29/1037 PM.
A switch to onshore flow will bring two days of noticeable cooling to all areas. Even with the cooling most areas will see above normal temperatures. There will be a slow return of morning low clouds to the coasts. Dry conditions are expected through at least early next week.
(tdy-Sat), 30/736 AM.
***UPDATE***
Latest satellite and surface observations indicate clear skies across the area this morning, although some stratus/fog is working its way south along the coast. As for winds, currently northeasterly gusts of 20-30 MPH are observed in the wind-prone spots.
Forecast-wise for the immediate short term, no issues are expected. The lingering offshore winds will likely increase a bit this morning (per usual diurnal trends), but will weaken by the afternoon with some weak onshore flow developing. So, do not anticipate any need for advisories. As for temperatures, morning TEMP STUDY data indicates a slightly cooler boundary layer. So, with weaker offshore gradients this morning, shifting to onshore this afternoon, coastal and valley areas will be several degrees cooler. However across the mountains and deserts, temperatures will likely bump up a degree or two.
Overall, forecast looks great for the immediate short term. So, no significant updates are expected. For the afternoon forecast suite, attention will be on the gradual return of the marine layer this weekend as well as a chance of some light rain across northern sections the middle of next week.
***From Previous Discussion***
Chamber of Commerce day on tap today with sunny skies and max temps in the 80s and lower 90s. A weak ridge will nose in from the SW and hgts will reach 586 dam. At the SFC there will 2 to 3 mb of offshore flow, which is about half the values it was ydy. The weaker offshore flow will allow an earlier sea breeze and this will bring 5 to 10 degrees of cooling to the coasts and 3 to 6 degrees to the vlys. Despite this cooling max temps will end up 8 to 12 degrees above normal (3 to 6 for the coasts of SLO and SBA counties)
Actual onshore flow develop on Friday and a shallow marine layer will likely form. The weak gradients and under 500 ft marine layer will combine to produce a low lying stratus deck with plenty of dense fog underneath it. Other than the low clouds it will be a sunny day. The onshore flow and marine layer will team up to knock 5 to 10 degrees off of max temps across the csts and vlys. This will cool most of the coastal areas to a few degrees blo normal while the rest of the area will still above normal temps (esp the far interior)
Saturday will be similar to Friday. There will be some offshore trends which may provide a few degrees of warming. There will still be enough of an onshore push to bring low clouds and dense fog to the coastal sections.
(Sun-Wed), 30/1218 AM.
Both the deterministic and ensemble models show unremarkable weather through the xtnd period. Dry SW flow will be over Srn CA through Tuesday and then becomes more cyclonic as a large trof moves into the northern 2/3rds of the west coast. At the sfc there will be a weak diurnal flow pattern becoming stronger onshore on Wednesday.
Skies will be mostly clear through Tuesday save for a night through morning low cloud patter that will affect most of the coasts. Skies should turn partly cloudy (with a deeper marine layer as well) Wednesday as the trof approaches.
Max temps will change little from Saturday on Sunday and will end up 4 to 8 degrees over normal for all areas except the beaches. A slow cooling trend will follow Mon through Wed and by Wed the csts/vlys will be near normal, but the interior will remain several degrees over normals.
The bottom of the trof will pass over the Central Coast on Wednesday afternoon or evening. Right now there is a 20-30 percent chc that it will bring some light rain to the SLO and Western SBA counties.
30/0600z.
At 0505Z at KLAX, there was no marine layer. Thru was a sfc based inversion with a top of 1200 ft and a temperature of 30 C.
Good confidence in TAFs for KLGB and KLAX with a 25 percent chc of VLIFR conds at KLGB and a 15 percent chc of VLIFR conds at KLAX from 10Z-14Z.
High confidence in the remainder of CAVU TAFs.
KLAX, Good in confidence in TAF. There is a 15 percent chance of 1/4SM FG VV002 conds 10Z-14Z. Better confidence in LIFR cig/vis arriving during the 31/06Z-31/12Z time frame. Good confidence in any east wind component remaining below 7 kts.
KBUR, High confidence in CAVU TAF.
30/802 AM.
NW winds 20-30 knots are being observed in the waters off the Central Coast more than 10 NM from shore. These winds will expand in coverage to the east and south, nearshore along the Central Coast and down to San Nicolas Island by this afternoon. Maximum seas will be to the northwestern portion of the coastal waters and top out in the 10-13 foot range. A lull in both wind strength and sea height is possible Friday morning, but periods of Small Craft Advisory (SCA) level winds and seas are expected through the weekend and potentially into early next week. Confidence is low for early next week.
Conditions across the nearshore waters south of Point Conception are expected to remain relatively mild into early next week.
A blanket of dense fog is observed via satellite from Point Piedras Blancas to south of Point Conception, including nearshore areas. The fog will continue to to the south. A more expansive blanket of dense fog is anticipated tonight into Friday morning, including for nearshore waters south of Point Conception.
Ca, High Surf Advisory in effect from 3 PM this afternoon to 3 AM PDT Friday for zones 340-346. (See LAXCFWLOX). PZ, Small Craft Advisory in effect from 3 PM this afternoon to 9 PM PDT this evening for zone 645. (See LAXMWWLOX). Small Craft Advisory in effect until 9 AM PDT Friday for zones 670-673. (See LAXMWWLOX). Small Craft Advisory in effect from 3 PM this afternoon to 9 AM PDT Friday for zone 676. (See LAXMWWLOX).
