28/228 AM.
Hotter than normal conditions will continue for the foreseeable future. Slight cooling will take place through Thursday, with heat increasing again Friday through Sunday. The hot and humid conditions during the day and night will bring elevated risks of heat-related illness.
(tdy-Thu), 28/853 AM.
***UPDATE***
The issuance of heat headlines for late this week and into this weekend will be forthcoming within the next couple of hours.
Otherwise, the forecast is well on-track, and no changes have been made to the ongoing forecast.
***From Previous Discussion***
Widespread MODERATE TO HIGH heat risk is very likely to return Friday. Please see the extended discussion below for weather details.
Fairly quiet conditions expected through the short term. A very weak trof will be over the state today and most of Wednesday. Hgts, however will only drop to 590 dam. Later Wednesday and into Thursday, a strong upper high currently centered over NM will begin to migrate westward. By Thursday afternoon it will be over the 4 corners regions and hgts over Srn CA will rise to 596 dam.
Surface pressure gradients will be mdt-stg onshore to the east (strongest in the late afternoon). The N/S gradient will vary from weak offshore in the morning to weak onshore in the afternoon.
The morning low cloud pattern will be fairly similar each day. Low clouds are likely each morning across the LA coast and portions of the Central Coast. Low clouds may also form over the csts of SLO and VTA counties, but there is only about a 50 percent chc each day.
The trof's influence will bring 1 to 2 degrees of cooling each day today and Wednesday. Even with the cooling most of the high temps on Wednesday will be 2 to 4 degrees over normal with 80s across the csts, 90s in the vlys and 98-102 degrees across the lower mtn elevations and far interior. The upper highs influence will be felt on Thursday as max temps will bump up 1 to 3 degrees with the increasing hgts.
Gusty Sundowner winds will occur each evening and overnight across southwest Santa Barbara County. These winds will likely come in just under advisory levels.
A large south swell from Major Hurricane Genevieve will further enhance large wave and potentially deadly rip currents for some area beaches. See Beaches discussion below and associated coastal hazard products for details.
(Fri-Mon), 28/225 AM.
Widespread MODERATE TO HIGH heat risk is very likely to return Friday into the weekend. Now is the time to start socializing this threat with your community and family and consider rescheduling activities that might but you or your loved ones at risk. Have a plan to stay cool, especially if work or other activities take you outside mid-morning to mid-evening hours or do not have access to air conditioning.
The upper high will continue to track to the west on Friday and will peak Saturday afternoon as it settles over AZ with a central hgt of 600 dam. Hgts over Srn CA both Fri and Sat could reach 598 dam. For context since 1948 there have only been 12 days during the months of July and August where hgts have been 598 dam (10 days) or 599 dam (2 days). Hgts will fall some Sun and Mon as an impulse works its way through the north of the State.
Heat Advisories and warnings are a near certainty for the Friday to Sunday period. At this time there is high confidence in the forecast for widespread highs of 95-105 away from the coast with pockets of 105-115 in warmest coastal valleys to interior during the peak of the heatwave Friday and Saturday. Highs 80-95 will be common coastal areas away from the beaches. Overnight lows in the 70s and 80s for many areas will increase risk for heat stress through prolonged exposure and limited ability for dwellings without air conditioning to cool overnight.
Night to morning low clouds will diminish or disappear during this time, although weakened onshore focused to the east will somewhat limit the heat nearest the coast. However, well above normal water temperatures will continue to drive increased humidity near the coast, decreasing the body's ability to cool through sweating.
There is also an increased risk for large and dangerous fires due to the hot and unstable conditions with pockets of gusty winds, perhaps, especially southwest Santa Barbara County and the I-5 corridor in the mountains into the weekend.
28/0936z.
At 0836Z at KLAX, the marine layer was 900 ft deep. The top of the inversion was near 1800 ft with a temperature of 26 C.
