20/306 AM.
Night through morning marine layer clouds will be confined to the coastal areas, mostly north of Pt Conception, through much of this week. Warm conditions are expected away from the immediate coast slight cooling is forecast Friday through the weekend.
(tdy-Sat), 20/723 AM.
***UPDATE***
Latest satellite and surface observations indicate generally clear skies across the area except for some Central Coast stratus/fog and some patchy stratus/fog south of Point Conception. Current sounding data indicates marine inversion around 1000 feet in depth. No significant winds are observed.
Forecast-wise for the immediate short term, no issues are expected. Heat will be the main concern today. Morning TEMP STUDY data indicates a day very similar to Wednesday with respect to high temperatures. So, widespread moderate heat risk can be expected and current collection of HEAT ADVISORIES for interior sections still look very much on track.
Current marine layer stratus/fog will dissipate by the afternoon with mostly sunny skies expected for all areas. No significant winds are expected this afternoon. However, there will be another round of locally gusty Sundowner winds this evening across the western half of the Santa Ynez Range (the usual Gaviota and Refugio areas).
Overall, current forecast has good handle on the immediate short term. So, no significant updates are expected.
***From Previous Discussion***
Another hot day on tap today. Low clouds will be mostly confined to the Central Coast with only patchy coastal low clouds occuring south of Pt Conception. 595 dam hgts, weak onshore flow and a limited marine layer will allow max temps to reach 95 to 105 degrees in the vlys, lower mtn elevations and the far interior where heat advisories are in effect. Less hazardous but still above normal temps will occur across the rest of the area.
A little change in fcst for tonight. A weak disturbance will rotate over LA county later in the evening and overnight. All hi rez convection allowing mdls show this disturbance generating some convection as it passes overhead. Have added a 15 to 20 percent chc of showers and TSTMs to the LA county overnight forecast.
Onshore flow will continue to bring low clouds to the Central Coast. Less confidence on the extent of the morning low clouds south of Pt Conception as the overnight disturbance may prevent their formation. Better onshore flow, slightly lower hgts and increased mid and high level clouds from the SE monsoon flow aloft will all conspire to lower max temps a few degrees. Humidities may rise a little so it might not feel much better. None of the convection allowing mdls show any development in the afternoon, but given the flow pattern and increasing mid level moisture the current 10-15 percent chc of convection over the eastern San Gabriel's and nrn VTA county mtns seems reasonable.
Clearer skies Friday night and increased onshore flow at the sfc should help more low clouds form south of Pt Conception Saturday morning. There will be decreased moisture at the mid levels so the chc of afternoon convection over the mtns is lower (5 to 10 percent chc). The sunnier skies in the afternoon will likely bring 1 or 2 degrees of warming to most areas.
There will be no wind issues during the 3 day period, just the typical locally gusty northerly winds across the western Santa Ynez range.
(Sun-Wed), 20/306 AM.
Pretty benign weather is forecast for the xtnd period. Srn CA will be sandwiched between SW flow to the northwest and SSE to the SE. The current forecast shows only minor day to day variations in temperatures. Max temps will mostly run 2 to 4 degrees above normal. The one caveat is that the EC bring neutral flow in the E/W direction and actual offshore flow from the north during the Tue/Wed period. If this develops max temps will come in much warmer than currently fcst for some areas.
The morning low cloud pattern will be similar to the short term with good confidence that the Central Coast will see plenty of morning low clouds. Lower confidence for areas south of Pt Conception with low cloud development pretty dependent on whether an eddy spins up or not.
The area will be on the fringe of the monsoon transport through the period. It is most likely the the convection will stay to the south and east of LA county with only a 5 to 10 percent chc of it reaching LA county on any given afternoon.
20/1730z.
At 1615Z at KLAX, the weak marine layer was 1200 feet deep. The top of the inversion was at 2900 feet with a temperature of 28 C.
High confidence in VFR TAFs for KPMD, KWJF, KBUR, and KVNY.
Good confidence in TAF for KPRB with a 15% chance for LIFR conds after 10Z.
Good confidence in TAF for KSBP and KSMX as timing of flight cat changes may be off +/- 2 hours of forecast. Cig height may be off +/- 200 feet.
Moderate confidence in TAF for KOXR and KCMA as timing of flight cat changes may be off +/- 3 hours. 30% chance for no low clouds.
Low confidence in TAFs for KSBA, KLAX, KLGB, and KSMO, with a 40-50% chance for VFR conds to prevail, highest at KSBA/KSMO. Timing of arrival of cigs may be off +/- 3 hours.
All LA/Ventura county sites have a 15-20% chance of SHRA/TSTM from 03Z-15Z.
KLAX, Low confidence in TAF after 21/05Z with good confidence before. There is a 40% chance of no low clouds. Timing of arrival of cigs may be off +/- 3 hours. 20% chance for cigs 003-004. 15-20% chance of SHRA/TSTM from 03Z-15Z. Any east wind component is expected to remain below 8 kt.
KBUR, High confidence in CAVU TAF. No wind issues expected.
20/730 AM.
Moderate to high confidence in periods of Small Craft Advisory (SCA) level winds (20-30 knots) across the Outer Waters each afternoon and evening into next week, thus a long duration SCA has been issued through Sunday morning. This may need to be extended into next week as we progress through the weekend. Local gusts of 20-25 kt will be possible across the nearshore waters along the Central Coast today, then there is a moderate chance for more widespread wind gusts reaching 25 knots starting Friday.
Aside from gusts of 20-25 knots reaching the western half of the Santa Barbara Channel each afternoon/evening starting Friday, widespread SCA conditions are not likely across the nearshore waters south of Point Conception. Localized gusts near 20 knots are possible near Point Dume and the San Pedro Channel during the afternoon through early evening hours starting Friday.
Ca, Heat Advisory in effect until 8 PM PDT this evening for zones 38-88-343>345-351-353-371>373-375-376-379-380-548. (See LAXNPWLOX). PZ, Small Craft Advisory in effect from 3 PM this afternoon to 9 AM PDT Sunday for zones 670-676. (See LAXMWWLOX). Small Craft Advisory in effect until 9 AM PDT Sunday for zone 673. (See LAXMWWLOX).
