16/113 PM.
Dry and warmer weather is expected for the remainder of this week. Gusty northerly winds will develop over mountains and Antelope Valley today, shifting to northeast and becoming focused over Los Angeles and Ventura Counties on Friday. There is a chance of rain next Tuesday.
(tdy-Sun), 16/152 PM.
The main forecast issue through Friday is the winds. A cold upper level system moving into the Great Basin will create gusty north to northwest winds across the Antelope Valley and I5 corridor regions through tonight with wind advisories in effect in the mountains. As that storm moves into Utah and Colorado later tonight the upper level winds will veer to the northeast and pressure gradients will rapidly turn offshore setting the stage for a moderate Santa Ana wind event for LA/Ventura Counties. Santa Ana winds will begin in the San Gabriel Mountains probably after 3am, then spread down into the north and west San Fernando Valley near or shortly after sunrise, then eventually spreading through southern Ventura County and the western Santa Monicas by 10am. This will be a pretty quick shot of wind, lasting only a few hours at the coast but closer to 6-10 hours in the mountains. However, peak mountain winds could still reach 60 mph while coast and valleys generally stay in the 20-40 mph range. Some warming will accompany this offshore event, though the warmest day by far will be Saturday with much less wind and highs in the mid to upper 80s in the valleys and mid 70s to mid 80s elsewhere.
Another warm day expected Sunday, though definitely cooling along the coast as offshore flow turns onshore by afternoon bringing a much earlier sea breeze.
(Mon-Thu), 16/223 PM.
Still plenty of uncertainty next week as an even colder upper level low, completely disconnected from the jet stream, slowly wobbles down the West coast. Timing is probably the most uncertain factor due to the low being cut off. There's still about 24 hours of wiggle room with the onset of rain in any one area, the earliest being Monday morning along the Central Coast and Tuesday morning in LA County. There are also still about 20% of the ensemble solutions showing little or no rain south of Pt Conception. Having said that, the most likely outcome is for periods of light rain to develop across most of the area (except possibly the far interior areas) by Tuesday afternoon with minimal impacts. The ensembles means have been pretty steady with the amounts around a half to one inch across SLO County, then dropping to less than a half inch in LA County. However, if the upper low manages to slide all the way down to LA County, given the time of year and the cold air aloft some isolated thunderstorms with heavy rain are possible. And a few inches of snow are possible at higher elevations in the mountains, mainly above 6000 feet.
Lastly, there is a possibility of showers lingering as late as Thursday if the upper low takes a very slow track through the area. This solution would also likely mean that the initial onset of rain would be later as well. It may take well into this weekend before there is any more confidence in the forecast.
16/1753z.
At 17Z at KLAX, there was no marine layer nor an inversion.
Overall, moderate confidence in 18Z TAF Package. Timing of change groups may be off +/- 2 hours. Lgt LLWS & turbulence is possible over and near mountainous terrain across Los Angeles and Ventura counties after 17/10Z.
KLAX, Moderate confidence in TAF. VFR conditions are expected through the forecast period. However, there is a non-zero chance that patchy MVFR CIGs develop between 17/08Z-13Z. There is a 60% chance of east wind component reaching 7-8kts between 10Z and 17Z. 30% chance of reaching 10 kts.
KBUR, Moderate confidence in TAF.
16/216 PM.
For the Outer Waters, moderate to high confidence in current forecast. A combination of (at least) Small Craft Advisory (SCA) level winds and seas are expected through at least Friday morning, and possibly linger through Friday night. This afternoon through late tonight, there is a 50-60% chance of Gale Force winds and a GALE WARNING has been issued for all Outer water zones. Seas will peak Saturday night into early Friday morning and then diminish below advisory levels through Friday. Saturday through Monday, there is a 20-30% chance of SCA level winds.
For the Inner Waters north of Point Sal, moderate to high confidence in current forecast. Through tonight, high confidence in SCA level winds and seas through tonight, with winds strongest during the afternoon and evening hours. There is a 20% chance of GALE force wind gusts across the western portion this evening. Friday through Monday, high confidence in winds and seas remaining below SCA levels.
For the Inner Waters south of Point Conception, moderate to high confidence in current forecast. There is a 60% chc of SCA level winds across the far western portion of the Santa Barbara Channel this afternoon and evening. Otherwise, winds and seas will remain below SCA levels through tonight. Starting early Friday morning, SCA level NE winds will develop from Ventura south to Santa Monica spreading out towards Anacapa Island. From Point Mugu to Malibu on Friday morning, there is a 25% chance for Gale Force winds nearshore especially below any canyons/passes. Saturday through Monday, high confidence in winds and seas remaining below SCA criteria for all southern Inner Waters.
Ca, Wind Advisory in effect from 7 AM to 2 PM PDT Friday for zones 88-354-355-358-369-371-372-374-375. (See LAXNPWLOX). Wind Advisory remains in effect until 9 PM PDT this evening for zones 340-346. (See LAXNPWLOX). Wind Advisory remains in effect from 7 PM this evening to 8 AM PDT Friday for zone 342. (See LAXNPWLOX). Wind Advisory remains in effect from 7 PM this evening to 3 AM PDT Friday for zones 349-351-352. (See LAXNPWLOX). Wind Advisory in effect from 6 PM this evening to 3 AM PDT Friday for zones 353-376>378. (See LAXNPWLOX). Wind Advisory in effect from 4 AM to 2 PM PDT Friday for zones 379-380. (See LAXNPWLOX). PZ, Small Craft Advisory in effect until 3 AM PDT Friday for zone 645. (See LAXMWWLOX). Small Craft Advisory in effect from 6 AM to noon PDT Friday for zones 650-655. (See LAXMWWLOX). Small Craft Advisory in effect until 3 PM PDT this afternoon for zones 670-673-676. (See LAXMWWLOX). Gale Warning in effect until 3 AM PDT Friday for zones 670-673-676. (See LAXMWWLOX).