High confidence in TAFs for KBUR, KVNY, KPMD, KWJF, and KPRB.
Moderate confidence in TAFs for KLGB, KLAX, KSMO, KSBP, and KSMX where the arrival and departure times of CIGs could be off by +/- 2 hours. Min CIG heights may be off by +/- 200 feet, with a 20% chance for VLIFR conds at KSMX/KSBP. There is a 30-40% chance cigs fail to reach KLGB, KLAX, and KSMO.
Moderate confidence in TAFs for KOXR and KCMA with a 30 percent chc of IFR/LIFR cig/vis 12Z-17Z.
KLAX, Moderate confidence in TAF. Cigs could arrive as late as 13Z. VFR conds could arrive as early as 15Z or as late as 17Z. High confidence in any east winds staying under 7 knots.
KBUR, High confidence in CAVU TAF.
28/803 AM.
For the Outer Waters, moderate to high confidence in current forecast. Today through Saturday, high confidence in a combination of Small Craft Advisory (SCA) level winds and seas. Additionally, there is a 20-30% chance of Gale force winds through this evening across PZZ670/673.
For the Inner Waters north of Point Sal, moderate to high confidence in current forecast. Today through Wednesday, high confidence in SCA level winds in the afternoon and evening hours. For Thursday through Saturday, there is a 40-50% 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 a majority of the southern Inner Waters, high confidence in winds and seas remaining below SCA levels through Saturday. The only exception will be the western half of the Santa Barbara Channel with a 20-30% chance of SCA level each day, during the late afternoon and evening hours.
Seas are expected to hover near 8-10 feet across the waters away from the coasts much of the week. A southerly swell from Hurricane Genevieve will continue across the coastal waters through this weekend. This south swell may impact south facing harbors, including Port San Luis.
28/802 AM.
An extended period of a combination of moderate to long period southerly swells will continue through this week and into next weekend. A long 17-20 second period SSW Southern Hemisphere swell will continue to impact our area through mid week, then will be enhanced by southerly swell from Category 5 Hurricane Genevieve, moving into the coastal waters today.
A Beach Hazards Statement is in effect through Wednesday (except through Saturday along the Central Coast) due to the increased risk of dangerous rip currents and elevated surf. There have been numerous ocean rescues reported.
A High Surf Advisory has been issued for Wednesday evening through Saturday evening for the incoming southerly swell due to Hurricane Genevieve, particularly for south facing beaches exposed to southerly swell (such as from Manhattan Beach to Port Hueneme along the Malibu Coast, and from Long Beach to the Palos Verdes Peninsula). This swell will peak around 3-5 feet at 12-15 seconds from 160-180 degrees.
Additionally, a Coastal Flood Advisory has been issued for Wednesday evening through Friday evening for the Ventura and Los Angeles County Coasts. High tides of 6.2-7.0 feet will peak in the evening hours. In conjunction with the highest expected surf from the Hurricane Genevieve southerly swell, the best potential for minor coastal flooding impacts is expected Wednesday and Thursday evening. Generally minor impacts are expected, such as pooling of seawater over low lying coastal areas in susceptible areas.
Ca, Beach Hazards Statement in effect through Wednesday afternoon for zones 87-354-362-366. (See LAXCFWLOX). Coastal Flood Advisory in effect from 5 PM Wednesday to 3 AM PDT Saturday for zones 87-354-362-366. (See LAXCFWLOX). High Surf Advisory in effect from 5 PM Wednesday to 5 PM PDT Saturday for zones 87-354-362-366. (See LAXCFWLOX). Beach Hazards Statement in effect through Saturday afternoon for zones 340-346. (See LAXCFWLOX). PZ, Small Craft Advisory in effect from 2 PM this afternoon to 9 PM PDT this evening for zone 645. (See LAXMWWLOX). Small Craft Advisory in effect until 3 PM PDT Wednesday for zones 670-673-676. (See LAXMWWLOX).
