20/805 PM.
Widespread rain will develop Wednesday and continue into Thursday with a chance of thunderstorms. A weak Santa Ana will develop in the storm's wake by the weekend for dry and warmer conditions.
(Tue-Fri), 20/803 PM.
***UPDATE***
Relative calm this evening before the first significant storm of the season arrives Wednesday. Low clouds have spread along portions of the Central Coast and also for areas from the southern SBA County coast to portions of southern VTU County, all out ahead of the approaching storm system over the E Pac. For the rest of tonight, expect clouds to increase in all areas with generally mild overnight lows.
The latest NAM run from this evening was forecasting the main cold front with the storm system will move quickly into the the Central Coast Wednesday morning then into VTU County around midday and into L.A. County Wednesday afternoon. Timing of the system has really not changed much from the morning model runs. Forecast is on track and further details on this system and its expected impacts on southwestern CA are noted below. The current forecast is on track and no evening updates are anticipated.
***From Previous Discussion***
The upper level low continues drop south following 130w, roughly parallel with SLO County but about 400 miles to the west. The system is starting to turn the corner and head east and seems to be on track for a relatively on time arrival Wednesday morning in SLO and Santa Barbara Counties and by afternoon in LA County. On satellite the storm still looks pretty strong with an actively convective center with at least two or three primary rain bands ahead of it. The ENS and GEFS ensemble rain amounts ticked up last night by as much as a half inch and generally held that level with the 12z run this morning. So for this cycle very fer changes have been made to the forecast. A targeted Flood Watch has been issued for southern Santa Barbara County as well as the Santa Monica Mountains and adjacent coastline as models have been indicating the highest rain rates in those areas, around .75" per hour. For the western areas the peak rain rates are expected in the afternoon and evening hours while in Ventura and LA Counties the heaviest rain is expected Wednesday night into Thursday morning. In general, for areas south of Pt Conception, rain amounts are expected to be around 1.5 inches, except as much as 2-3 inches in upslope areas and any areas where thunderstorms develop. Areas north of there closer to an inch, though again higher amounts in storms. Also, there is a small (5% or less) chance of a weak tornado as the upper low moves inland late Wednesday night into Thursday morning. No snow below 8000 feet.
Dry weather will return Friday with a weak or potentially low end moderate Santa Ana event this weekend but much weaker than the last event. Temperatures should warm up quickly into the upper 70s and 80s most everywhere except for the mountains and deserts. Latest models are indicating peak winds around 35 mph across most coast/valley areas in LA/Ventura Counties.
Fun fact: For those curious about rain probabilities in October, the chances for rain on any given day in October is around 7%, which is only 20% lower than in February. And remember we also had a big storm in October of 2025 that dropped just under 1.5" in LA.
(Sat-Tue), 20/129 PM.
A weak to low end moderate Santa Ana event is expected this weekend but much weaker than the last event. Temperatures should warm up quickly into the upper 70s and 80s most everywhere except for the mountains and deserts. Latest models are indicating peak winds between 30 and 50 mph, strongest in the LA/Ventura mountains.
21/0428z.
At 00Z at KLAX, the marine layer was 800 ft deep. The top of the inversion was at 2600 ft with a temperature of 20 C.
High confidence in VFR TAFs at KPMD and KWJF.
Moderate confidence in MVFR conds at times at remaining sites. Timing may be off +/- 3 hours with CIG height +/- 200 ft of TAF.
Rain is expected for most TAF sites between 12Z-22Z, earliest along the Central Coast to KSBA. There is a 10-20 percent chance of TSRA KSBA and north starting around 18Z. TSRA spreads to KOXR and KCMA Wednesday afternoon, and into LA County after 06Z.
KLAX, Moderate confidence in TAF. There is a 30% chc of lower cigs of OVC008. An east wind component up to 5 kt is possible 12-18Z with a 10 percent chance of brief 8 kt.
KBUR, Moderate confidence in TAF. Brief BKN008 conds possible 20/13Z-17Z, becoming likely after 21Z.
20/925 PM.
Expecting showers to move into the coastal waters as early as tonight as the low approaches from the west. Boaters can expect rain and a chance of thunderstorms and isolated waterspouts spreading from west to southeast. With any thunderstorm there is also the threat of lightning, gusty and erratic winds, small hail, and choppy seas. Winds still do not look too impactful, there is a good chance for periods of Small Craft Advisory (SCA) level (including the nearshore waters) southerly winds Wednesday morning through Wednesday evening. As the system leaves the area Thursday, fairly widespread west to northwest SCA winds will impact much of the coastal waters, creating steep, choppy wind waves.
Then a weak to locally moderate Santa Ana Wind event is likely this weekend, with some localized SCA level gusts possible nearshore in favored areas nearshore adjacent to Ventura and LA Counties.
Ca, Flood Watch in effect from 8 AM PDT Wednesday through Thursday afternoon for zones 348>353. (See LAXFFALOX). Beach Hazards Statement in effect through late Thursday night for zones 354-362-366. (See LAXCFWLOX). Flood Watch in effect from Wednesday afternoon through Thursday afternoon for zones 362-369-370. (See LAXFFALOX). PZ, Small Craft Advisory in effect from 11 AM to 8 PM PDT Wednesday for zones 650-655. (See LAXMWWLOX). Small Craft Advisory in effect from 5 AM to 5 PM PDT Wednesday for zone 673. (See LAXMWWLOX).
