textproduct: Los Angeles

SYNOPSIS

14/1140 PM.

A significant heat wave will kick off today, peak next Tuesday and Wednesday, and then continue through Friday. MODERATE to HIGH heat impacts will occur each day Monday through Friday.

LONG TERM (WED-SAT)

15/207 AM.

There will be little change in the synoptic features on Thursday and max and min temps will remain very close to the record values of Tue and Wed. On Friday the upper high shifts a little to the SE and hgts fall some. This will also move the area of maximum synoptic subsidence (and thus compressional heating) away from the fcst area. In addition the offshore flow will weaken some. These items will all add up to 2 to 4 degrees of cooling. This cooling will not be enough to offset the dangerous heat. The EXTREME HEAT WATCHES do continue through Friday evening and will very likely be converted to warnings with the afternoon forecast package.

Another 2 to 4 degrees of cooling on Saturday should be enough to eliminate the warning level heat risk but the vlys will likely still need heat advisories.

Given the unprecedented length and magnitude of this extreme heat wave, heat stress will be a real threat each day, especially in areas that aren't used to the heat, like the coastal areas, where people may not have methods to cool off their homes. Try to complete outdoor activities early in the day or in the evening, and don't leave people or pets in cars.

Long range AI mdls are mostly dry through the 28th, but they do show increasing chances rain over the north half of the state and a chc of light showers over portions of SoCal on the 25th or 26th.

AVIATION

15/1013Z.

At 0845Z at KLAX, the marine layer was 1000 ft deep. The top of the inversion was at 1800 ft with a temperature of 19 C.

High confidence in TAFs for KPRB, KSBP, KSMX, KBUR, KVNY, KPMD and KWJF.

Moderate confidence in the remainder of the TAFs through 18Z then high confidence. Flight cat transitions could be off by +/- 2 hours.

KLAX...Moderate confidence in TAF through 18Z due to +/- 2 hour potential timing differences of flight cat changes. Good confidence in TAF from 18Z-04Z followed by moderate confidence with timing of return of low clouds and a 30 percent chc of no low clouds at all. Good confidence that any east wind component will be below 7 kts.

KBUR...High confidence in VFR TAF.

MARINE

15/1201 AM.

Small Craft Advisory (SCA) conditions will linger into late Sunday night across the Outer Waters. Thereafter, conditions will likely remain benign through at least mid-week. Moderate chances for SCA winds starting Thursday or Friday across the northern waters.

For the Inner waters along the Central Coast, localized SCA level NW winds likely south of Port San Luis Sunday afternoon into the early evening hours. Otherwise, conditions are expected to remain benign through at least mid-week.

Inside the Southern California Bight, conditions are expected to remain below SCA levels for the foreseeable future.

LOX WATCHES/WARNINGS/ADVISORIES

CA...Heat Advisory remains in effect from 10 AM to 8 PM PDT Monday for zones 87-88-340>342-345>358-362-366>376-378>380-548. (See LAXNPWLOX). Extreme Heat Watch in effect from Monday evening through Friday evening for zones 87-88-340>342-345>358-362-366>376-378>380-548>550. (See LAXNPWLOX). PZ...NONE.