23/851 AM.
High pressure anchored over the West will keep a hot air mass in place through early next week. The hottest temperatures are expected for late this weekend and through the weekend. Elevated risk for heat stress and heat illness will continue as the prolonged hot daytime and warm overnight conditions are expected through Monday. Gusty northerly winds will continue affect portions of the area through Friday.
(tdy-Sat), 23/840 AM.
An upper-level ridge of high pressure remains anchored over the Western States this morning. Southwest flow aloft is waning and the surface pressure gradients are responding to the ridge aloft start to build over the region. Onshore pressure gradients continue to weaken this morning, but onshore flow will remain in place over the coming days, albeit weaker than the last several days. The marine layer depth thin over the coming days as 500 mb heights rise over the region.
With heights climbing and onshore flow weakening, a warming trend will develop over the coming days. Most areas will likely see the peak temperatures of this heat wave over the next several days. Areas north of Point Conception are starting about 3-6 degrees cooler than yesterday, but the air mass will catch up as onshore pressure gradients are weakening this morning. For areas south of Point Conception, temperatures are running about 4 to 7 degrees above yesterday's values currently. Heat advisories remains in effect over most interior coastal, valley, and mountain areas, while an extreme heat warning remain in effect across the Antelope Valley floor. An expansion of the heat advisory is being considered across the interior Central Coast over the next couple of days. With temperatures starting out cooler along the Central Coast, temperature will likely not get warm enough for advisory criteria today, but a daytime hour heat advisory could be needed for the daytime hours on Friday and Saturday when temperatures soar into the upper 80s and lower 90s in some locations.
Gusty Sundowner winds will develop across southern Santa Barbara County again this afternoon and evening. Last evening, Santa Barbara Airport peaked at 95 degrees as breezy Sundowner winds arrived. A wind advisory will be issued here shortly for late this afternoon and tonight.
***From Previous Discussion***
The temperatures will be compounded by the greater than normal humidity resulting from the warmer than normal sea sfc temps and weak monsoon flow. The higher humidity and powerful inversion created by the subsidence from the upper high will also bring much higher than normal overnight lows each night.
The combination of above normal daytime highs and overnight lows along with the higher humidities will create a dangerous environment as people's bodies (those without AC) will be heat stressed day and night with no real recovery period. For all of these reasons heat advisories are in effect through Monday evening. Please see the product LAXNPWLOX for all of the details.
There will be a few areas and times within the Advisory Area that will meet warning criteria, but the long-duration Advisory make for a less complicated and easier to understand message. The risk for heat illness is high, especially for sensitive groups like the very young, the very old, those without air conditioning, and those active outdoors.
The offshore push from the north will likely keep the low clouds away from the beaches south of Pt Conception, but the onshore flow to the east will bring the typical night through morning low clouds and fog to the Central Coast.
The offshore push from the north will bring gusty winds to southern Santa Barbara County, the I-5 Corridor, and the western Antelope Valley this afternoon and evening as well as Friday Night afternoon and evening. The SBA south coast will likely need another wind advisory tonight and possibly again Friday night.
The upper high's position over the 4 corners will put it in a position for some monsoon flow leading to afternoon mtn convection. At this time it looks like the chc is less than 10 percent, but it is not zero.
(Sun-Wed), 23/308 AM.
The upper high will begin to move back east on Sunday. More importantly there will be an increase in the onshore flow and possible return of some morning low clouds across the csts. The low but non-zero threat of monsoon convection will remain over the mtns. Max temps will drop a few degrees but advisory level heat will continue.
Hgts fall some on Monday as the upper high continues to move to the east. Onshore flow continues to increase. This will bring a few more degree of cooling. There may be enough cooling to consider dropping a few areas from the heat advisories, but for now its prudent to leave them all in through Monday evening.
More cooling on Tuesday should be enough to eliminate the heat threat. By next Wednesday highs will still be above normal but only by 3 to 5 degrees.
Mdls remain consistent showing another round of heat developing at the end of next week.
23/1810z.
At 1701Z at KLAX, the marine layer was 1300 ft deep. The top of the inversion was at 4600 ft with a max temperature of 28 C.
High confidence in VFR TAFs for KPMD, KWJF, KBUR, & KVNY.
Moderate confidence in TAFs for KSMX and KSBP. VFR transition could be off by 1 hour.
Fair confidence in the remainder of the TAFs with a 25 percent chc of IFR/LIFR conds 12Z-16Z.
KLAX, Fair confidence in TAF. There is a 25% chance of OVC004 conds 12Z-16Z. No significant east wind component expected.
KBUR, High confidence in TAF.
23/752 AM.
Widespread Small Craft Advisory (SCA) NW winds will likely continue through the weekend across the Outer Waters, with seas nearing 10 ft at times. Gale Force wind gusts will impact the outer waters this afternoon through late night, and there is a 30% chance of winds restrengthening to Gale Force levels each day across the outer waters north of the Channel Islands through Sunday. SCA winds will spread into the nearshore waters along the Central Coast and Santa Barbara Channel at times through the forecast period.
23/1020 AM.
A long period, southern hemisphere swell will arrive later this week and will add to the continuing swell from Hurricane Fausto. This swell will result in an increased risk of dangerous rip currents across the coastal beaches, as well as elevated surf of 3-6 ft across the Los Angeles and Ventura County Beaches. Therefore, Beach Hazard Statements are in effect through the weekend for Los Angeles and Ventura County beaches and the Central Coast beaches. Rip currents and elevated surf will be strongest across south to southwest facing beaches and harbors such as Avila Beach.
The Eastern Pacific looks to remain active with tropical systems over the next couple of weeks. This could result in additional southerly swells to impact the coastline.
Ca, Heat Advisory remains in effect until 8 PM PDT Monday for zones 38-88-342>345-348>358-362-366>382-548. (See LAXNPWLOX). Beach Hazards Statement in effect from Friday afternoon through Sunday evening for zones 340-346. (See LAXCFWLOX). Wind Advisory in effect from 3 PM this afternoon to 3 AM PDT Friday for zones 349-351. (See LAXNPWLOX). Beach Hazards Statement in effect through Sunday evening for zones 354-362-366. (See LAXCFWLOX). Extreme Heat Warning in effect until 8 PM PDT Monday for zone 383. (See LAXNPWLOX). PZ, Small Craft Advisory in effect until 3 AM PDT Saturday for zone 645. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PDT Friday for zone 650. (See LAXMWWLOX). Small Craft Advisory in effect from 3 PM this afternoon to 9 PM PDT this evening for zone 655. (See LAXMWWLOX). Small Craft Advisory in effect until noon PDT today for zones 670-673-676. (See LAXMWWLOX). Gale Warning in effect until 3 AM PDT Friday for zones 670-673-676. (See LAXMWWLOX). Small Craft Advisory in effect from 3 AM Friday to 3 AM PDT Saturday for zones 670-673-676. (See LAXMWWLOX).
