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November 27, 2017 – Rain and breezy winds will continue through the early morning hours. Mountain travel impacts as snow levels drop to 5000 feet. Mainly drier weather Tuesday through Friday with patchy morning fog in the valley. Next chance of precipitation next weekend.

Winter Weather Advisory until 10 AM this morning.

Discussion

Back edge of cold front now moving through the northern Sierra bringing scattered showers. Snow levels have been lowering and Blue canyon at 5000 feet has switched over the snow over the last hour. This front is bringing gusty winds as well with isolated locations seeing winds in excess of 40 mph. A secondary cold front is now moving into the Sacramento valley bringing moderate to occasionally heavy rainfall. HRR model moves frontal precipitation into the Sierra between about 12 and 14z.

Snow levels may drop a little below 5000 feet but additional snow amounts more than an inch or two should remain above 7000 feet so will leave winter weather advisory in place as is for now. The secondary front with shift east of the forecast area by 18z today as the main associated upper low shifts into the Great Basin. Building upper ridge will bring drying and clearing skies by this afternoon.

Cooler air associated with the low will bring daytime highs today down to near or a little below normal for this time of year. Upper ridge will slide over the west coast tonight. Fair skies, stable conditions and surface moisture will make valley fog a good bet tonight. Another shortwave trough will flatten the west coast ridge Tuesday afternoon and evening bringing a slight threat of showers to the Shasta county mountains but the remainder of the forecast area should stay dry with little impact expected. The trough is forecast to shift east of the state by Wednesday morning with rebuilding upper ridging bringing enough clearing for a return of morning valley fog. Ridging and clearing skies will bring daytime highs back up to above normal Wednesday with still more warming on Thursday.

Extended discussion (Friday through Monday)

The next weather system will drop southward out of the Gulf of Alaska late Friday into Saturday spreading precipitation across the region. EC and GFS now in better agreement lending increased confidence in the forecast of a colder system moving through over the weekend. Snow levels lower to 2500-3500 feet by early Sunday. Showers then forecast to end by later Sunday as the trough shifts east with dry weather expected early next week.