Snow was predicted to blanket Snohomish County today, but it might just be a warm-up for a bigger storm headed this way.

The National Weather Service in Seattle is monitoring another system that could develop into a full-blown winter storm by Tuesday, dumping more snow than the 1 to 3 inches that was predicted to fall in the lowlands by this morning, forecaster Dennis D’Amico said.

As of Saturday, meteorologists could not tell whether the incoming storm is more likely to bring rain or snow, he said.

“It has the potential to be a major winter storm,” D’Amico said.

Snohomish County officials do not plan to open the Snohomish County Emergency Operations Center until more information is available.

“They are always on standby if things get really bad, but at this point, they don’t see any circumstances necessitating that need,” county spokesman Christopher Schwarzen said.

About an inch of new snow was expected to fall in the Snohomish County lowlands later today, with the possibility of snow in the forecast Monday and Tuesday. A snow advisory issued by the national weather service was set to expire at 4 a.m. today.

Up to a foot of snow was forecast to fall in the north Cascades by early today. The National Weather Service issued heavy snow and avalanche warnings for the western slopes of the mountains.

Temperatures could remain in the mid-30s until mid-week, D’Amico said. Rain is forecast for Wednesday.

For the next few days, drivers should watch out for black ice on bridges, offramps and onramps, as well as on curves and shaded areas of roadways, said Roy Scalf, operations manager of road maintenance for the Snohomish County Public Works Department.

The ground is already cold from recent weather, and near-freezing temperatures during the next few days could keep snowfall from melting, Scalf said.

Work crews spread de-icer on county roads on Friday, and the county also has 20 plow and sander trucks on standby. The state Department of Transportation has also been sanding highways and freeways, with about 100 plows and de-icer trucks on standby, transportation spokesman Mike Murphy said.

“We’re more concerned at this point with ice, because we expect temperatures to dip and stay below freezing,” he said.

The city of Everett also has eight sand trucks, seven of which have plows, and two graders on standby, city spokeswoman Kate Reardon said.

If the roads are icy, commuters should either ride the bus or consider staying home for the day, Everett Fire Department Battalion Chief Steve Parker said.

“It helps us, because as soon as that white stuff comes down, people are sliding all over the place,” he said.

Reporter Scott Pesznecker: 425-339-3436 or spesznecker@heraldnet.com.