10/1231 PM.
Temperatures away from the coast will warm into the 80s and 90s through Monday. 100 degree readings may occur locally in the warmest valleys and Antelope Valley. Coastal low clouds will develop each night, expanding into the valleys Tuesday as a cooling trend begins.
(tdy-Tue), 10/723 PM.
Overall, no major changes to previous forecast thinking in the short term period. Upper level ridge will peak in strength on Monday then move eastward on Tuesday/Wednesday as an upper low approaches/moves across northern California. At the surface, moderate to strong onshore pressure gradients will continue.
Forecast-wise, main issue will be temperatures. With the ridge peaking in strength, temperatures on Monday will be very warm with highs in the mid 80s to around 100 away from the coast (10-20 degrees above normal), but will be noticeably cooler at the coast due to the continued marine influence. Based on current Heat Risk numbers, do not anticipate any need for Heat Advisories on Monday. For Tuesday and Wednesday, a cooling trend for all areas is expected with the continued onshore pressure gradients and lowering H5 heights/thicknesses.
As for clouds, marine layer clouds and fog will continue during the night/morning hours. With the upper ridge peaking in strength tonight/Monday, stratus fog should remain confined to the coastal plain and lower coastal valleys. However for Tuesday and Wednesday, the stratus/fog will become more widespread and penetrate further inland as the inversion deepens in response to the lowering H5 heights. Each afternoon, some beach areas could remain cloudy due to the moderate to strong onshore flow. Other than the marine layer clouds, skies are generally remain mostly clear through the period.
As for winds, the moderate to strong onshore pressure gradients will generate gusty southwesterly winds across interior sections each afternoon and evening. At this time, any advisory-level winds are expected to remain rather localized (mainly across some of the Antelope Valley foothills).
(Wed-Sat), 10/121 PM.
Increasing northerly flow aloft is expected Thursday as the upper low over northern California moves into Nevada. Ensemble pressure gradient charts show increasing north to south gradients across the Santa Ynez Range and the western Transverse Range beginning as early as Wednesday evening and continuing through at least Saturday. Gradients expected to be in the -3 to -5 range during that period that would support at least advisory level winds, strongest in the late afternoon and overnight hours.
The increase in northerly flow may keep low clouds away from southern Santa Barbara County but otherwise expecting the marine layer to push into most of the coastal and valleys each day. Temperatures will be 5-10 degrees below normal Thursday, then reaching near normal temperatures Friday and 3-6 degrees above normal next weekend as high pressure aloft returns.
11/0120z.
At 0051Z at KLAX, the marine layer was 1000 feet deep. The top of the inversion was at 4800 feet with a temperature of 23 C.
High confidence in KWJF and KPMD TAFs.
Low to moderate confidence in remainder of TAFs. Timing of flight category changes may be off by 3 hours and one flight category at any point. There is a 30-40 percent chance that VFR conds prevail for KBUR/KVNY. There is a 40% chance of VLIFR conditions at KPRB in the 13Z-17Z time frame.
KLAX, Low to moderate confidence in TAF. Timing of flight cats may be off by +/- 3 hours, and there is a 25% chance of no VFR transition once cigs arrive. No significant easterly wind component is expected.
KBUR, Low to moderate confidence in TAF. There is a 30 percent chance that VFR conds prevail.
10/721 PM.
Across the outer and northern waters, Both winds and seas will diminish below Small Craft Advisory levels overnight. Conditions are then expected to remain below advisory levels across all the coastal waters through Tuesday.
Wednesday night through the weekend, winds and seas will start to strengthen/build, with SCA winds across the outer waters starting late Wednesday night and Seas reaching steep and choppy SCA levels around Friday night. There is a 30-40% chance of SCA winds across the inner waters, with the highest chances each afternoon and evenings especially across the western portion of the Santa Barbara Channel. GALE Force winds will be possible across the outer waters as early as Thursday afternoon, with highest chances on Saturday into Sunday.
Dense fog may become more widespread each night to morning through Tuesday morning.
Ca, NONE. PZ, Small Craft Advisory in effect until 9 PM PDT this evening for zone 645. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PDT Monday for zones 670-673. (See LAXMWWLOX).
