25/222 AM.
Very hot conditions will dominate the week, with a high risk for heat illness. Patchy night through morning low clouds and locally dense fog will be confined to some coastal areas. Significant cooling is likely over the weekend but it will remain warm.
(tdy-Thu), 25/223 AM.
The next three days will be the peak of the heat event. A large and very warm upper high will sit atop of NM/AZ and will bring 593-594 dam hgts to the area. Onshore gradients will be weak and even offshore from the north in the mornings. The marine layer will be shallow and will not xtnd very far inland. Marine layer stratus will most likely to affect the Central Coast where some dense fog is possible due to the shallowness of the marine layer. There are, however, some signals that an eddy will develop in which case there will be more low clouds south of Pt Conception.
Max temps will range from 100 to 106 degrees all three days across the vlys, lower mtns elevations and far interior. The western San Fernando Vly will be warmer still with max temps from 106 to 112 degrees. The lack of a strong onshore gradient in the afternoon will allow the inland areas of the cstl regions to warm into the 90s with even some 100 to 101 degree readings possible. In addition the the day time highs running 10 to 15 degrees above normal the overnight low will also be 6 to 12 degrees above normal as subsidence from the upper high sets up a strong and hot inversion right at vly/foothill elevations. On Wednesday a the usual onshore push across the Central Coast will disappear and max temps there will rise 8 to 12 degrees with many locations reaching into the 90s.
Almost all of the area is blanketed by Extreme Heat Warnings and Advisories. Please see the product LAXNPWLOX for all details. Residents need to take precautions to avoid heat related dangers when outside.
Sundowner winds will affect southern Santa Barbara County through the week, and should increase some each night. Wind Advisories might be needed tonight and/or Wednesday Night.
(Fri-Mon), 25/223 AM.
A substantial trof will move into the west coast and push the upper high to the south. The flow will slowly switch to the SW during the period and hgts will fall to 588 dam. Some offshore flow may persist in the morning esp from the north, but the afternoon onshore push to the east will increase.
Most max temps will fall 1 to 2 degrees on Friday (except for the Central Coast where better onshore flow will bring 3 to 6 degrees of cooling). This small amount of cooling will not be enough to eliminate the heat risk and all warnings and advisories will continue. Look for 5 to 10 degrees of cooling across the csts/vly on Saturday as the trof and onshore flow really begin to affect the weather (the mtns and far interior will see 2 to 4 degrees of cooling). On Sunday all areas will cool 3 to 6 degrees and this will bring many areas to or even below normal max temps. 2 to 4 additional degrees of cooling is likely next Monday and this will reduce coastal max temps to the 70s (upper 60s/lower 70s Central Coast) and in the mid 80s to mid 90s for the vlys.
25/0922z.
At 0830Z at KLAX, the marine layer was 500 feet deep. The top of the inversion was 2000 feet and 31 C.
High confidence in VFR conditions through at least Tuesday KPRB, KSBA, KBUR, KVNY, KPMD, and KWJF.
For KSBP and KSMX, timing of flight category changes could be +/- 2 hours of current forecast.
Chances of LIFR/IFR ceilings tonight at KOXR (20%) KCMA (20%) KSMO (25%) KLAX (25%) KLGB (25%).
KLAX, Moderate confidence in TAF with a 25 percent chc of 3SM BKN005 conds 12Z-16Z. No significant easterly wind component is expected.
KBUR, High confidence in CAVU TAF.
25/223 AM.
For the Outer Waters, high confidence in current forecast. This afternoon through Saturday, SCA level winds are expected across all of the Outer Waters. Seas will remain at SCA levels, initially due to short period combined seas, but approaching 8 to 10 feet by Thursday.
For the Inner Waters north of Point Sal, moderate to high confidence in current forecast. Late this afternoon through late tonight there is a 40-60% chance of SCA winds. For Wednesday through Saturday, there is a 60-80% chance of SCA level winds in the afternoon and evening hours. Short period seas will be common throughout the week, especially during the afternoon to evening.
For the Inner Waters south of Point Conception, moderate to high confidence in current forecast. For a majority of the southern Inner Waters, high confidence in winds and seas remaining below SCA levels through Saturday. The only exception will be the western half of the Santa Barbara Channel where there is a 60-80% chance of SCA level winds through Saturday in the late afternoon and evening hours.
Ca, Heat Advisory in effect until 10 AM PDT this morning for zones 38-87-88-349>358-362-366>376-378>380-548. (See LAXNPWLOX). Extreme Heat Warning in effect from 10 AM this morning to 8 PM PDT Friday for zones 38-87-88-349>358-362-366>376-378>383-548. (See LAXNPWLOX). Heat Advisory in effect from 10 AM Wednesday to 8 PM PDT Thursday for zones 341-347-348. (See LAXNPWLOX). Heat Advisory in effect from 10 AM this morning to 8 PM PDT Friday for zones 342>345. (See LAXNPWLOX). Red Flag Warning in effect from 10 AM this morning to 3 PM PDT Friday for zones 345-353-375>380. (See LAXRFWLOX). PZ, Small Craft Advisory in effect from 3 PM this afternoon to 3 AM PDT Wednesday for zone 645. (See LAXMWWLOX). Small Craft Advisory in effect from 3 PM this afternoon to 3 AM PDT Thursday for zone 670. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PDT Thursday for zones 673-676. (See LAXMWWLOX).
