Marine Weather and Tide Forecast for Vandenberg AFB, CA

.SHORT TERM (THU-SUN)...16/813 PM.

***UPDATE***

Mostly clear skies covered the forecast area this evening, with little change expected overnight.

Northerly pressure gradients were increasing this evening with gusty northerly winds developing over portions of the Santa Lucia Mtns and the Santa Ynez Mtns. There were also strong and gusty NW winds noted along the I-5 corridor and other portions of the the northern L.A County mtns this evening in response to the passage of an upper level trof to the N. Overnight and into Fri morning, the winds will switch to N to NE and increase over VTU/L.A Counties and affect the usual Santa Ana wind corridors Fri morning into the afternoon. Wind Advisories are in effect for many of these areas for various times. Please see the latest Non- Precipitation Weather Message (LAXNPWLOX) for further details.

The winds along the Central Coast have diminished this evening so the Wind Advisory there was cancelled. Otherwise, no significant changes to the zone forecast this evening.

***From Previous Discussion***

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.

.LONG TERM (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.

AVIATION
17/0748Z.

At 06Z at KLAX, there was no marine layer nor an inversion.

Moderate confidence in TAFs, except high confidence in KPRB, KSMX, and KSBP.

Timing of wind changes may be off +/- 2 hours, with N-NE gusts off by +/- 5kt at any point through the morning. Lgt to moderate LLWS & turbulence is possible over and near mountainous terrain through 00Z Sat, especially across Los Angeles and Ventura counties.

There is a 40% chance of MVFR cigs at KSMO, KLAX, and KLGB at some point through 17Z Fri, however, conds may scatter and reform frequently due to the patchy nature of the marine layer clouds.

KLAX...Moderate confidence in TAF. There is a 40% chance of BKN012-022 conds through 17Z Fri, and conds may scatter and reform frequently. There is a 60% chance of east wind component reaching 7-8kts between 10Z and 17Z, with a 30% chance of reaching 10 kts.

KBUR...Moderate confidence in TAF. Wind changes may be off by +/- 2 hours, with a 20% of no northerly winds through the period.

MARINE
16/938 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. Through late tonight, current Gale Warnings look on track, and will likely need SCAs following the gales for high seas. 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. 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 tonight. 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.

LOX WATCHES/WARNINGS/ADVISORIES
CA...Wind Advisory remains in effect from 7 AM this morning to 2 PM PDT this afternoon for zones 88-354-355-358-369-371-372-374-375. (See LAXNPWLOX).
Wind Advisory remains in effect until 8 AM PDT this morning for zone 342. (See LAXNPWLOX).
Wind Advisory remains in effect until 3 AM PDT early this morning for zones 349-351>353-376>378. (See LAXNPWLOX).
Wind Advisory remains in effect from 4 AM early this morning to 2 PM PDT this afternoon for zones 379-380. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 3 AM PDT early this morning for zone 645. (See LAXMWWLOX).
Small Craft Advisory in effect from 6 AM this morning to noon PDT today for zones 650-655. (See LAXMWWLOX).
Gale Warning in effect until 3 AM PDT early this morning for zones 670-673-676. (See LAXMWWLOX).