Valley fog, foothill sun – warm weekend ahead

January 12, 2018 – Dry through the weekend with above normal temperatures. Night and morning valley fog likely each day. Next chance of precipitation Monday night through much of next week. Some snow at pass levels.

Discussion

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Upper level high pressure ridge over the west coast bringing mainly clear skies over the forecast area this morning. Fair skies, stable conditions and residual surface moisture from recent rains has allowed for valley fog again this morning. Visibility has dropped one quarter mile or less in several locations so will likely need a dense fog advisory for the delta, southern Sacramento and northern San Joaquin valleys. This fog should mostly clear by late morning but some lingering clouds may remain through the afternoon. Otherwise, warming airmass will bring daytime highs today up to several degrees above normal. Upper ridge centers over the west coast Saturday morning so stable conditions and night or morning fog are likely again. Temperatures will see another notch upward on Saturday. Little change is expected on Sunday as the upper ridge axis shifts slowly east of interior northern California. Upper ridge forecast to break down beginning Monday as a Pacific Frontal system moves into northern California. By afternoon, the coast range could begin to see some light rain with a transition to a wetter period beginning Monday night.

Extended discussion (Tuesday through Friday)

Wet weather returns early next week as a system moves the area Tuesday. Precipitation is expected to be relatively light. Snow levels will initially be above pass levels, dropping below with light snow accumulations expected. Lingering mainly mountain precipitation Wednesday.

Another system is expected Thursday into Friday. This will be cooler with lower snow levels. This could bring enough snow accumulation to cause travel problems in the mountains. Stay tuned to see how this system develops.