool to 5-10 degrees below normal Tuesday through Thursday, mostly in the low 60s to low 70s (except mid 70s in the desert on Tuesday). High clouds will increase and a deepening marine layer may see enough cold air aloft to yield patchy morning low clouds at times. However widespread drizzle is possible anywhere that marine layer clouds forms, especially south- facing foothills. The closer proximity of the system will bring some instability to the area, thus there is up to a 15 percent chance of a thunderstorm or heavy shower. The great chances will be across interior mountains and valleys of San Luis Obispo, Santa Barbara, and Ventura Counties Wednesday and Thursday afternoon into evening. Gusty winds, brief heavy rain and cloud- to- ground lightning look to be the main threats should a thunderstorm occur.
(Fri-Mon), 25/203 PM.
The low pressure system is expected to progress eastward by Friday and clear out the region. Behind the low 500 mb heights will trend upwards with generally zonal flow aloft through the weekend. Temperatures will warm each day Friday through Monday. Over the weekend expect highs within a few degrees of normal (low 70s to low 80s for coast and valleys), increasing further to mid 70s to upper 80s next Monday. Onshore surface pressure gradients will likely continue Friday and Saturday, with chances for offshore flow starting Sunday which will contribute to the warming trend and reduce the coverage of marine layer low clouds and fog in the mornings.
25/1726z.
At 1609Z at KLAX, the marine layer was 2900 ft deep. The top of the inversion was at 4000 ft with a temperature of 13 C.
High confidence in VFR TAFs for desert airfields (KPMD & KWJF).
Moderate confidence in remaining sites. Timing of flight cat changes may be off +/- 2 hours and minimums by one category. Marine layer -DZ is possible when CIGs are present.
KLAX, Moderate confidence in TAF. Arrival and clearing times of MVFR CIGs should be accurate within +/- 2 hours of current forecast. CIGs most likely to rise above 2,000ft threshold between 13Z-16Z Tuesday. No significant easterly wind component is expected.
KBUR, Moderate confidence in TAF. No wind issues expected.
25/209 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. By Tuesday afternoon, high confidence in winds and seas increasing to SCA levels across all outer waters through at least Wednesday night. GALE WARNING goes in effect Tuesday afternoon through Tuesday night. Followed by SCA conditions through early Thursday. Thereafter, conditions are likely to fall below SCA levels for a short-time, before returning later Friday into the weekend.
For the Inner Waters north of Point Sal, moderate 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. GALE WARNING goes in effect Tuesday afternoon through Tuesday night. From late Wednesday night through Thursday night, conds should drop below SCA levels.
For the Inner Waters south of Point Conception, moderate confidence in current forecast. From this afternoon through tonight, SCA level W to NW winds are expected across the Santa Barbara Channel, around the Channel Islands, and into Santa Monica Channel during the evening hours. GALE WARNING goes in effect for the Santa Barbara Channel Tuesday afternoon through Tuesday night. Local Gale Force winds could occur nearshore Anacapa island during this timeframe. SCA level winds could linger into Wednesday especially across the channel. Otherwise, expecting conditions to fall below SCA levels thereafter.
Ca, Wind Advisory in effect from 2 PM to 10 PM PDT Tuesday for zones 340-341-346>348-354. (See LAXNPWLOX). High Surf Advisory in effect from 5 PM Tuesday to 5 PM PDT Wednesday for zones 340-346. (See LAXCFWLOX). Wind Advisory remains 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 8 AM to 3 PM PDT Tuesday for zones 645-670-673. (See LAXMWWLOX). Gale Warning in effect from 3 PM Tuesday to 3 AM PDT Wednesday for zones 645-650-670-673-676. (See LAXMWWLOX). Small Craft Advisory in effect until 1 AM PDT Tuesday for zones 650-655-673-676. (See LAXMWWLOX). Small Craft Advisory in effect from 11 AM to 3 PM PDT Tuesday for zone 650. (See LAXMWWLOX). Small Craft Advisory in effect from 10 AM to 3 PM PDT Tuesday for zone 676. (See LAXMWWLOX).
