02/915 PM.
Gusty northwest to northeast winds will continue through the week. Otherwise, clear skies and near to slightly above normal temperatures are expected, peaking this coming weekend when gusty Santa Ana winds are likely. Mainly dry conditions are expected through at least early next week, though some light showers are possible in the Grapevine region Wednesday night into Thursday morning.
(Mon-Thu), 02/840 PM.
Current satellite imagery this evening showing patches of low clouds developing across the Central Coast. Overnight, expecting low clouds to fill in across portions of the LA Basin and interior valleys of San Luis Obispo County. As of 8 pm, pockets of gusty northwest to north winds across the district, mostly focused across southern Santa Barbara county and the I-5 corridor. Current wind advisories in effect tonight are expected to expire at 3 am. On Tuesday, the low level flow will shift to the northeast across the interior portions of LA/Ventura counties. Offshore winds will likely gust in the 25 to 35 mph range across the LA/Ventura county mountains and adjacent foothills/valleys, below advisory levels. This offshore pressure trend will bring a slight warming trend and less wind overall to the region on Tuesday.
A trough will move into northern California Wednesday and into southeastern California Wednesday night into Thursday morning. This will swing gradients towards onshore during the day, but turning sharply offshore to the north on Wednesday night into Thursday. The increased north-south offshore pressure gradients combined with increasing upper level wind support will likely bring stronger and more widespread northerly winds to the region Wednesday night into Thursday. Many north-south corridors will likely see wind advisories during this time period as we get closer to the event, with wind gusts of 35 to 50 mph common. The northerly winds are expected to expand into the San Fernando Valley and west side of LA county (along I-405 corridor) coast. A few areas may see localized damaging wind gusts to 60 mph such as I-5 corridor, Highway 33 corridor in Ventura mountains, western Antelope Valley foothills, and eastern Santa Ynez range (especially near Montecito Hills), and High Wind Watches may need to be issued as we draw closer to the event. The trough will also contain some moisture which will likely manifest in some light rain or snow showers Wednesday night into Thursday morning on the north facing slopes from the Grapevine area west to the interior Santa Barbara Mountains. Amount will be generally a quarter inch or less with an inch or two of snow possible above 4500 feet.
Windy and cool conditions will continue into Thursday for the mountains and higher valleys. Downsloping flow off the mountains will moderate temperatures closer to sea level but a moderate onshore breeze in the afternoon will keep temperatures around 70 plus or minus 3 degrees.
(Fri-Mon), 02/240 PM.
The tricky pattern gets trickier Friday into the weekend as models are indicating another cutoff low dropping into southern California, this one approaching from the northeast and potentially cooler with 500mb hights dropping to the 550s. There is less moisture with this one so little to no chance for any precip, but increasing chances for gusty Santa Ana winds, and potentially damaging winds as a northeasterly upper jet of 130kt aligns favorably with winds closer to the surface. Will see how this pattern evolves over the coming days but if this pattern continues in the models there is the potential for widespread warning level winds across the LA/Ventura Counties Saturday.
Another day of offshore flow Sunday winds spreading into areas north of Pt Conception as well, but not quite as windy as Saturday for LA/Ventura Counties.
Some models are indicating a rapid warm up Saturday and Sunday with the offshore flow but there is a large error window with this pattern based on the uncertainty of the upper low movement so confidence in the temperature forecast remains low at this time.
Models are indicating the upper low will linger into early next week with a small potential for some wrap around moisture from the southeast, but most solutions keep any rain south of LA County.
03/0558z.
At 23Z over KLAX, the marine layer depth was 1000 feet deep at KLAX. The top of the inversion was near 2500 feet with a temperature around 16 degrees Celsius.
There is a chance for IFR/MVFR ceilings tonight into Tuesday morning at KPRB and KSBP(70%) KSMX (30%) KSBA (20%) KOXR (30%) KCMA (20%) KSMO (50%) KLAX (60%) KLGB (70%) KBUR (20%). Otherwise high confidence in VFR. Weaker winds expected on Tuesday. LLWS 5-10 knots possible at KSBP tonight.
KLAX, 60% chance of ceilings 008-012 in the 09-18Z window. Otherwise high confidence in VFR through Tuesday. East winds are likely Tuesday morning, but high confidence in staying below 8 knots.
KBUR, 20% chance of IFR ceilings 12-15Z Tuesday, otherwise high confidence in VFR.
02/914 PM.
Moderate to high confidence in the current forecast. Higher confidence exists in the forecast for winds. Less confidence in exists in the forecast for seas. There is a moderate chance that seas could be up to 1-3 feet higher than forecast, especially between Wednesday and Friday.
Widespread SCA level winds may diminish some this morning across portions of the waters, but are expected to rapidly increase again this afternoon. SCA level winds will affect the outer waters and the nearshore waters along the Central Coast through this afternoon. Then, widespread strong SCA conditions (winds and seas) will develop tonight through Friday. There is a high (50-70 percent) chance of GALES for the outer waters and nearshore along the Central Coast from early Wednesday through late Thursday night. There is also a 40-60 percent chance of GALES affecting the Santa Barbara Channel Wednesday night through Thursday night, with a possible lull Thursday morning.
An offshore flow pattern will set up Friday through Sunday, with a moderate (30 to 50 percent) chance of SCA levels winds inside the southern California bight and the nearshore waters along the Central Coast, with winds likely peaking on Saturday.
Ca, Wind Advisory remains in effect until 3 AM PST Tuesday for zones 349-351>353-376>378-381. (See LAXNPWLOX). PZ, Small Craft Advisory in effect until 3 PM PST Wednesday for zones 645-650. (See LAXMWWLOX). Gale Watch in effect from Wednesday afternoon through Thursday morning for zone 645. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PST Tuesday for zone 655. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PST Wednesday for zones 670-673-676. (See LAXMWWLOX). Gale Watch in effect from Wednesday afternoon through late Thursday night for zone 670. (See LAXMWWLOX). Gale Watch in effect from late Tuesday night through late Thursday night for zones 673-676. (See LAXMWWLOX).
