Swell Matrix

Area Forecast Discussion

National Weather Service Los Angeles/Oxnard Ca

442 am PST Tue Jan 18 2022

Synopsis

18/219 AM.

Mostly cloudy skies will turn partly cloudy this afternoon. Then, aside from some coastal low clouds Wednesday morning, skies will fair through the next 7 days. There will be warming most days and the high temperatures will rise to above normal on Thursday. Breezy Santa Ana conditions will affect the area on Thursday and Saturday.

Short Term

(tdy-Thu), 18/259 AM.

The upper low that passes over the area last evening has opened up into a broad trof and is now moving into NV. There are a few lingering showers but most have dissipated. Only a slight chc of shower remains this morning across LA county. Plenty of clouds and some fog remain in the wake of the low, but these clouds should clear enough to make it partly cloudy afternoon for most of the area. Rising hgts and little more sunshine will bring 2 to 5 degrees of warming to most areas today. Max temps, however, will remain several degrees blo normal.

A small ridge will start to push into the area on Wednesday. There will be a switch to onshore flow which will likely produce some morning low clouds across the coasts and some of the lower vlys. Otherwise skies will be sunny and max temps will rise 3 to 6 degrees away from the coast as hgts rise but the onshore flow will bring a few degrees of cooling to the coasts.

Full on ridging will cover the state on Thursday. Hgts will rise to 582 dam over Srn CA. The ridge will be very positively tilted and this will bring some upper level offshore flow to the southern third of the state. At the same time sfc high pressure over NV will bring 3 to 5 mb of offshore flow to the area both from the N and the E. This will likely generate a low end advisory level Santa Ana wind event for the typical locations across LA and VTA counties. Some cool air spilling in from the high deserts will knock 3 to 4 degrees off of the max temps of the Antelope Vly and LA mtns but the rest of the area will see 5 to 10 degrees of warming. Thursday will be the day where the entire area has above normal max temps.

Long Term

(Fri-Mon), 18/318 AM.

EC/GFS ensembles as well as the deterministic run are in pretty good agreement for the extended period. This gives us a fairly good confidence in the forecast.

Friday will be a benign day with dry NW flow overhead and weak offshore flow at the sfc. Due to the much weaker offshore flow and lack of cold air advection the temp change will be the opposite of Thursday will warming across the Antelope Vly and LA mtns and cooling over most of the rest of the areas. Still max temps will exceed normals.

An upper low rotating through the Great Basin will shift the upper level over Srn Ca to the NE. At the same time SFC high pressure building into NV will bring moderate offshore flow to the area. These two things along with a slug of cold air advection will bring another advisory level Santa Ana wind event to the area. Like Thursday the compressional downslope heating driven by the offshore flow will bring warming to the area xcp for the LA mtns and Antelope Vly where the cool air advection will lower max temps by 2 to 4 degrees.

Ridging and weaker onshore flow will be the order of the day both Sun and next Mon. Skies will be mostly clear. Rising hgts will warm the interior while weaker offshore flow will allow an earlier sea breeze and cooling for the coasts.

Aviation

18/1241z.

At 0845Z at KLAX, there no marine layer nor a sfc based inversion, but there was a moist layer up to 8000 feet.

Low confidence in TAFs through 20Z then fair confidence. Cigs will change frequently. Cigs will mostly be range from 015 to 035 but there is a 30 percent chc IFR-LIFR conds through 18Z. There is a 30 percent chc of BKN040-050 conds during the afternoon hours.

Low confidence in exact arrival times and hgts of cigs at coastal terminals aft 05Z.

KLAX, Low confidence in TAF through 20Z then fair confidence. Cigs will fluctuate from IFR to low VFR. There is a 30 percent chc of brief showers through 18Z. There is a 30 percent chc of BKN050 conds 20Z-01Z Any east wind component should not exceed 6 kt.

KBUR, Low confidence in TAF through 20Z then fair confidence. Cigs will change frequently. Cigs will mostly be range from 025 to 035 but there is a 30 percent chc of BKN015 conds through 18Z. There is a 30 percent chc of BKN040-050 conds during the afternoon hours.

Marine

18/246 AM.

There is a 30% chance of Small Craft Advisory level NW winds across the western portion of the outer waters Tue night thru Wed night. Otherwise, winds and seas are expected to remain below SCA levels thru the period.

Watches, Warnings, Advisories

Ca, NONE. PZ, NONE.

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