textproduct: Los Angeles

SYNOPSIS

31/357 AM.

A hot air mass will continue over the region through much of the week as high pressure aloft will remain anchored near the Four Corners region. Monsoonal moisture will arrive again on Tuesday and keep a low but present risk of showers and thunderstorms through the remainder of the week. A cooling trend is possible for the upcoming weekend.

LONG TERM (WED-SAT)

31/354 AM.

High pressure aloft, albeit weaker, will linger over the southwestern United States into Wednesday and Thursday. A very warm air mass with added humidity from the Desert Monsoon is likely to persist. Temperatures above seasonal normals should be expected into at least Thursday. There is a moderate chance that heat headlines may be extended into Wednesday or Thursday. With the increased monsoon moisture and overall hot air mass in place, Tuesday night may end up being the warmest night of the week, giving daytime heating a head start for Wednesday. Overnight low temperatures across much of the LA metro area could remain above 70 degrees, while many foothill and mountain areas may see overnight low temperatures in the mid 70s to lower 80s, adding to the heat risk.

A cooling trend should develop on Friday and into next weekend. The latest ensemble members shows 500 mb height means trending downward through much of next weekend.

Southeast flow aloft will likely be in place between Tuesday and Friday. The area will sit on the western edge of the monsoon, and there will likely be shower and thunderstorms chances in the forecast each day. The highest chances of showers and thunderstorms will likely persist across the San Gabriel Mountains and Antelope Valley, but there is a chance that an easterly wave could push underneath the ridge into southern California. Chances for showers and thunderstorms cannot be ruled out entirely during the long term period.

AVIATION

31/1158Z.

Around 12Z at KLAX, the marine layer was 500 ft deep. The top of the inversion was at 2800 ft with a temperature of 29 C.

Low confidence in TAFs for KOXR, KCMA, KSMO, KLAX, and KLGB due to uncertainty of low clouds. Timing of flight cat changes may be off +/- 3 hours and minimum cig heights may be off +/- 300 feet. Cigs may scatter and reform frequently through 17Z. There is a 10-30% chance for vsbys less than 1SM, highest chances at KOXR and KCMA.

High confidence in remaining TAFs.

KLAX...Low confidence in TAF until 20Z, high confidence from 20Z Sun to 03Z Mon, then moderate confidence. Cigs may scatter and reform frequently through 17Z, with a 40% chance of no low clouds. If low clouds do arrive, there is a 15% chance for vsbys 1/2SM-1SM at times due to shallow marine layer. Timing of flight cat changes may be off +/- 3 hours and minimum cig height may be off 300 feet. Good confidence that any east wind component will remain below 7 kt.

KBUR...High confidence in TAF.

MARINE

31/241 AM.

High confidence in 20-30 kt NW winds across the Outer Waters from Point Sal north to Point Piedras Blancas continuing through Labor Day (Monday), with moderate confidence in local gusts up to 35 kt during the afternoon and evening hours today. Moderate confidence in the remaining Outer Waters remaining below Small Craft Advisory (SCA) criteria through this morning, with a 30% chance of winds increasing to SCA levels during the afternoon and evening hours today and Monday. Tuesday into Thursday, the best chances for SCA winds are focused around Point Conception south to San Nicolas Island. A relative lull in winds will be likely each morning.

Moderate confidence in forecast for the nearshore waters along the central coast, with a 30% chance of SCA conds in the afternoon and evenings today and Monday, then lighter winds and smaller seas likely.

Aside from fairly seasonal afternoon and evening localized NW wind gusts 20-25 kts in the far Western Portion of the Santa Barbara Channel and 15-20 kts in the San Pedro Channel, light winds and small seas will be common for the nearshore waters south of Point Conception through Labor Day. Better chances for more widespread SCA winds on Tuesday through Thursday during the afternoon and evenings.

LOX WATCHES/WARNINGS/ADVISORIES

CA...Heat Advisory remains in effect from 10 AM this morning to 6 PM PDT Tuesday for zones 38-344-345-353. (See LAXNPWLOX). Heat Advisory in effect from 10 AM this morning to 10 AM PDT Monday for zones 88-352-356>358-369>375. (See LAXNPWLOX). Heat Advisory now in effect from 10 AM Monday to 6 PM PDT Tuesday for zones 88-356>358-368>376-378-379-548. (See LAXNPWLOX). Beach Hazards Statement in effect through Monday evening for zones 340-346-354-362-366. (See LAXCFWLOX). Heat Advisory remains in effect from 10 AM this morning to 6 PM PDT this evening for zones 341>343-347>349-351. (See LAXNPWLOX). Heat Advisory in effect from 10 AM this morning to 6 PM PDT this evening for zone 355. (See LAXNPWLOX). PZ...Small Craft Advisory in effect until 3 AM PDT Monday for zone 670. (See LAXMWWLOX).