31/1259 PM.
Stagnant pattern through Friday, with below normal temperatures, coastal clouds, and moderate Sundowner winds. Several potential scenarios for the Labor Day weekend, with anything from benign conditions possible, tropical rain, to hot offshore winds.
(tdy-Thu), 31/111 PM.
Multiple large troughs of low pressure will drive the weather through the week. The core of the energy and moisture will stay far enough to the north to not be concern with any rain or strong winds, but it will maintain below normal temperatures. To clarify however, with this being the hottest time of the year, below normal temperatures does not mean it is time to dust off the jackets. It will still feel warm, but thankfully not hot like it was last week. Tropical moisture will stay away from the region as well so it will also not feel as muggy as it did last week. With ocean temperatures still in the 70s however, it will still feel more humid than usual.
A deep marine layer (2,000+ feet) will continue through the week as well, and should deepen a little more tomorrow as the trough sags to the south. Would expect a spot or two to see drizzle in the morning where the clouds develop, especially near the Central Coast foothills. Solid night through morning low clouds are most likely on the Central Coast, but coverage to the south should remain spotty thanks to the warmer ocean temperatures, despite the marine layer being just as deep. It is impossible to predict exactly where those random spots of clouds will form.
Sundowner winds will continue each night over southwest Santa Barbara County and flirt with an Advisory each time. Tonight looks just under Advisory levels, while Tuesday and Wednesday night look just over.
(Fri-Mon), 31/140 PM.
Little change expected on Friday compared to the first half of the week.
All eyes remain focused on the Labor Day holiday weekend period. A Hurricane is likely to develop by Wednesday or Thursday from the clump of clouds currently just off the Baja coast. Once it forms, it will likely move to the northwest through Saturday and towards southern California. The big question is where will it head after Saturday. Some deterministic models, like the current GFS, keeps the storm moving northward and right through southern California by Monday or Tuesday. Others, like the deterministic ECMWF, show the storm turning to the west and never even sniffing California. These are just two of many projections, but they do represent the two extreme scenarios between a major rain and wind event and little to nothing. Peering into the ensemble solutions, they suggest that the heavy rain scenario is the least likely outcome (5-10% of the 100 projections have 2+ inches of rain). The completely dry scenario comprises 20-30% of the solutions. Which means in terms of rain, the most likely outcome is for some light rain impacting the holiday weekend. The wind story is similar, with a low but non-zero chance of strong east winds causing fire and downed tree concerns. With all that said, this is definitely a period to monitor with a range of outcomes on the table. Due to the rarity of this storm, expecting there to be a lot of uncertainty even as we get to the weekend, but hopefully some details will come more into focus by mid-week once the storm actually form.
There is growing confidence for significant impacts at the coast however. Unless the storm takes a full left turn after Saturday, the south swell will be pumping through Tuesday, especially considering the swells from the current Hurricane Karina also still around. The evening high tides are also expected to be near 7 feet by Monday. The most likely scenario would result in high surf during a busy holiday weekend and moderate coastal flooding on south facing beaches. If the storm gets closer to the coast, those impacts will be amplified.
31/1626z.
At 16Z at KLAX, the marine layer was 2000 feet deep. The top of the inversion was at 2500 feet with a temperature of 21 Celsius.
High confidence on VFR conditions through Tuesday at KWJF KPMD.
Window for VFR conditions to start at KPRB (17-19Z) KSBP (18-20Z) KSMX (18-20Z).
High confidence in IFR/MVFR conditions tonight through Tuesday at KPRB KSMX KSBP. Low confidence for KSBA KOXR KCMA KSMO KLAX KLGB KBUR KVNY. Any of these sites could see MVFR ceilings, but if they do, will likely only last 1-3 hours.
KLAX, Moderate confidence in VFR conditions by 18Z. High confidence in VFR conditions to follow through at least 06Z. Low confidence after that, but the majority of the 06-18Z period should be VFR with possible periods of MVFR. High confidence in an east winds staying under 8 knots.
KBUR, High confidence in VFR conditions through at least 08Z. There is a 30% chance of 1-3 hours of MVFR ceilings, with very low confidence on timing.
31/142 PM.
High confidence that Small Craft Advisory (SCA) winds and short period seas will be most common from Point Sal to San Nicolas Island through the majority of the week. The western Santa Barbara Channel will be flirting with SCA each evening. The nearshore Central Coast waters will likely stay under SCA through Tuesday, with a window of low-end SCA Wednesday and Thursday.
Ca, Beach Hazards Statement in effect until 3 PM PDT this afternoon for zones 354-362-366. (See LAXCFWLOX). PZ, Small Craft Advisory in effect until 2 AM PDT Tuesday for zone 650. (See LAXMWWLOX). Small Craft Advisory in effect until 6 AM PDT Wednesday for zones 673-676. (See LAXMWWLOX).
