January 25, 2018 – Pacific storm impacts the area thru Friday with periods of showers and a few thunderstorms, mountain snow and breezy wind.
Discussion
Much of interior NorCal is seeing a relative break early this morning as precip associated with the front has shifted into central California while showers are spreading across NW California ahead of the approaching upper trough. Clearing at the north end of the Sacramento Valley, along with light winds, has allowed some dense fog to develop.
Showers, along with a few thunderstorms (small hail will be the primary threat), will increase across the region today as the upper trough moves overhead. The convective nature of this precip will give rise to potential large variability in snowfall with some areas picking up very heavy amounts. Mountain snow showers will linger into early Friday, but taper off by afternoon.
Storm track shifts north over the weekend with precip chances confined to Shasta county, Coastal range and the Southern Cascade range. QPF will be light, though snow levels will remain rather low.
Extended discussion (Monday through Thursday)
Ridge of high pressure will bring seasonable and dry conditions to interior NorCal on Sunday. An upper system skirting across the northern fringes of California and the Pacific NW Tuesday will push a weak frontal boundary across the forecast area. Precipitation chances will be limited to the northern mountains as favorable dynamics are forecast to remain to our north. By midweek, ridging from the eastern Pacific will extend into NorCal and push the storm track to our north. Highs are expected to be near or slightly above seasonal normals through the extended forecast.