Sierra braces for blizzard conditions; 4 feet of snow, possibility of thundersnow

SAN FRANCISCO -- A storm front advancing toward the Bay Area Sunday morning, triggered winter weather warnings, advisories and special weather statements for the havoc it will churn up in the Sierra over the next several days. 

The National Weather Service said the first punch late Sunday, early Monday morning may be the most potent.

"The most intense snowfall rates are most likely for early-mid morning Monday  -- up to 3 inches/hour with possible embedded lightning -- and from late morning through the evening on Tuesday -- 1-2 inches/hour," the weather forecasters at the NWS office in Reno predicted.

The forecast was a welcomed relief to the Sierra ski resort operators who struggled late last season. After the front rolls through it will leave behind cold temperatures to, allowing the snow making machines to kick into full gear with the hopes of a strong Thanksgiving weekend rise in skiers.

"The majority of the guidance shows the storm finally exiting to the east on Wednesday, leaving behind lingering snow showers and  plenty of cold air," forecasters said. "While highs Wednesday and Thursday will struggle to reach the lower 30s near the Sierra, it will really be felt Wednesday and Thursday nights when less cloud cover and light winds are expected."

"Lows in the single digits and teens are likely in most areas, with sub-zero temperatures in the colder Sierra valleys--especially if  meaningful snow cover is present."

And what kind of snow totals may be left in the storm's wake.

"Total snow accumulations of 1 to 2 feet, except 2 to 4 feet above 7000 feet," the weather service predicted. "Winds gusting in the lower elevations as high as 55 mph and gusts above 100 mph along Sierra ridge lines Sunday evening into early Monday morning."

Travel in the Sierra is not advised, particularly  on I-80 and Highway 50 where chains will be needed.

"Travel could be very difficult to impossible," the weather service warned. "The hazardous conditions will impact commute times over mountain passes." 

Meanwhile, the storm front will deliver about an inch of rain to 3 inches in the higher elevations of the Bay Area.

"Forecasted rainfall totals for this system (now through Wednesday morning) is looking to be slightly higher than previously 
advertised, but roughly still about an inch across the region," forecasters said. "Higher elevations such as the Santa Cruz Mountains and the Santa Lucias/Big Sur could see  2-2.5 inches up to 3 inches."