25/1152 PM.
Marine layer clouds with patchy fog will reoccur each night from the coasts to the coastal valleys, expanding into the valleys over the weekend. Temperatures will trend cooler, with below normal temperatures through Sunday. A slow warming trend will begin on Monday.
(tdy-Sun), 26/941 AM.
***UPDATE***
Morning satellite shows the marine layer in place along the coast with the top of the layer around 2500 feet, although it is very slowly beginning to erode in places. Mid- to high clouds can also be seen shifting into southern CA. As pressure heights continue to fall, mid- to high level clouds will continue to increase further southward. The deepening marine layer due to offshore flow, along with the increasing mid- to high clouds, will result in cooling daytime temperatures through Sunday, after which temperatures remain fairly stable through late next week. Highs will largely run in the 70s further inland, with a handful of locations reaching the low 80s, and coastal locations generally warming into the mid- to upper-60s.
As the pressure gradient tightens, winds will begin to increase this evening, peaking on Saturday. WIND ADVISORIES have been issued for the Antelope Valley and Western Antelope Foothills from 11 AM PDT today through 5 AM PDT Sunday for gusts to around 50 mph. The NBM 24-hour max wind gust for these two regions, along with a short stretch of I-5 rest of today and Saturday is 40 to 45 mph with a much broader area of max gusts to 35 mph. Additional WIND ADVISORIES are in effect for the Santa Barbara SW coast for sundowner winds 5 PM PDT this evening through 3 AM PDT tomorrow and again Saturday night into Sunday morning. Offshore northwest winds winds will reach 30 mph with gusts up to 50 mph. The Santa Barbara beaches will experience breezy onshore winds during these same timeframe, with gusts ranging 25 to 35 mph.
***From Previous Discussion***
The next three days (and beyond) will be dominated by a persistent night through late morning (or even afternoon) low cloud pattern. This pattern is the result of unusual cyclonic flow generated by a series of upper lows moving through the PACNW along with strong onshore flow (~9mb peak). Low clouds will arrive in the evenings and will be slow to clear with some clouds lingering into the afternoon across west facing nearshore areas.
Another effect of the strong onshore flow will be the gusty winds through the passes and canyons of LA County into the Antelope Valley. Look for persistent gusty winds, with isolated strong gusts, in the afternoon to evening hours through Sunday. As usual, the strongest winds will be over the interior, especially the Antelope Valley.
The combination of falling hgts, strong onshore flow and a deep persistent marine layer will bring cooling to most areas today through Sunday. Most cst and vly max temps will only be in the 70s through the period with mid to upper 60s across the beaches and a smattering of 80 or 81 degree readings in the warmest vly locations. These max temps are 3 to 6 degrees under normal for the csts and 6 to 12 degrees for the vlys.
(Mon-Thu), 26/159 AM.
Not much change in the June Gloom forecast for the end of the month and into July. A series of upper lows moving through the PACNW will keep cyclonic flow aloft through the period. Mdt to stg onshore flow will continue through the period xcp on Mon when there will be a noticeable relaxation of the onshore gradients.
Look for the night through morning low cloud pattern to continue although it should be a little less intense in coverage and duration on Monday.
Look for 2 to 4 degrees of warming Monday with the weaker onshore flow, but all that warming will be lost Tuesday as the onshore flow strengthens again. Not much change on Wednesday and then a little more warming on Thursday as the upper level troffing is forecast to weaken. Max temps will remain many degrees under normal through the period.
26/1746z.
At 1630Z at KLAX, the marine layer was 2600 ft deep. The top of the inversion was at 3500 feet with a temperature of 18 C.
High confidence in VFR TAFs for desert airfields (KPMD & KWJF).
Moderate confidence in the remainder of the TAFs. Timing of flight cat changes could be off +/- 2 hours and CIG heights +/- 300 ft.
KLAX, Moderate confidence in TAF. Arrival of MVFR CIGs around 012 expected to occur 27/02Z (+/- 2 hours). 15% chance CIGs initially arrive at IFR 008. CIGs expected to gradually lift breaking 2000 ft threshold sometime between 16/13Z-16Z. 25% chance east wind component reaches 7-8 kts 16/12Z-16Z.
KBUR, Moderate confidence in TAF. Arrival of IFR CIGs around 008 should be accurate within +/- 2 hours of current forecast. CIGs should lift to MVFR 010-015 around 13Z. No wind issues expected.
26/936 AM.
Small Craft Advisory (SCA) level wind gusts are expected to expand into the inner waters focused across the western and southern Santa Barbara Channel and north of Point Sal today, peaking Saturday before gradually diminishing through Monday. Local gusts may approach 35 kt near Pt with a 30 percent chance of Gale conditions across the central part of the Santa Barbara Channel Saturday evening. There is a 30 percent chance of SCA conditions expanding into the southern inner waters along and south of Point Mugu/Malibu Saturday afternoon to evening.
Seas will near 10 ft Saturday evening through at least Monday morning focused across the outer waters. Beyond, conditions look to quiet down a bit through mid next week.
Ca, Wind Advisory remains in effect from 5 PM this afternoon to 3 AM PDT Saturday for zones 349-351. (See LAXNPWLOX). Wind Advisory in effect from 5 PM Saturday to 3 AM PDT Sunday for zones 349-351. (See LAXNPWLOX). Wind Advisory remains in effect until 5 AM PDT Sunday for zones 381-383. (See LAXNPWLOX). PZ, Small Craft Advisory in effect until 3 AM PDT Sunday for zone 645. (See LAXMWWLOX). Small Craft Advisory in effect from 3 PM this afternoon to 3 AM PDT Saturday for zone 650. (See LAXMWWLOX). Small Craft Advisory in effect from 11 AM Saturday to 3 AM PDT Sunday for zone 650. (See LAXMWWLOX). Small Craft Advisory in effect until 9 AM PDT Monday for zones 670-673-676. (See LAXMWWLOX).
