February 19, 2021 – A weather system will bring a period of snow to the Sierra tonight with possible travel impacts. Thereafter, a warming and drying trend is forecast into next week with above average temperatures expected.
Discussion
Weak trough moving through NorCal will dissipate this morning. Only light showers with this system, generally less than 0.10 of rainfall. Snow showers will diminish with amounts of 1 to 3 inches at pass level through the morning.
A second system will drop southeast through the area tonight into Saturday morning. Model trends have continued wetter and colder with this system and the increased moisture from the 00z run has pushed the Sierra into advisory level snow criteria. Therefore, have issued a winter weather advisory for the Sierra above 4500 feet for 4 to 8 inches of snow from 6pm today through 10 am Saturday. The best chances for travel impacts along I80 and highway 50 over the Sierra will be after midnight.
Upper ridge will build over northern California Sunday and Monday with dry weather and a warming trend. High temperatures warm to mid/upper 60’s Sunday and upper 60’s/low 70’s Monday over Valley locations. Ensembles indicate ridge will begin to flatten Tuesday, as trough slides over the northern Rockies. Clusters favor the flatter solution of the euro instead of the deeper GFS solution. Expect a slight cooling trend with some breezy north winds in the pattern.
Extended discussion (Tuesday through Friday)
Short wave trough rides the EPAC upper ridge into the PacNW Tuesday with associated precipitation remaining north of the CWA. Another wave follows Wednesday with EC trying to bring its track farther west through interior NorCal. Ensemble solutions support drier ridging solution of GFS through midweek.
Some light overrunning precipitation advertised by NBM over Shasta County Thursday into Friday.
Otherwise dry through the extended with a cooling trend. High temperatures of 5 to 10 degrees above normal Tuesday, cool to near normal by Friday.