January 8, 2021 – Light Valley showers and mountain snow showers possible through this morning, followed by drier conditions this afternoon. Dry and mild weather is forecast this weekend with patchy morning fog.
Discussion
Patches of thicker fog have developed early this morning in the northern San Joaquin Valley ahead of the front. Radar imagery is showing light precipitation tracking through interior NorCal early this morning as a weak Pacific system moves through the region. Observed precipitation amounts have been light so far, ranging from a few hundredths of an inch to around 0.30 inches over the Coastal Range. Additional QPF amounts will be less than a tenth of an inch to around 0.20″ in the Valley and up to 0.30″-0.40″ over the mountains. Best chances still appear to remain north of I-80.
Generally less than an inch of snow is forecast at pass level, locally up to 4 inches near Lassen National Park. Only light snow accumulations are expected, but some mountain travel delays may occur early this morning. Showers will taper off this morning as the system exits the region, with dry conditions returning in the afternoon. The exception could be a few lingering showers over the Sierra north of I-80.
Morning fog will be possible through the forecast period as a high pressure pattern remains in place. Northerly flow could limit fog formation on Saturday morning over the west side of the valley with a good chance for formation over the eastern side where winds should become light. Latest HREF indicates the best chances for fog formation should be in the southern Sacramento and northern San Joaquin valleys. Clouds pushing into the region Saturday night may limit fog formation.
Ensembles depict a ridge of high pressure setting up over the region this weekend into next week. This stable pattern will deflect storms well northward, and keep interior NorCal dry. Daytime temperatures will trend milder, with Valley highs in the upper 50s to low 60s.
Extended discussion (Tuesday through Friday)
Strong ridging next week will result in generally dry conditions with daytime temperatures well above average.