textproduct: Los Angeles

SYNOPSIS

02/100 AM.

Stagnant pattern through Friday with below normal temperatures, occasional patchy marine layer clouds, and weak to moderate Sundowner winds. Several potential scenarios exist for the Labor Day weekend, with anything from benign conditions to tropical rain, or even hot offshore winds.

LONG TERM (SAT-TUE)

01/932 PM.

For the long term period, an upper low is forecast to wobble over and around the Pacific Northwest through the Labor Day weekend. Models vary on the exact path of the wobble, but cyclonic flow aloft will remain over the area through early next week. At the surface, focus remains on current Tropical Storm Marie. While some more models/ensemble members are starting to come into agreement with a more northwestward track away from SW California, still quite a bit of uncertainty in exact details for impacts across the region this weekend.

Currently, Marie is located between 15N and 20 N, and around 110W. The latest forecast from the National Hurricane Center has Marie intensifying to hurricane strength early this morning, following a track to the northwest through the Labor Day weekend. The chances of Marie directly hitting Southern California as a hurricane or tropical storm remain VERY LOW (with only a few ensemble members from the models indicate any track close to Southern California).

However, despite the HIGH likelihood of Marie maintaining a west to northwest track away from the West Coast, there still be some noticeable impacts for the area from this storm. With the upper level pattern, moisture from Marie will be advected over the area during the Labor Day weekend, but the amount of moisture will be greatly impacted by the exact track of the hurricane. At this time, there is a 50-60% chance of widespread light rainfall (amounts 0.10-0.50 inches) Sunday through Tuesday and about a 10-15% chance of heavy rainfall and thunderstorms. As for winds, there will be about a 10-15% chance of moderate to strong easterly winds ahead of any rainfall, which could produce some fire weather concerns. Finally, there is high confidence in significant coastal risks which are detailed in the Marine and Beaches segments of this discussion.

Needless to say, the weather for the upcoming Labor Day weekend may by highly dynamic. A minor change in the track of Marie could result in significant changes to the current forecast. So, given the uncertainty with this pattern, stay tuned and monitor the latest forecasts.

AVIATION

02/0519Z.

At 0439Z at KLAX, the marine layer was 1100 feet deep with an inversion at 2500 feet and 21 degrees C.

High confidence on VFR TAFs at KPRB, KSBA, KOXR, KCMA, KBUR, KVNY KWJF, and KPMD. 10% chance for very brief MVFR cigs at coastal sites sometime between 12Z-17Z.

Low to moderate confidence in SCT to BKN MVFR conds for remaining sites, with best chance of cigs at KSMX/KSBP. Small chance for IFR conds at those sites. 50% chance for VFR conds to prevail at KLGB, and 30% chance for very brief MVFR cigs at coastal sites sometime between 12Z-17Z at KLAX/KSMO.

KLAX...Moderate confidence in TAF. There is a 30% chance for brief BKN012-015 cigs developing sometime from 12Z-17Z. No significant east wind component expected.

KBUR...High confidence in TAF otherwise, with a 10% chance for brief BKN0010-15 cigs from 12-16Z.

MARINE

02/1258 AM.

High confidence for Small Craft Advisory (SCA) level winds and short period seas across the Outer Waters southwest of Point Sal through Thursday, with slightly lower chances across all Outer Waters Friday through Labor Day Weekend. While unlikely to be widespread enough for a SCA across the nearshore waters along the Central Coast, winds may reach 20-25 knots locally each afternoon/evening.

Good confidence in more widespread SCA level west winds and choppy seas through the Santa Barbara Channel this afternoon and evening, including eastern portions. Winds are forecast to weaken thereafter, but there remains a 50% chance for SCA west winds across the western portion Thursday. Local gusts of 20-25 knots may be common through the Santa Monica Bay and San Pedro Channel in the afternoon and evening hours today and Thursday.

Expecting increasing southerly swell Friday through Labor Day Weekend weekend due to tropical activity to the south. The details and timing are very much dependent on the track of soon to be Hurricane Marie, but confidence is high in larger than normal southerly swell through the holiday weekend and into Tuesday.

BEACHES

02/1258 AM.

While there remains a range of outcomes in terms of the track of son to be Hurricane Marie, SoCal is likely to see an increasing south-southeasterly swell Friday into Tuesday. The most likely scenario would result in elevated surf with possible high surf advisories for south facing beaches during a very busy holiday weekend, with very strong rip currents. Peak timing is still somewhat unclear, but Sunday through Monday appear to be the window of peak swell.

Additionally, evening high tides are expected to be around 7 feet during portions of the event. As a result, there is an increasing chance of moderate coastal flooding of low- lying areas and significant beach erosion. There is a chance that coastal flood advisories will be issued.

Some areas that may be most susceptible to impacts from the combined elevated surf and high tides are Avalon, Long Beach (Alamitos Peninsula), Malibu, Point Mugu, and potentially portions of Santa Barbara (if the swell directions ends up being 160-170 degrees).

LOX WATCHES/WARNINGS/ADVISORIES

CA...Wind Advisory in effect until 6 AM PDT early this morning for zones 349-351. (See LAXNPWLOX). PZ...Small Craft Advisory in effect from 3 PM this afternoon to 3 AM PDT Thursday for zone 650. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PDT Thursday for zones 673-676. (See LAXMWWLOX).