It was a chilly 38 degrees in Berkeley on Friday morning, but the cold snap is nothing compared to what is coming.

Weather forecasters are predicting that mammoth amounts of rain will fall in the Bay Area this weekend. From Saturday to Monday, urban areas could see as much as 2.5 to 4.5 inches of rain, according to Charles Bell of the National Weather Service. The hilly areas could see from 5-9 inches. It will be windy, too, with gusts in the hills rising to 50 mph, which may knock down trees and power lines, said Bell.

The heavy rainfall is due to an “atmospheric river” that is funneling moist air laden with rain and snow into California, according to the California Weather Blog. The river is wide enough that large parts of California, from the Oregon border to Los Angeles, will be affected.

“Since this system is expected to be slow-moving, the associated atmospheric river may stall over some portion of northern or central California on Sunday or Monday — or even waver back northward temporarily,” according to the California Weather Blog. “If and when this occurs, there may be a 100-200 mile wide band of even higher precipitation totals. It’s impossible to say at this time where any stalling or frontal waves might occur, but that has the potential to be a serious situation locally.”

PG&E is revving up for the storm by sending out crews to trim tree limbs that are close to power lines, said Andrea Menniti, a spokeswoman for the utility. Friday, crews were trimming trees on Henry Street near Rose Avenue, she said. A local vegetation management team identifies which limbs are precariously close to power lines, she said.

PG&E is also planning to open its emergency centers this weekend so as to be able to respond to power outages quickly, said Menniti. It is an “all-hands-on-deck” kind of weekend, she said.

“With storms bearing down on our region, we want our customers to know that PG&E is prepared, that we’re mobilizing resources and that we will work around the clock to restore service to customers,” Pat Hogan, PG&E’s senior vice president of electric transmission and distribution said in a press release. “Likewise, we encourage our customers to have a personal or family preparedness plan in place and – above all else – stay safe.”

PG&E has an online outage map, too.

The city of Berkeley has also prepared for cold, wet weather. In the past few weeks, after the city activated an Emergency Operations Center to focus resources on those without shelter, the city has greatly expanded its shelter capacity. It can now offer shelter to 380 individuals a night, according to city reports.

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The city opened a new emergency shelter on Dec. 23 at 1231 Second St. Unlike the city’s other emergency shelters, this one allows people to bring their dogs, and also has bicycle parking and a greater area for storage, according to city spokesman Matthai Chakko. The new emergency shelter, which used to house public works employees, has two indoor bathrooms. The city is building an additional two bathrooms outside, one of which is ADA-accessible, he said.

The new emergency shelter can accommodate about 45 people and it has been very well used since it opened, said Chakko. Berkeley runs three other emergency shelters: at the North Berkeley Senior Center, the Frances Albrier Community Center and at the First Presbyterian Church. Each of those shelters can accommodate 65 people. These beds are in addition to the 140 shelter beds Berkeley provides through contracts with community agencies.

The emergency shelters are opened when there is a 30% or more chance of rain, or when temperatures drop below 40 degrees.

Berkeley has also contracted to open places during the day where those without homes can seek shelter from the elements. The Multi-Agency Service Center in the Veterans’ Building, at 1931 Center St., is now open from 8 a.m. to 4:45 p.m. (Previously it shut at noon.) Berkeley Food & Housing has opened a space in the same building that will be open from 4:45 p.m. until 6:30 p.m. Most overnight shelters open around 7 p.m., although those hours can be pushed back in the public buildings if events are going on, said Chakko.

On Friday, Berkeley officials rousted the homeless encampment set up in the Gourmet Ghetto at Spruce and Rose streets by the group First They Came for the Homeless, according to the group’s Facebook post.

A number of homeless individuals have been preparing for the wet weather by buying tarps, according to Quentin Moore, the manager of Berkeley Ace Hardware on Milvia Street. The store has also seen an uptick in the sale of utility pumps and sandbags, he said. Moore expects sales of these and other emergency items to increase as the rains begin.

Berkeley is also handing out sandbags at the City Corporation Yard on 1326 Allston Way, Mon – Fri, 8:00 a.m. to 4:00 p.m. Residents must show I.D.

“City staff will be available to deal with downed trees or flooding affecting local homes, businesses or streets. In an emergency, they can be reached by dialing 311 on a mobile phone or landline. If outside the city, call 981-2489. Crews will be dispatched and respond as quickly as possible.”

City officials warn not to touch damaged power lines or electrical equipment, and to call 911 immediately. Then they should notify PG&E at 1-800-743-5002.

For more tips from the city of Berkeley, click here.

Alameda County Public Works will be posting updates here. Nixle alert users can sign up at acalert.org.

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Frances Dinkelspiel is co-founder and executive editor of Berkeleyside.