Snow, including some heavy snow showers, is in the forecast into sometime Wednesday from what the National Weather Service describes as a “potent storm.”

The cold-weather shelter at the Harambee Center in downtown Renton has been activated for Monday and Tuesday to provide shelter for those in need.

The heavy snow showers will start over Western Washington Monday afternoon, after a brief break Monday morning. Tuesday and Wednesday, snow could accumulate to several inches in the lowlands, but where is uncertain.

“A potent Pacific will impact all of Western Washington late Tuesday night and Wednesday,” according to a weather service, which has issued a winter storm watch for the region. Such a watch means there is the potential for severe winter weather.

The storm could bring “significant snowfall amounts” to the mountains and lowlands, with power outages and hazardous driving conditions, according to the weather service.

When the snow will turn to rain is also uncertain.

The State Route 520 bridge was reopened Monday morning after a weekend-long closure fpr construction.

Here’s the forecast for Renton as of Monday morning:

M.L.King Day: Snow showers likely, mainly between 10 a.m. and 4 p.m.. Patchy freezing fog before 10 a.m. Cloudy, with a high near 37. South wind between 8 and 14 mph. Chance of precipitation is 70 percent. Total daytime snow accumulation of less than a half inch possible.

Monday night: Snow showers, mainly after 10 p.m. Low around 31. South southwest wind between 6 and 11 mph. Chance of precipitation is 90 percent. New snow accumulation of 1 to 2 inches possible.

Tuesday: Snow showers. High near 36. Southwest wind between 8 and 11 mph. Chance of precipitation is 80 percent. New snow accumulation of 1 to 3 inches possible.

Tuesday Night: Snow. Low around 28. West wind 5 to 7 mph becoming north northeast. Chance of precipitation is 80 percent. New snow accumulation of 1 to 2 inches possible.

Wednesday: Snow. High near 37. Northeast wind between 6 and 11 mph. Chance of precipitation is 100 percent. New snow accumulation of 2 to 4 inches possible.

Wednesday Night: Rain. Low around 37. Breezy. Chance of precipitation is 100%.

Thursday: Rain. High near 47. Chance of precipitation is 100%.

Washington State Department of Transportation maintenance crews were out in full force on Sunday afternoon and evening sanding roads and helping Washington State Patrol troopers handle multiple collision and lane closures, according to a department news release.

“Our biggest problem is people who drive too fast for conditions. They lose control, leave the roadway or strike other vehicles,” said Trooper Julie Startup.

 “Maintenance crews are keeping a close eye on the changing weather and have plows and sanders stocked and ready,” said Chris Christopher, director of Maintenance Operations for WSDOT. “But we really need drivers’ help to plan their route. If you travel, be ready for snow and ice even if the sun’s out in your neighborhood. The conditions could change rapidly and the conditions you see out your window could be dramatically different 10 miles down the road.”

 Drivers can prepare for snow and ice by checking travel and roadway conditions the WSDOT website and packing their winter weather supplies, including tire chains.