A mid-level disturbance worked northeast from Colorado early morning January 12 into Iowa by late day.  Broad lift initially within the warm advection zone became increasingly concentrated, with deeper lift in the dendritic growth layer by afternoon across northwest Iowa.  Snowfall rates up to 1.5 to 2 inches per hour were noted across northwest Iowa and northeast Nebraska at the peak during the late afternoon.

Winter Storm in SIOUX, IOWA
From 12-JAN-20 09:00:00 to 12-JAN-20 20:00:00 (CST-6)
Reported by: COOP Observer

Initially light snowfall became heavy at times during the afternoon and early evening hours.  Intense snowfall rates resulted in a rapid worsening of road conditions. Accumulation reached 7.0 inches at Orange City, 6.5 inches at Alton and 4.0 inches at Sioux Center.

Winter Weather in LYON, IOWA
From 12-JAN-20 11:00:00 to 12-JAN-20 20:00:00 (CST-6)
Reported by: COOP Observer

Snowfall was briefly moderate to heavy during the afternoon, accumulating to 3.0 inches at Rock Rapids, resulting in dangerous travel conditions.

Winter Weather in OSCEOLA, IOWA
From 12-JAN-20 11:00:00 to 12-JAN-20 20:00:00 (CST-6)
Reported by: COOP Observer

Snowfall was briefly moderate to heavy during the afternoon and early evening, accumulating to 3.5 inches at Sibley, resulting in dangerous travel conditions.

Winter Weather in DICKINSON, IOWA
From 12-JAN-20 11:00:00 to 12-JAN-20 21:00:00 (CST-6)
Reported by: COOP Observer

Snowfall was briefly moderate to heavy during the afternoon and early evening, accumulating to 4.4 inches 4 miles northwest of Milford, 4.1 inches at Spirit Lake, 4.0 inches at Milford and 3.1 inches at Lake Park, resulting in dangerous travel conditions.

Winter Weather in CLAY, IOWA
From 12-JAN-20 10:00:00 to 12-JAN-20 21:00:00 (CST-6)
Reported by: COOP Observer

Snowfall was briefly moderate to heavy during the afternoon and early evening, accumulating to 4.5 inches 3 miles west northwest of Everly, 4.0 inches at Peterson and 3.9 inches at Spencer, resulting in dangerous travel conditions.

Winter Weather in O'BRIEN, IOWA
From 12-JAN-20 10:00:00 to 12-JAN-20 21:00:00 (CST-6)
Property damage: 11.00K
Reported by: COOP Observer

Snowfall was briefly moderate to heavy during the afternoon and early evening, accumulating to 5.3 inches at Hartley, 5.0 inches at Sanborn, 4.7 inches at Primghar and 3.6 inches at Sheldon, resulting in dangerous travel conditions.  Poor road conditions lingered after the snowfall due to continued drifting snow with increased southerly winds. On January 13 around 1620CST, a vehicle lost control attempting to pass another on U.S. Highway 18 around 2 miles east of Sanborn, entered the ditch and rolled, resulting in an (indirect) injury to the driver.  A second accident around 0900CST the following day and in approximately the same location resulted in a rollover in the ditch and another (indirect) injury. Property damage costs are rough estimates.

Winter Weather in PLYMOUTH, IOWA
From 12-JAN-20 14:00:00 to 12-JAN-20 20:00:00 (CST-6)
Reported by: COOP Observer

Snowfall was briefly moderate to heavy during the afternoon, accumulating to 3.5 inches at Le Mars and 3.0 inches at Brunsville and Akron, resulting in dangerous travel conditions.  Following this snowfall, slick road conditions which lingered due to drifting snow during the early morning of January 14 resulted in a pair of (indirect) fatalities in a two-vehicle accident on County Road K22 near Granite Avenue.