Sunday, March 5, 2017

Except for a storm this weekend, dry weather will persist over much of California into the middle of March; then, another big storm will bring more rain/snow

Storm break for California to offer relief from flooding, mudslides into mid-March
By Alex Sosnowski, AccuWeather senior meteorologist
March 04, 2017, 1:56:42 PM EST

Except for a storm this weekend, dry weather will persist over much of California into the middle of March.

Heavy snow and high winds can impede travel over Donner Pass along Interstate 80 for a time this weekend. However, for much of Southern California, the only day where there may be some rain will be on Sunday.

"Some rain will move through Los Angeles, San Bernardino and San Diego on Sunday," according to AccuWeather Senior Meteorologist Ken Clark. "While this will not be a big storm, enough rain will fall to make streets slick."

The storm will produce periods of rain in Central and Northern California, for cities such as San Francisco, Sacramento and Redding. The rain will raise stream, river and reservoir levels once again.

"Any flooding that occurs in Northern California will pale in comparison to that of other storms this winter," Clark said.

Enough rain can fall to hinder repairs on the Oroville Dam Spillway, north of Sacramento, California, temporarily.

"The storm will also kick up strong wind gusts of 50-60 mph from the upper deserts of California and northern Arizona to Utah and Wyoming," AccuWeather Senior Meteorologist Kristina Pydynowski said. "This includes in Las Vegas, Nevada; St. George, Utah; and Flagstaff, Arizona."

"These winds could lead to tree damage, power outages and dangerous crosswinds for high-profile vehicles. Blowing dust could also get kicked up in the deserts."

Outside of the storm this weekend, the vast majority of the state will be free from rain into next weekend.

"Most storms will take an path across the northwestern United States through next week," according to AccuWeather Lead Long-Range Meteorologist Paul Pastelok.

It's normal for the amount of rain and mountain snow to begin to diminish across California during March. For example, in San Bernardino, average rainfall during February, March and April is 2.50 inches, 1.00 inch and 0.25 of an inch respectively.

"We have to watch for another big storm, around March 15-17, that may roll in from the Pacific over Central California," according to AccuWeather Lead Long-Range Meteorologist Paul Pastelok.

From Dec. 1 to Feb. 28, rainfall over much of the state has been 150 to 200 percent of average. In the Sierra Nevada, the amount of precipitation has been 200 to 400 percent of average (2x to 4x of average).

In lieu of a big, warm storm, much of the snowpack in the Sierra Nevada will be released during the spring and summer as the seasonal thaw progresses to higher elevations.

However, any time there is an excessive amount of snow on the ground and a storm comes along with heavy rain and warmth, there is a risk of flooding.

"Other than the ongoing benefits from the storms, the flooding risk will remain a concern moving forward over the next couple of months before the dry season takes hold," Pastelok said.

The northern half of California is no longer in the grips of a drought nor is it abnormally dry, according to the United States Drought Monitor. About 25 percent of the state, all in the southern half, remains in some sort of long-term dryness.The area of severe long-term drought has shrunk to about 4 percent of the state, compared to 83 percent one year ago. The areas where long-term drought lingers encompasses parts of Imperial, Los Angeles, Ventura and Santa Barbara counties