Area Forecast Discussion

SYNOPSIS

06/322 AM.

Temperatures will remain near to slightly below normal through at least early next week as a series of low pressure systems move through the region. Low clouds and fog will cover most of the coast and valley locations through at least mid morning, clearing to near the beaches each afternoon. A warming trend is expected later next week.

SHORT TERM (TDY-MON)

06/853 AM.

***UPDATE***

The marine layer continues to deepen as the upper low over the Pac NW moves south. Cloud tops near 3000 feet have been reported by pilots in the LA Basin while the VBG sounding measured tops around 2000 feet earlier this morning. So June gloom continues today and likely at least through the weekend. Clouds should clear all the valleys before noon but closer to the coast clouds may linger all day, especially between Malibu and Santa Barbara as the south to north gradients have been peaking around 6 mb each day and currently trending 1-2mb more onshore. So another relatively cool day at the coast while coastal valleys top out in the mid 70s to lower 80s, roughly 5 degrees below normal. Even the deserts will fall short of 90 today.

***From Previous Discussion***

A large upper level low is currently situated over the PAC NW. Although this energy is expected to remain well to the north, 500mb heights over our area will respond accordingly and will reach the lowest values on Sunday 576-578dm. Onshore flow will persist. The combination of these factors will result in classic June gloom low clouds and patchy fog across the coasts & valleys. Marine layer will become deepest on Sunday around 3500 ft and perhaps a bit more shallower along the Central Coast. Late clearing of marine layer stratus expected inland, and minimal to no clearing near the beaches south of Point Conception.

Max Temperatures will be noticeably cooler well inland across the far interior. And fairly similar to yesterday along the coasts. Minor differences on Sunday - some areas slightly cooler or slightly warmer.

Moderate chance (30-40%) of advisory level Sundowners on Sunday. Guidance shows -3 to -4 mb SBA-SMX pressure gradient. This would be focused across areas west of San Marco Pass. A bit better chance on Monday (40-50%).

LONG TERM (TUE-FRI)

06/322 AM.

Ridging is expected to build in from the west starting Tuesday. Onshore flow in general is expected to persist through the fcst period. About 15% of ECWMF members show light to moderate offshore flow Wednesday through Friday (LAX-DAG). Not buying these solutions as they are unfavorable climatologically. By the end of the week, most areas should be at least slightly above normal. NBM probs show 10-15% chance of reaching 100F across Antelope valley Thursday and Friday. 10-20% chance of reaching 90F Wednesday through Friday across San Fernando and Santa Clarita valleys.

There is a 60% chance of advisory level sundowners Tuesday. Weak northerly flow indicated by SBA-BFL ECWMF projections would likely result in the strongest winds focused a bit eastward (Refugio area). Low confidence in wednesday due to large spread in guidance, but leaning towards less of a chance, and even lower Thursday into Friday.

LAX-BFL is projected to decrease quickly from 3-4mb Monday evening to negative 2 to -3mb Tuesday morning. If this occurs, there is a likely (60% chc) of advisory level NW-N winds across the I-5 corridor Tues into Wednesday morning. This trend is expected to reverse Wednesday into Friday (onshore) which could result in advisory winds across the Antelope Valley, but confidence is fairly low at this time.

AVIATION

06/1724Z.

At 1630Z at KLAX, the marine layer was 2500 feet deep. The top of the inversion was 4400 feet with a temperature of 19 degrees Celsius.

For 18Z TAF package, high confidence in forecasts for KWJF, KWJF and KPRB. For all other sites, moderate confidence in forecasts due to uncertainties with behavior of the marine layer. Timing of flight category changes could be +/- 3 hours of current forecasts.

KLAX...Moderate confidence in 18Z TAF. There is a 40% chance that MVFR CIGs do not scatter out this afternoon. No significant easterly wind component is expected.

KBUR...Moderate confidence in 18Z TAF. Timing of flight category changes could be +/- 3 hours of current forecast.

MARINE

06/848 AM.

For the Outer Waters, moderate to high confidence in current forecast. Through Wednesday, high confidence in a combination of Small Craft Advisory (SCA) level winds and seas. Additionally, there is a 60-80% chance of GALE force winds across PZZ670/673 today and tonight and GALE WARNINGs are in effect for these areas. From Sunday through Wednesday, there will be a 20-30% chance of Gale force winds.

For the Inner Waters north of Point Sal, high confidence in current forecast. Through this morning, winds and seas will remain below SCA levels. From this afternoon through Wednesday, SCA level winds are expected during the afternoon and evening hours, along with seas approaching SCA levels.

For the Inner Waters south of Point Conception, moderate confidence in current forecast. For a majority of the southern Inner Waters, high confidence in winds and seas remaining below SCA levels through Wednesday. The only exception will be the western half of the Santa Barbara Channel, where there is a 40-60% chance of SCA level winds Monday through Wednesday, mainly in the late afternoon and evening hours.

LOX WATCHES / WARNINGS / ADVISORIES

CA...NONE. PZ...Small Craft Advisory in effect from 3 PM this afternoon to 3 AM PDT Sunday for zone 645. (See LAXMWWLOX). Gale Warning in effect until 3 AM PDT Sunday for zone 670. (See LAXMWWLOX). Small Craft Advisory in effect until 3 PM PDT this afternoon for zone 673. (See LAXMWWLOX). Gale Warning in effect from 3 PM this afternoon to 3 AM PDT Sunday for zone 673. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PDT Sunday for zone 676. (See LAXMWWLOX).