25/853 AM.
Temperatures will remain above normal across all valleys and interior locations through this weekend. Persistent marine layer will keep temperatures on the cooler side for coastal areas south of Point Conception through at least Thursday. After another warm up on Friday max temperatures will end up ten to 15 degrees above normal and will continue through the weekend. Cooler and cloudier conditions are likely early next week with rain possible mid week.
(tdy-Fri), 25/915 AM.
***UPDATE***
The marine layer, which was around 2000 feet in the LA Basin, sloping down to around 1000 feet along Central Coast, will keep temperatures near the coast much cooler again today. Clouds and fog made it into the LA/Ventura valleys as well but another warm day there is expected with highs in the 80s, around 15 degrees above normal. Dense fog did make it up the Central Coast this morning and offshore flow has weakened so temperatures there are expected to be 5-10 degrees cooler than yesterday. Still above normal but cooler than the last couple days.
Overall, still expecting a general warmup everywhere Thu/Fri. Coastal areas south of Pt Conception will take at least til Friday or Saturday to see much warming and even then confidence is low due to uncertainty with the gradient. Deterministic models are indicating a light 1-2mb offshore flow while the ensembles, which have generally performed much better, are as high as 3.5. It will likely take all of that 3.5 to get dispatch the marine layer and bring the warming that models are indicating. Interior parts of the coast and valleys stand a much better chance for warming by the weekend with highs in the 80s and 90s, possibly 95-98 in the warmest valleys by Saturday. Some increasing northerly winds in the mountains and southern Santa Barbara County Thursday but mostly below advisory levels.
***From Previous Discussion***
A 1300 ft marine layer and decent onshore flow to the east along with negligible offshore flow from the north will allow for a robust marine layer cloud pattern to sit atop of most of the csts and most vlys south of Pt Conception. Offshore flow will limit the amount of low clouds N of Pt Conception to the immediate coasts of western SBA county. The capping inversion is not as strong as it was ydy, but the onshore push in the afternoon is stronger so clearing will likely be similar to ydy and maybe even a little later. Max temps will be very similar to ydy's values except for the Central Coast where weaker offshore flow will bring an earlier seabreeze and 10 to 15 degrees of cooling.
A little upper level support will join with a small offshore push from the north and produce gusty winds through the I-5 corridor and NW portion of the Antelope Vly. The gusts will likely come in just under advisory levels.
The upper high south of New Mexico with strengthen and expand on Thursday. This will push hgts over Srn CA up to 583 dam. The onshore flow will persist as will the low clouds south of Pt Conception. Max temps will be fairly similar to today's except for few degrees of warming over the mtns and most vlys due to the rising hgts. The SBA south coast will also warm with a little downsloping off the Santa Ynez Range.
Friday's forecast is a little tricky and is very dependent on the sfc pressure gradients. The current forecast favors a decent offshore push, minimal marine layer and 4 to 8 locally 10 degrees of warming. The higher rez mdls are are just starting to forecast for this time period and do not show nearly as much offshore flow. If this trend continues, Friday's forecast will need to be cooled and marine layer clouds reintroduced.
(Sat-Tue), 25/225 AM.
Srn CA will be under an area of strengthening SW flow through the period. Hgts will fall from about 579 dam on Saturday morning to ~568 dam on Tuesday morning. Gradients will slowly become more and more onshore through the period. There will be plenty of night through morning low clouds with patchy fog. The lowering hgts and increasing onshore flow will allow for decent vly coverage. Skies, otherwise will be mostly clear over the weekend but there will be increasing mid and high level clouds starting on Monday.
The lowering hgts, marine layer, increasing onshore flow and increasing clouds will all conspire to lower temps starting Sunday (Saturdays temps will be similar to Friday's). The current forecast call for 2 to 4 degrees of cooling Sunday, 3 to 6 degrees on Monday and 5 to 10 additional degrees on Tuesday. By Tuesday max temps will be at or below normal for the first time since March 4th.
A chance of rain will develop Tuesday and continue into Wednesday as a trof/weak front is forecast to move through the area. Both AI-mdls have kept this timing but now show much less rainfall potential. Current ensemble and AI based forecasts now show that this will be a quarter to half inch storm. This could change and while timing confidence is high the rainfall forecast is not.
25/1801z.
At 17Z at KLAX, the marine layer was 1300 feet deep. The top of the inversion was at 2800 feet with a temperature of 20 C.
High confidence TAFs for KPRB, KPMD, & KWJF.
Moderate confidence in TAF for KSBP and KSMX with a 20-30 percent chc of LIFR/VLIFR conds 12Z-17Z Thu morning, otherwise VFR conds expected.
Moderate confidence in remaining TAFs. Timing of CIG/VSBY restrictions may be off +/- 2 hours. Cig hgt could be off by +/- 200 ft.
KLAX, Moderate confidence in TAF. SCT conds on Thu could arrive as late as 20Z. Low clouds could return as early as 26/01Z. No significant east wind component is expected.
KBUR, Moderate confidence in TAF.
25/834 AM.
High confidence in Small Craft Advisory (SCA) winds and steep seas expanding through Wednesday over offshore waters from the Central Coast down to San Nicolas Island. It will remain windy through Thursday Night and will likely weaken quickly and significantly on Friday. The winds peak Wednesday afternoon through Thursday morning, when there is a 40% chance for low-end Gales.
The nearshore waters of the Central Coast will see some of those winds and seas, with a 60% chance of reaching SCA during the peak.
High confidence in the rest of the waters being without a SCA through at least Friday.
Patchy dense fog will affect the near shore waters off the Central Coast this morning.
Ca, NONE. PZ, Small Craft Advisory in effect until 9 PM PDT Thursday for zone 645. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PDT Friday for zones 670-673-676. (See LAXMWWLOX).
