textproduct: Los Angeles

SYNOPSIS

03/1251 AM.

Quiet pattern through Friday with below normal temperatures, occasional patchy marine layer clouds, and breezy onshore winds. There is the potential for widespread light showers with increasing temperatures and humidity over Labor Day Weekend. Increasing southerly swell will create hazardous surf conditions at the coasts.

LONG TERM (SUN-WED)

03/117 AM.

As Marie tracks northwest, some of its moisture is forecast to be siphoned into Southern California by the cyclonic flow of the upper low (trough) and the anticyclonic flow of the upper level ridge over the Central US. This northwest track for Marie has all but shut the door on the potential for very significant impacts over our area such as significant winds or flooding, but a very, very small chance for higher impacts does still exist. There is a moderate to high chance of widespread relatively rain (focused south of Point Concpetion) starting on Sunday and continuing into Tuesday. While most members of the European Ensemble are showing little to very light rainfall, there are still a few that show over an inch of rain, so there still is potential for some more moderate rainfall. Additionally, there is a 5-10% chance of thunderstorms focused Sunday. Overall southern California can expect a slight warm up with more humid conditions along with periods of rain which could certainly dampen outdoor plans. Additionally, very strong rip currents and large surf are expected. Refer to the beaches section below for further details.

Starting Wednesday the GFS and EC begin to tell very stories. The GFS favors that trough dipping down in the Central California which would bring cooler temperatures and likely some fairly breezy southwest onshore flow. The EC marches that ridge west into the 4 Corners, bring much warmer temperatures and even the chance for monsoonal convection with increased humidity.

AVIATION

03/0540Z.

At 0409Z at KLAX, the marine layer was 700 feet deep. The top of the inversion was 1300 feet with a temperature of 23 degrees Celsius.

High confidence in VFR conditions for KPRB, KSBA, KBUR, KVNY, KPMD and KWJF. 10% chance for brief IFR-MVFR conds at KPRB/KBUR/KVNY 12Z-17Z.

Low confidence in flight cat at KSBP/KSMX due to patchy stratus. Cats may drop as low as VLIFR with 1/4SM FG at times, and cigs may SCT. Better coverage and deeper cigs after 00Z/04.

Moderate to high confidence in VFR conds at KSBA/KOXR/KCMA. 20% chance for brief IFR-MVFR cigs at KOXR/KCMA between 13Z-17Z.

Low confidence in TAFs for KLAX/KLGB/KSMO. 40% chance no low clouds tonight at KLGB. 40% for low clouds to occur at KLAX/KSMO from 12Z-17Z.

KLAX...Low confidence in TAF. 40% chance BKN008-012 cigs 12Z-17Z. Good confidence in any east wind component remaining below 8 kt.

KBUR...High confidence in TAF, with a 10% chance for brief IFR- MVFR conds 12Z-17Z.

MARINE

03/1252 AM.

Moderate confidence in period of Small Craft Advisory (SCA) northwest winds across portions of the Outer Waters at times through Labor Day Weekend, with highest confidence over the next 24 hours southwest of Point Sal. Local SCA wind gusts may occur in the afternoon-evening hours in the nearshore waters along the Central Coast.

Moderate confidence in SCA west winds through western and southern portions of the Santa Barbara Channel once again this afternoon, with lower chances compared to yesterday, with lowering chances Friday through Labor Day Weekend. Local SCA gusts may occur this afternoon and evening across the Santa Monica Bay and San Pedro Channel, with lowering winds over Labor Day Weekend.

Expecting increasing southerly swell Friday through Labor Day Weekend weekend due to tropical activity to the south. Much of the guidance indicates a northwestward track of Hurricane Marie well away from Southern California, but still a larger than normal southerly swell may create breaking waves at exposed south facing harbor entrances south of Point Conception. Additionally, widespread light rain is likely Saturday-Tuesday, especially south of Point Conception, with a 5-10% chance of thunderstorms.

BEACHES

03/1252 AM.

Guidance is starting to fall into much better agreement that Hurricane Marie will take northwestward track well away from Southern California. However, a large southerly swell will still impacts much of SoCal Friday through Tuesday. This most likely track would produce elevated surf for south facing beaches (with possible high surf advisories) 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. The Central Coast will likely see some elevated surf and rip currents, but not to the magnitude of southern areas.

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, with highest probabilities across Los Angeles and Ventura Counties.

Some areas that may be most susceptible to impacts from the combined elevated surf and high tides are Avalon, Long Beach (Alamitos Peninsula), Malibu, and Point Mugu.

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 until 3 AM PDT early this morning for zone 650. (See LAXMWWLOX). Small Craft Advisory in effect from 3 PM this afternoon to 3 AM PDT Friday for zone 650. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PDT Friday for zones 673-676. (See LAXMWWLOX).