Swell Matrix

Area Forecast Discussion

National Weather Service Los Angeles/Oxnard Ca

517 pm PDT Wed Sep 28 2022

Synopsis

28/142 PM.

A cooling trend will begin in all areas Thursday and continue into the weekend with increasing night to morning low clouds and onshore winds.

Short Term

(tdy-Sat), 28/140 PM.

Weakening high pressure and increasing onshore flow will bring about a cooling trend area-wide that will continue into the weekend. Temperatures expected to return to normal or even a little below normal by Saturday in most areas. The only exception being the Antelope Valley and far interior SLO County where temps will remain 2-5 degrees above normal.

The increasing onshore flow and cooling aloft should help the marine layer become more widespread along the coast by this weekend as well. And possibly even sneaking into some of the valleys. Another night or two of locally gusty Sundowner winds across southern Santa Barbara County. With northerly flow weakening winds should remain below advisory levels. Overall a very quiet weather pattern the next few days at least with minimal impactful weather issues short of possibly some airport delays due to dense fog at times.

Long Term

(Sun-Wed), 28/157 PM.

Ensembles are clustered closely together through at least Tuesday leading to good confidence in the forecast through early next week. High pressure is expected to start to rebuild Sunday into Monday resulting in a minor warming trend that will continue into Tuesday. Much bigger spread in the model solutions from mid week on as some models (mostly the EPS) showing a slow moving upper low approaching northwest CA. A few solutions show some rain locally but the vast majority are dry and that's certainly the most likely scenario.

Aviation

29/0015z.

At 2327Z, the marine layer depth was around 600 feet deep at KLAX. The top of the inversion was near 2300 feet with a temperature of 30 degrees Celsius.

High confidence in the current forecast for valley and desert terminals. Moderate confidence in the current forecast for coastal terminals, mostly due to uncertainty in the timing of cigs. There is also a low chance (30%) for cigs to reach KOXR and KCMA.

KLAX, There is a 30 percent chance of LIFR to IFR conditions after 08Z. Timing could be off by up to two hours. Any easterly winds should be less than 7 knots.

KBUR, VFR conditions are expected through the period.

Marine

28/129 PM.

No changes to the marine forecast in the afternoon issuance.

For the waters from southwest through northwest of the Channel Islands and along the Central Coast, widespread Small Craft Advisory (SCA) conditions will very likely persist through at least late Thursday evening. There is a moderate (50 percent) chance that SCA conditions could extend into early Friday morning. Winds will likely be strongest during the afternoon and evening hours, extending into the nearshore waters along the Central Coast. Winds and seas should drop below SCA levels on Friday. In addition, a shallow marine layer through could produce dense fog tonight through Wednesday morning, at times reducing visibility to one nautical mile or less.

Inside the southern California bight, there is a moderate-to-high (40-60 percent) chance of SCA levels winds with choppy short period seas. The highest chance of SCA level winds will be across the western portion of the Santa Barbara Channel Wednesday and Thursday afternoon and evenings, but locally gusty winds could occur across the Santa Monica Bay and into the San Pedro Channel. Otherwise, winds and seas will likely remain below SCA levels.

Watches, Warnings, Advisories

Ca, Excessive Heat Warning in effect until 8 PM PDT this evening for zones 88-363-547-548. (See LAXNPWLOX). Heat Advisory in effect until 8 PM PDT this evening for zones 356>359. (See LAXNPWLOX). PZ, Small Craft Advisory in effect until 9 PM PDT this evening for zones 645-650. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PDT Friday for zone 670. (See LAXMWWLOX). Small Craft Advisory in effect until 9 PM PDT Thursday for zones 673-676. (See LAXMWWLOX).

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