17/201 PM.
Well above normal temperatures will continue away from the coast through Friday. Unsettled weather is possible this weekend along the Central Coast, spreading to all areas with a potentially significant storm near the middle part of next week.
(tdy-Sun), 18/236 PM.
Low clouds and fog in some coastal areas was beginning to burn off or push offshore this morning. Breezy northerly winds across the mountains and foothills continued to be generally below advisory levels. Added some partly cloudy wording to forecast as high clouds have filled into the region more than anticipated.
Our focus continues to be on the period of unsettled weather next week, especially Tuesday through Thursday or Friday. We'll take a closer look at the details today - but a quick look this morning indicates that active weather may stick around for a couple of days beyond the atmospheric river event (late Tuesday through early Thursday) or potentially into next weekend.
Stay tuned to the weather, especially for those traveling or planning outdoor activities this holiday season.
On Friday the ridge will be pushed to the south and flat westerly flow sets up over the area. Hgts will fall to about 585 dam (still well above normal). Low clouds will be similar to Wednesday and pretty much confined to the Long Beach area. Much weaker offshore flow at the sfc will lead to 3 to 6 degrees of cooling across the csts/vlys. The lack of cool air advection from the San Joaquin Vly will lead to 2 to 4 degrees of warming across the interior.
Flat westerly flow continues over the area on Saturday. Hgts will dip down to 582 dam. Onshore flow to the east will increase from 1 mb in the morning to about 3 mb in the afternoon, the offshore flow from the north will be 3 mb weaker in the afternoon compared to Friday. The onshore flow and falling hgts will bring some coastal low clouds to the area in the morning. At the same time the southern edge of an atmospheric river (AR) affecting the northern portion of the state will move south enough to south to bring mostly cloudy skies to most over the area save for LA County which will end up partly cloudy. The AR could (20 percent chc) bring some light rain to SLO county. The cooling trend will continue as falling hgts and better onshore flow combine to lower most temps 3 to 6 degrees. The Central Coast will be the exception with little change in temps. Max temps, however, will remain above normal (3 to 6 degrees csts, 5 to 10 degrees vlys and 10 to 15 degrees mtns and far interior).
(Mon-Thu), 18/201 PM.
Tuesday remains the day of transition. The AR will sag south and the flow will become even more southwesterly. Rain chances will overspread the entire area. Rain chances have increased with the latest forecast and now sit around 40 percent for LA county, 50 percent for VTA county, 50 to 60 percent for SBA county and 60 to 70 percent for SLO county. The forecast rainfall amounts have also been increased. SBA and SLO counties will now likely see a half inch to an inch of rain, while a quarter inch to a half inch is possible for VTA and LA counties.
There has been a slight change in the current thinking for the Wed/Thu storm. Both the EC and esp the GFS (as well as most ensembles and the AI enhanced mdls) are now speeding up the system (hence the wetter Tuesday fcst). This forecast (Which very well might change since it is 7 to 8 days away) now call for the bulk of the rain to fall Wednesday through Thursday (Christmas) morning. Very preliminary (and subject to change) rainfall totals for the Wed/Thu time period call for 2 to 4 inches of rain csts/vlys, 4 to 6 inches across the mtns and 1 to 2 inches for the interior sections. It is too early to get a handle on rainfall rate predictions. Snow levels will be over 8000 ft but will start to fall later Thursday.
Model agreement falls off pretty rapidly after Thursday, but there is a potential for another system over the weekend of the 27th and 28th.
18/2214z.
At 2200Z at KLAX, the marine layer depth was around 400 feet. The top of the inversion was 2000 feet with a temperature of 25 degrees Celsius.
For the 00Z TAF package, high confidence in KSBP, KSBA, KOXR, KCMA KBUR, KVNY, KPMD and KWJF.
For KSMX, KLAX, KLGB and KLGB, moderate confidence in 00Z TAFs as timing of flight category changes with marine layer could be +/- 3 hours of current forecasts.
KLAX, Overall, moderate confidence in 00Z TAF. Timing of flight category changes could be +/- 3 hours of current forecasts. No significant easterly wind component is expected.
KBUR, High confidence in 00Z TAF.
18/1150 AM.
For the Outer Waters, moderate to high confidence in current forecast. Today through Friday evening, Small Craft Advisory (SCA) level winds will continue across all of the Outer Waters. For Friday night and Saturday, the SCA level winds will continue across PZZ673/676. Additionally, there will be 20% chance of Gale force wind gusts around Point Conception today through Saturday. For Sunday through Monday, winds and seas will remain below SCA levels for all of the Outer Waters. For Tuesday, there is a 60-80% chance of SCA level southeasterly winds.
For the Inner Waters north of Point Sal, moderate to high confidence in current forecast. Today through Friday, there is a 60-80% chance of SCA level winds in the afternoon and evening hours. For Saturday through Monday, high confidence in winds and seas remaining below SCA levels. For Tuesday, there is a 40-50% chance of SCA level southeasterly winds.
For the Inner Waters south of Point Conception, moderate to high confidence in current forecast. Today through Friday, there is a 60-70% chance of SCA level northwest winds across the western half of the Santa Barbara Channel, mainly during the late afternoon and evening hours. Otherwise, high confidence in winds and seas remaining below SCA for the southern Inner Waters today through Monday. On Tuesday, there is a 30-50% chance of SCA level southeasterly winds.
Ca, NONE. PZ, Small Craft Advisory in effect until 9 PM PST this evening for zone 645. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PST Friday for zone 650. (See LAXMWWLOX). Small Craft Advisory in effect until 9 PM PST Friday for zone 670. (See LAXMWWLOX). Small Craft Advisory in effect until 9 AM PST Saturday for zones 673-676. (See LAXMWWLOX).
