Associated Press - December 26, 2009 8:44 PM ET

SIOUX CITY, Iowa (AP) - Storms have dumped more than 20 inches of snow on parts of western Iowa over the last four days, and forecasters say hazardous conditions will linger with the snow.

The National Weather Service says 20.7 inches of snow had fallen in Sioux City as of Saturday afternoon.

2 of the blizzard's four days - on Wednesday and Friday - also broke snow records in Sioux City.

The weather service is warning drivers to beware of drifting and blowing snow as winds of up to 35 mph whip across the area. Visibility is expected to drop to a half-mile in some open areas.

Many roads have already been closed, including Interstate 90 from Wyoming to Sioux Falls, S.D.

Eastern Iowa was largely spared heavy snowfall, with no more than two to six inches.

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