A cold and snowy pattern setting up over the western United States this week could reach Maryland on Sunday, in time for the Ravens/Vikings game at M&T Bank Stadium.

It appears what form the precipitation falls in could be a game-time decision, however, with a tricky line between liquid and frozen precipitation over the Baltimore area.

The National Weather Service had been forecasting a 60-70 percent chance of snow and sleet Sunday in Baltimore as of Tuesday morning, but by the evening, it had shifted the forecast to all rain. Air temperatures are forecast in the mid- to upper-30s.

Further north and west of the city, a wintry mix of precipitation was expected.

According to AccuWeather.com's Henry Margusity, a "trough" of cold air spilling southward across the western part of the country could shift eastward and stall around the lower Mississippi Valley and Tennessee Valley, potentially trying to send some snowy systems northeast into the mid-Atlantic.

Local meteorologist "Eric the Red" suggests a cold front pushing through the region Friday, bringing rain late in the week, could stall south of Maryland and disturbances come up from the Southeast bringing possible sleet and snow. Warm air in the atmosphere could change the precipitation to freezing rain and cold rain, potentially lasting through Sunday night, Eric says.

WBAL-TV's Tony Pann writes on his Facebook page: "IF, and that’s a big IF, the sky can clear Sat Night and the temps can dip below 32 by Sunday Morning...there could be a brief period of Freezing Rain. However, for various reasons, I do not see a major ice event at this time."

WMAR-TV's Mike Masco calls it a "rather complex situation" with a battle between rain and ice.

Three inches is the average snowfall in Baltimore in December. Six out of the past ten years have fallen below that average, though the decade also includes 20.1 inches in December 2009, the start of that record-setting season.