17/654 AM.
Night through morning marine layer clouds will be confined to the coastal areas through much of this week. Warmer and drier conditions are expected away from the immediate coast, with peak heat likely being Tuesday through Thursday when moderate heat risk is expected in warmest locations.
(tdy-Wed), 17/953 AM.
***UPDATE***
No changes in the forecast for the morning update. Widespread warming by a few degrees is still on track for today. Main focus on the forecast will be looking at if there is a need for extending the heat advisories to include inland coastal areas for Ventura and L.A. Counties.
***From Previous Discussion***
Over the next three days a very large and hot upper high, currently centered over TX, will shift to the west and end up over AZ. Hgts will no change much and will sit near 594 dam through the period. The sfc gradients will not exhibit much change either. The N/S gradient will be near neutral in the morning and weakly onshore in the afternoon. The W/E gradient will be weakly onshore in the morning and moderately onshore in the afternoons.
Marine layer clouds will be confined to the coastal sections. Good confidence that the Central Coast will have the low clouds each morning. Less confidence for the csts south of Pt Conception where beaches could be clear on any given morning.
The high pressure, hier than normal hgts and weaker than normal onshore flow will bring another round of heat to Srn CA. Most areas will see 2 to 4 degrees of warming today although some vly areas will see up to 6 degrees. This warming will bring warmer than normal temps to all areas save for the Central Coast which will end up 2 or 3 degrees blo normal. Another 2 to 4 degrees of warming (locally 6 degrees across the Central Coast) Tuesday will bring above normal max temps to all areas. Most areas will see 1 or 2 degrees of additional warming on Wednesday. The strong inversion, much warmer than normal sea sfc temps and the warm atmosphere will also bring warmer than normal overnight low temps to much of the area. Most cst/vly locations will only have lows in the upper 60s to lower 70s.
The combination of warmer than normal highs and lows will bring significant heat risk to many areas. HEat advisories were issued Sunday for the San Fernando, San Gabriel, and Santa Clarita Valleys as well as the lower mtn elevations. There is a 40 percent chance the downtown LA area, the VTA county vlys, and the Santa Monica mtns will also need heat advisories starting Wednesday. Please see the product LAXNPWLOX for all of the details.
Gusty north winds will affect southwest Santa Barbara County and the I-5 corridor near the Grapevine each evening and overnight. While most of these winds are expected to remain below advisory levels, there is a chance for advisory level winds in the Gaviota to San Marcos Pass area.
(Thu-Sun), 17/245 AM.
Thursday will greatly resemble Wednesday as there will be little change in any of the synoptic parameters. The only change will be some cooling across the Central Coast as that area will have a stronger sea breeze.
There will be a little bit of cooling on Friday mostly due to an increase in mid and high level clouds. Still max temps will remain well above normal. The upper high is forecast to migrate to the four corners area which will set up SE monsoon flow over Srn CA. PWs approach 1.5" across Srn LA county. This influx of moisture will allow for a non zero chc of showers or TSTMs to develop over the mtns and Antelope Vly.
The upper high will be nudged to the east for the weekend as a weak trof moves through the PACNW and the northern half of the state. The weak lift from the trof may bring a little better low cloud development although this is far from certain. Look for 1 to 2 degrees of cooling each day - maybe a little more for SLO county due to the proximity to the trof. The cooling will bring most areas north of Pt Conception down to near or below normal temps. South of Pt Conception, however, most max temps will remain a few degrees above normal.
17/1645z.
At 1630Z at KLAX, the marine layer was 900 feet deep. The top of the inversion was 3100 feet with a temperature of 24 degrees Celsius.
For 18Z TAF package, high confidence in KBUR, KVNY, KPMD and KWJF.
For all other sites, moderate confidence in 18Z TAFs. Forecast timing of return of CIG/VSBY restrictions could be +/- 2 hours of current forecasts. Other sites that are VFR have a 30-40% chance of getting CIG/VSBY restrictions 08Z-17Z.
KLAX, Moderate confidence in 18Z TAF. There is a 40% chance of IFR conditions 08Z-17Z. No significant easterly wind component is expected.
KBUR, High confidence in 18Z TAF with VFR conditions expected through the period.
17/705 AM.
For the Outer Waters, high confidence in current forecast. Today through Friday, Small Craft Advisory (SCA) level winds can be expected. Building short-period seas can be expected across the Outer Waters, rising to the 7-9 foot range.
For the Inner Waters north of Point Sal, moderate to high confidence in current forecast. For today, there is a 30% chance of SCA level winds in the afternoon and evening hours. For Tuesday through Friday, there is a 60-80% chance of SCA level winds in the afternoon and evening hours.
For the Inner Waters south of Point Conception, moderate to high confidence in current forecast. For the western half of the Santa Barbara Channel, there is a 60-80% chance of SCA level winds today through Friday, mainly in the late afternoon and evening hours. Elsewhere south of Point Conception, high confidence in winds and seas remaining below SCA levels today through Friday.
Ca, Heat Advisory in effect from 10 AM Tuesday to 8 PM PDT Thursday for zones 38-88-343>345-351-353-371>373-375-376-379-380-548. (See LAXNPWLOX). PZ, Small Craft Advisory in effect until 3 AM PDT Tuesday for zone 650. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PDT Wednesday for zones 673-676. (See LAXMWWLOX).
