.SHORT TERM (SUN-WED)...15/200 PM.

High-amplitude upper troughing will remain anchored over the western states going into this week. Satellite loops depict significant energy aloft digging through the west side of a deep upper trough along the Pacific Coast, causing the upper vort center to quickly deepen off the Oregon coast toward northern California. By Monday, this vort center will begin an eastward trajectory across central California, as a shortwave trough quickly advances through the base of its surrounding large area of midlevel cyclonic flow.

The progression of this impulse will provide the upper support necessary for winds to continue increasing through tonight, especially for areas south of Point Conception, in proximity to the midlevel speed maximum enhanced around the shortwave trough.
The gusty winds will continue through Monday night, before upper support translates eastward thereafter. Wind Advisories remain in effect through Monday evening for the Antelope Valley and nearby western foothills, where southwest winds 20-30 mph gusting to 45 mph are expected. In addition, enhanced winds will extend farther upstream through the interior slopes of the San Gabriels tonight through Monday evening in response to the progression of stronger momentum aloft. The Wind Advisory has been expanded to include the San Gabriels, as well as the eastern Antelope Valley foothills, where gusts up to 50 mph will be of concern. In addition, the strongest low-level mass response to the progressive shortwave trough will bring terrain-channeled flow through the Santa Barbara Channel eastward to the Ventura County coast and nearby coastal valleys, warranting Wind Advisories in these areas for gusts up to 45 mph. There will be gusty winds over the Santa Ynez Range and the Santa Barbara County South Coast tonight through Monday night, though the overall westerly-flow orientation and lack of a stronger pressure gradient provide limited confidence in Advisory level wind gusts occuring. However, there is a 30% chance for the Wind Advisory to be expanded to include these areas generally south of Point Conception in later forecasts. Winds should be decreasing by Tuesday morning as stronger flow aloft departs the region, with areas of gusty winds returning by Wednesday in association with the next reinforcing vort max.

With the cold core aloft being closest to the area on Monday, Monday high temperatures will be 10-20 degrees below normal in most areas, generally in the 60s and 70s. Highs on Tuesday are forecast to increase a few degrees as heights aloft rebound behind the departing shortwave trough and first vort max, and then fall again by a degree or two for Wednesday as height falls overspread the region with the next reinforcing vort max.

The combination of the deepening moist layer and differential cyclonic vorticity advection ahead of the first vort max will support drizzle and light rain showers spreading across the region tonight into Monday morning. The greatest chance for measurable rain will be along the coastal slopes of the Transverse Ranges owing to upslope-flow enhancements, where up to a quarter inch of rain may fall. Elsewhere, rainfall amounts should be generally a tenth of an inch or less. Rain will end by later in the day Monday, and then return as early as Wednesday in advance of the next reinforcing vort max.

Clouds will remain abundant for the rest of today, with slow and partial clearing ongoing. The moist-layer depth has already increased to 4500 ft at KLAX, and additional deepening is expected over the next day in response to ascent ahead of the approaching vort max. This will continue to reinforce marine stratus over the coasts and well inland across the coastal valleys to the nearby coastal slopes, with only slow and partial clearing later this afternoon. Clouds will be reinforced tonight, before cooling at the top of the moist layer on Monday may completely mix out clouds causing early-day clearing. There is substantial uncertainty regarding cloud coverage and clearing trends on Tuesday and Wednesday, though night through morning low clouds should be prevalent especially near the coast -- as moist-layer depths are boosted by the reduced midlevel heights that get further reduced for Wednesday in advance of the next vort max.

.LONG TERM (THU-SUN)...15/200 PM.

Deep upper troughing will persist over the region late this week, as a reinforcing vort max tracks southward over coastal California amid broad cyclonic flow across the western states.
Another round of very light showers and gusty winds will be possible continuing into Thursday from Wednesday, with well- below normal temperatures across the area on Thursday. Thursday high temperatures will only be in the 70s in most places, with readings in the 60s near the beaches. Temperatures will be warming by next weekend, though there is some uncertainty regarding the onset timing of more significant warming owing to phasing differences between model solutions. However, by next weekend, highs in the 80s to lower 90s should be common areawide, as an amplified upper ridge moves into the region from the east Pacific.

The sharpness of height gradients aloft -- surrounding the reinforcing vort max -- do not appear as significant as those associated with the earlier-week disturbance, and wind headlines do not appear likely at this time. However, coasts and coastal valleys of Ventura County vicinity northeastward through the high terrain across Los Angeles County may experience gusty winds Wednesday into Thursday, and there is a 30% chance for Wind Advisories to become necessary -- especially if the upper low were to trend deeper. Otherwise, marine stratus will be prevalent across much of the region from the coasts to the coastal slopes ahead of the reinforcing vort max through Wednesday night, before potentially scouring out later in the week and becoming confined to areas near the immediate coast.

