December 27, 2020 – Dry weather is expected through this afternoon before another weather system impacts the area tonight into Monday. Dry weather returns with possible valley fog for Tuesday and Wednesday before another weak system impacts the region Wednesday night into Thursday.
Dry weather and high clouds are noted across Northern California early this morning. These clouds have limited fog potential, although models indicate some patchy fog could develop on the eastern side of the southern Sacramento and northern San Joaquin Valley near sunrise.
Mostly cloudy skies continue today as a closed low digs over the eastern Pacific and traverses over central and southern California late Sunday and Monday. With the track of this system, precipitation will mainly be limited to the southern half of the CWA.
Snow showers may begin as early as the late afternoon, mainly limited to the mountains of Tuolumne and Alpine Counties. The better chances for precipitation look to be late tonight into Monday morning when a few scattered showers will also be possible in the Valley.
Overall, precipitation does not look too impressive with this system, and in the Valley and foothills, less than a quarter of an inch of QPF is expected with some locations being missed completely by showers.
As for the Sierra, a few inches of snow will be possible mainly from I- 80 southward. Amounts range from about 1 to 6 inches, locally higher on peaks with snow levels generally 4000 to 4500 feet or above.
Any remaining showers will be ending Monday evening. Some light northerly flow will develop behind the system that should limit fog formation on Tuesday morning over the west end of the valley with decent chances for formation over the eastern side where winds should become light. Fog may again return Wednesday morning ahead of another system which may bring additional precipitation to the area as early as Wednesday afternoon.
Extended discussion (Thursday through Sunday)
A break in the wet weather will continue during the day Wednesday before a weak system moves through Wednesday night into Thursday. Only light precipitation expected with this system at this time.
A more significant system is possible during the New Year’s Holiday Weekend, but model difference make determining any fine details difficult this far out. Valley high temperatures will be near normal values in the low and mid 50’s.