.SHORT TERM (THU-SUN)...12/734 PM.

***UPDATE***

The main issues for the evening update are the northerly winds affecting portions of the area, and marine layer cloud coverage.

For winds, there are north winds gusting between 30 to 35 mph as of 700 PM. High resolution models show the winds increasing a bit in the next hour or two, then decreasing. So while local gusts up to 40 mph will be possible in the short term this evening, nothing up to Advisory level is expected. Similar conditions are observed in the Interstate-5 Corridor this evening, although gusts are somewhat stronger, between 33-36 mph. Again, with some increase over the next couple of hours, isolated gusts to 45 mph will be possible, but should not be widespread enough to require an Advisory.

Marine layer clouds are expected to be more extensive than last night, with the most comprehensive coverage over the Central Coast, and also likely over the LA Basin. The Ventura Coast and Santa Barbara South Coast are likely to see low clouds, but the duration could be shorter than in the previously mentioned areas.

***From Previous Discussion***

Quiet and cooler weather conditions are expected for Southwest California through the short term, and in fact through much of the coming week. An upper low moved through the Pacific Northwest, with the associated trough swinging across northern California.
This lowered the heights aloft and effectively ended the long duration heatwave over southern California. Today's highs are expected to lower 6 to 12 degrees compared to Wednesday's highs, with widespread 80s to near 90 away from the coast, and 60s to 70s for coastal areas (coolest along the Central Coast). Temperatures will fluctuate some through the short term, bumping up a few degrees on Friday, especially for the interior as a weak ridge moves through the region. Highs will then lower slightly on Saturday, and more significantly on Sunday as a large low pressure system moves into the Pacific Northwest and southward to northern California, with the upper low extending southward over northern Baja, Mexico. The low center will shift further south toward the Bay Area Sunday night into Monday, bringing a slight chance of some light showers to the forecast area Sunday morning, with a somewhat better chance of light showers again late Sunday night into Monday.

As for winds, there will be some gusty northerly winds late this afternoon and tonight across SW Santa Barbara County, affecting the Santa Ynez Range, and also through the Interstate 5 Corridor.
In both locations, the gusts will be moderate and below Advisory levels with gusts up to 35 mph. Tomorrow and Saturday the flow will shift to onshore in the afternoon to evening hours, with gusts up to 30 mph through the interior mountains and valleys, increasing to 25 to 40 mph on Sunday.

Morning status should be a little more widespread Friday morning thanks to weakening northerly flow, and is expected to spread over the Ventura and Santa Barbara South Coasts and into some of the coastal valleys. Increasing onshore flow may keep some cloud cover lingering near the coast through the afternoon Friday and Saturday, but otherwise clear skies expected.

.LONG TERM (MON-THU)...12/139 PM.

Ensemble solutions and deterministic models continue to show a deepening low pressure system dropping south along the West Coast and into California Sunday, with the upper closed low located near to just northeast of the Bay Area. Both the GFS and EC have much lower heights than the ensemble means by almost 10 dam so the system may not be quite as strong as the deterministic solutions, but either solution would cause cool temperatures across the area through late in the week. At this time, the coolest day looks to be Monday, with most locations showing highs in the 60s to mid 70s. This would be followed by slight warming into Tuesday with temperatures likely to hold steady through later in the week.
Another side effect of the upper low and its proximity to SW California will be a chance of light showers or drizzle late Sunday night into Monday, west and coast of the mountains.

Another upper low will move into northern California on Wednesday, again with a trough extending southward into Baja. While models indicate chances of a bit more rain, the ensembles hint at a drier solution. Some warming may return for the following weekend.

AVIATION
13/0142Z.

Around 00Z, the marine layer depth was around 1300 feet deep at KLAX. The top of the inversion was near 5000 feet with a temperature around 21 degrees Celsius.

High confidence in TAFs for KPMD and KWJF.

Low confidence in TAFs for KPRB where there is a 30-40% chance for VFR conditions thru the period. Moderate to low confidence in remaining TAFs. Minimum flight cat at KBUR and KVNY may be off by one cat once cigs arrive. Arrival time of cigs may be off by +/- 2 hours from current fcst. There is a 20% chance for KSBP to become VLIFR between 08Z and 15Z. There is a 20% chance KSBP remains VFR thru the period. Arrival of cigs may be 1-3 hours later than forecast.

KLAX...Moderate confidence in TAF. There is a 20% chance that cigs arrive between 04Z and 05Z. Cigs may not clear until 20Z.
There is a 30% chance for an east wind component of up to 6-8 kt from 12Z to 17Z.

KBUR...Low to moderate confidence in TAF. There is a 20% chance cigs arrive after 08Z.

MARINE
12/144 PM.

For the Outer Waters from the Central Coast to San Nicolas Island, moderate to high confidence in the forecast. Small Craft Advisory (SCA) winds are likely (50-70%) thru Friday morning.
High confidence in winds remaining below SCA level from late Friday morning thru Sat night. Then, moderate to high confidence in SCA level winds picking back up as early as Sat late night thru Sun early morning (20-30% chance this early) and persisting thru at least late Mon. There is a 20-40% chance of Gales in the southern zone from late Sun thru at least late Mon, with best chances Mon. Steep and choppy seas expected thru at least Friday.

For the nearshore waters off the Central Coast, moderate confidence in the forecast. SCA level winds are expected thru this evening. High confidence in winds remaining below SCA level for most of the weekend. There is then a 50-60% chance of SCA level winds Sun afternoon thru at least Mon, with highest confidence in the afternoon thru late evening hours Mon.

For the Santa Barbara Channel, moderate confidence in the forecast. Winds are will be strongest in the western and southern portions of the channel thru tonight. Then, high confidence in winds remaining below SCA level thru most of the weekend, with a 60-70% chance of winds ramping up to SCA level Sun afternoon and lasting thru at least Mon night, with highest confidence Mon afternoon thru late evening, with a 20-40% chance of Gales occuring during this period, especially for the western and southern portions.

For the nearshore waters off the OC/LA coasts, high confidence in winds and seas remaining below SCA level thru Sun. Then, moderate confidence in SCA level winds occuring Mon in the afternoon thru evening hours, with a 10-20% chance of Gales from the waters off Malibu thru the San Pedro Channel.

LOX WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...Small Craft Advisory in effect until 9 PM PDT this evening for zones 645-650. (See LAXMWWLOX).
Small Craft Advisory in effect until 8 AM PDT Friday for zones 670-673-676. (See LAXMWWLOX).