textproduct: Los Angeles

SYNOPSIS

25/222 AM.

Very hot conditions will dominate the week, with a high risk for heat illness. Patchy night through morning low clouds and locally dense fog will be confined to some coastal areas. Significant cooling is likely over the weekend but it will remain warm.

LONG TERM (FRI-MON)

25/223 AM.

A substantial trof will move into the west coast and push the upper high to the south. The flow will slowly switch to the SW during the period and hgts will fall to 588 dam. Some offshore flow may persist in the morning esp from the north, but the afternoon onshore push to the east will increase.

Most max temps will fall 1 to 2 degrees on Friday (except for the Central Coast where better onshore flow will bring 3 to 6 degrees of cooling). This small amount of cooling will not be enough to eliminate the heat risk and all warnings and advisories will continue. Look for 5 to 10 degrees of cooling across the csts/vly on Saturday as the trof and onshore flow really begin to affect the weather (the mtns and far interior will see 2 to 4 degrees of cooling). On Sunday all areas will cool 3 to 6 degrees and this will bring many areas to or even below normal max temps. 2 to 4 additional degrees of cooling is likely next Monday and this will reduce coastal max temps to the 70s (upper 60s/lower 70s Central Coast) and in the mid 80s to mid 90s for the vlys.

AVIATION

25/0922Z.

At 0830Z at KLAX, the marine layer was 500 feet deep. The top of the inversion was 2000 feet and 31 C.

High confidence in VFR conditions through at least Tuesday KPRB, KSBA, KBUR, KVNY, KPMD, and KWJF.

For KSBP and KSMX, timing of flight category changes could be +/- 2 hours of current forecast.

Chances of LIFR/IFR ceilings tonight at KOXR (20%) KCMA (20%) KSMO (25%) KLAX (25%) KLGB (25%).

KLAX...Moderate confidence in TAF with a 25 percent chc of 3SM BKN005 conds 12Z-16Z. No significant easterly wind component is expected.

KBUR...High confidence in CAVU TAF.

MARINE

25/223 AM.

For the Outer Waters, high confidence in current forecast. This afternoon through Saturday, SCA level winds are expected across all of the Outer Waters. Seas will remain at SCA levels, initially due to short period combined seas, but approaching 8 to 10 feet by Thursday.

For the Inner Waters north of Point Sal, moderate to high confidence in current forecast. Late this afternoon through late tonight there is a 40-60% chance of SCA winds. For Wednesday through Saturday, there is a 60-80% chance of SCA level winds in the afternoon and evening hours. Short period seas will be common throughout the week, especially during the afternoon to evening.

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 where there is a 60-80% chance of SCA level winds through Saturday in the late afternoon and evening hours.

FIRE WEATHER

24/410 PM.

An extended period of very hot and dry conditions will bring widespread elevated to brief critical fire weather conditions away from the immediate coast through this weekend. The combination of triple digit temperatures, very deep mixing heights of 12,000 to 20,000 feet, locally gusty winds, low humidities, and fuels approaching critical levels will bring the highest risk of large plume dominated fires with rapid fire spread in the interior mountains and adjacent foothills of LA, Ventura, Santa Barbara, and San Luis Obispo counties, as well as the Cuyama Valley, resulting in the Red Flag Warning issuance Tuesday through Friday. These areas can expect minimum humidities of 8 to 20 percent, poor overnight recoveries, and locally gusty northerly winds at times across the interior mountains (strongest in the I-5 and Highway 33 corridors). There is the possibility of a slight enhancement to the northerly winds late Thursday night into Friday morning across the interior mountains, which could result in isolated gusts up to 40 mph in the I-5 corridor. There is a history of large plume dominated fires this time of year with similar weather and fuel conditions, including the Bridge, Bobcat, and Stations fires.

Weak to moderate sundowner winds with hot and dry conditions will likely bring elevated to brief critical fire weather conditions across southern Santa Barbara county through Saturday night, with Tuesday and Saturday events likely strongest and most widespread. Sundowner wind exposed areas could see temperatures soar to between 90 and 100 degrees with humidities falling to between 10 and 25 percent.

LOX WATCHES/WARNINGS/ADVISORIES

CA...Heat Advisory in effect until 10 AM PDT this morning for zones 38-87-88-349>358-362-366>376-378>380-548. (See LAXNPWLOX). Extreme Heat Warning in effect from 10 AM this morning to 8 PM PDT Friday for zones 38-87-88-349>358-362-366>376-378>383-548. (See LAXNPWLOX). Heat Advisory in effect from 10 AM Wednesday to 8 PM PDT Thursday for zones 341-347-348. (See LAXNPWLOX). Heat Advisory in effect from 10 AM this morning to 8 PM PDT Friday for zones 342>345. (See LAXNPWLOX). Red Flag Warning in effect from 10 AM this morning to 3 PM PDT Friday for zones 345-353-375>380. (See LAXRFWLOX). PZ...Small Craft Advisory in effect from 3 PM this afternoon to 3 AM PDT Wednesday for zone 645. (See LAXMWWLOX). Small Craft Advisory in effect from 3 PM this afternoon to 3 AM PDT Thursday for zone 670. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PDT Thursday for zones 673-676. (See LAXMWWLOX).