15/1240 AM.
Night through morning marine layer clouds will continue for the coast and valleys, shrinking in coverage each day into next week. Cooler than normal temperatures continue through this weekend, then warmer than normal temperatures return next week, with widespread moderate Heat Risk.
(tdy-Mon), 15/105 AM.
The main story over the next seven days is the warming trend continuing into next week. While the weak trough along the coast remains in place, the large area of high pressure will continue to expand west, nudging in higher 500 mb heights each day. Come Monday we will solidly be under the influence of the upper level ridging as the trough is moved west well off the coast. Onshore flow will weaken simultaneously, leading to a gradual warming trend into Monday. While high temperatures across most of the area will remain cooler than mid August normals through the weekend, many areas will be at or above normal by early next week.
Marine layer stratus is expected to be present through the period, shrinking in coverage each day and likely receding to just the coastal areas by Monday. The absence of marine layer clouds will allow for quicker warming away from the coastal areas, much different than what we saw the last couple of days.
An increase in northwest to northerly winds is likely as soon as Sunday as the north-south pressure gradient strengthens. We will see increasing gusty winds over southwest Santa Barbara County and interior mountains (especially through the Grapevine) and the Antelope Valley. At this point winds aren't expected to be widespread advisory levels, however, there is a moderate chance for advisory level winds across southwest Santa Barbara County on Monday.
(Tue-Fri), 15/105 AM.
There is now good agreement amongst models that the upper level ridging will remain over the Western US, bringing hot and dry conditions to Southwest California through at least Thursday. There is a bit more disagreement regarding the evolutions of the upper pattern starting Friday. Cluster analysis shows fairly equal probabilities between ridging slightly weakening, yet continuing across the West and a weak troughing pattern setting up along the West Coast, nudging the ridge back towards the east. The latter solution does keep the main axis of the trough slightly north and west of us, so warm and dry conditions would still be likely if this solution comes to fruition, just not as warm as the other scenario.
Regardless of how the pattern plays out at the end of the week, the upper level ridging will bring hot and dry conditions to the region Tuesday through at least Thursday. Largest increases in temperatures will be most notable away from the immediate coasts as marine layer influences will remain confined to the coastal areas. High temperatures will revert back to what has seemingly been the case much of this summer: warmer than seasonal normals. Expanding moderate Heat Risk will become common Tuesday through at least Thursday, bringing a moderate chance of Heat Advisories to many areas.
The marine layer is expected to be fairly shallow,thus dense fog may become an issue in some areas. Marine layer coverage may be wiped out across the Santa Barbara south coast and potentially Ventura County as the increasing north-south pressure gradient will allow for weak to potentially moderate Sundowner winds. Aside from gusty winds across southwest Santa Barbara County, interior mountains and desert will likely see an uptick in northwest to north winds overnight. Advisory level winds are not expected, aside from a low to moderate chance over southwestern Santa Barbara County.
15/1127z.
At 0836Z at KLAX, the marine layer was at 2300 feet deep. The top of the inversion was near 3500 feet with a temperature of 20 C.
High confidence in VFR TAFs for KPMD & KWJF.
Moderate confidence in remaining TAFs. Patchy marine layer will result in SCT to OVC 015 conds at KSBA, KOXR, KCMA through the morning. VFR transitions may be off +/- 2 hours. Arrival tonight may be off +/- 4 hours, lowest confidence KSBA, KOXR, KCMA. Low chance for brief IFR cigs at KSBP/KSMX. No significant wind issues expected.
KLAX, Moderate confidence in TAF. Arrival and clearing of MVFR CIGs may be off +/- 2 hours of current forecast, then arrival time Saturday night may be between 03Z-10Z with slightly lower ceilings, but still expected MVFR conds. No significant east wind component expected.
KBUR, Moderate confidence in TAF. VFR transition may be any time from 16Z-18Z. Arrival tonight may be off +/- 4 hours from forecast.
14/806 PM.
High confidence that conditions will remain below Small Craft Advisory (SCA) criteria across the coastal waters through Saturday morning. There is a 40-60 percent chance of SCA winds developing over the outer waters from near Point Conception southward to San Nicolas Island and in the vicinity of the Channel Islands. Further north over PZZ670 there is a 30-40 percent chance of SCA gusts from late Saturday afternoon through late Saturday night.
There is a better chance of SCA winds developing Sunday afternoon from near Point Conception and southward over the outer waters, and over the nearshore waters inside the S CA Bight. These nearshore winds are likely to subside early Monday morning, but with SCA winds continuing over the two southern outer zones PZZ673-676. By Monday late afternoon or evening, SCA winds are likely to expand northward to the outer and nearshore waters north of Pt. Sal, and into the Santa Barbara Channel. Local gusts to 25 knots may affect portions of PZZ655 Monday evening.
Strong SCA winds are likely to persist over the outer waters Tuesday and Wednesday, affecting the nearshore areas in the afternoon and evening hours. Local gale force gusts will be possible during this time. In addition, building short period seas are expected, likely rising to around 8 feet over the outer waters.
Ca, NONE. PZ, Small Craft Advisory in effect from 3 PM this afternoon to 3 AM PDT Sunday for zones 673-676. (See LAXMWWLOX).