AVIATION
16/0106Z.

Around 00Z, a weak marine layer was around 4000 feet deep at KLAX. The top of the marine inversion was near 5000 feet with a temperature around 16 degrees Celsius.

Low confidence 00Z TAFs for coasts and coastal valleys. Timing of flight changes may be off by 3 hours and more than one flight category at times. There is a 20-50 percent chance of -DZ/-SHRA focused with vsbys between 2-6SM between 06Z-18Z except locally earlier especially for KSBP and KSMX.

Low confidence in KPRB with a 40 percent chance that VFR conds prevail through the period.

There is a 20-30 percent chance of MVFR cigs between 10-18Z for KPMD with otherwise high confidence for the desert TAFs.

KLAX...Low confidence in 00Z TAF. There is a 20% chance of vsbys between 2SM and 4SM due to drizzle between 06Z and 15Z. Cigs may become >030 by 14Z. No significant east wind component expected.

KBUR...Low confidence in 00Z TAF. There is a 20% chance of brief cigs 008-009 and/or vsbys 2-4SM due to drizzle between 07Z and 16Z.

MARINE
15/139 PM.

For the Outer Waters (Central Coast to San Nicolas Island), moderate to high confidence in the forecast. For the northern zone (Pt Piedras Blancas to Pt Sal), winds should remain near or above Small Craft Advisory (SCA) level throughout the day until late tonight. Then, winds are likely to remain below SCA level until Tues afternoon, where there is a 50-60% chance of SCA level winds thru early Wed morning. From Wed afternoon thru late Sat, moderate confidence in winds remaining below SCA level, with the highest chances in the afternoon thru evening hours Fri and Sat.
For the southern zones (Pt Sal to San Nicolas Island) moderate to high confidence in winds persisting thru late Tues or early Wed.
Moderate to high confidence in winds then picking back up to SCA level Wed afternoon thru late, especially from Pt Conception to San Nicolas Island. From Thurs thru Sat, moderate confidence in winds remaining under SCA thresholds, with a 20-30% chance of SCA winds Sat afternoon.

For the Inner Waters off the Central Coast. High confidence in SCA level winds lasting thru late tonight, with local gusts to 35 kt possible in the far northern portion of the zone. High confidence winds will remain sub advisory level thru Tues midday, then there is a 30-50% chance in SCA winds in the afternoon thru evening hours Tues thru Wed, with best chances Tues. Moderate to high confidence in winds being sub advisory Thurs thru Sat.

For the Santa Barbara Channel, high confidence in winds reaching SCA level, but moderate confidence in timing. Winds may increase as early as this evening, but higher confidence in late tonight or early tomorrow. High confidence in GALES across the channel, specifically from Santa Cruz Island east to the coast beginning tomorrow mid day and lasting thru at least late Tues. An upper level trough passing overhead will lead to an abrupt enhancement of the surface level winds, leading to very choppy seas and strong rip currents. Winds will decrease into the early morning hours Tues, with moderate confidence in them remaining above SCA level thru late Wed, especially in the afternoon and evening.
Then, there is a 20-40% chance of SCA level winds Thurs thru Sat, with best chances Fri and Sat.

For the nearshore waters off the Los Angeles and Orange County coasts, SCA level winds will develop in the morning throughout much of the zone. In the northwest portion of the zone from Malibu west to the Channel Islands, and as far south as Santa Barbara Island, winds will likely (70-80% chance) rapidly increase to GALE FORCE by midday. Seas will be choppy in this area, and exposed beaches may see strong rip currents. Winds will drop off to SCA level late Mon/early Tues. Moderate to high confidence in winds remaining below SCA level Tues afternoon thru Sat.

LOX WATCHES/WARNINGS/ADVISORIES
CA...Wind Advisory in effect from noon Monday to midnight PDT Monday night for zones 354>357. (See LAXNPWLOX).
Wind Advisory in effect from midnight tonight to midnight PDT Monday night for zones 379-380-382. (See LAXNPWLOX).
Wind Advisory remains in effect until 9 PM PDT Monday for zones 381-383. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 3 AM PDT Monday for zones 645-670. (See LAXMWWLOX).
Small Craft Advisory in effect from 3 AM to noon PDT Monday for zone 650. (See LAXMWWLOX).
Gale Warning in effect from noon Monday to 3 AM PDT Tuesday for zones 650-655. (See LAXMWWLOX).
Small Craft Advisory in effect from 9 AM to noon PDT Monday for zone 655. (See LAXMWWLOX).
Small Craft Advisory in effect until 9 AM PDT Tuesday for zones 673-676. (See LAXMWWLOX).