A deep trough across the southwestern U.S. in the early morning of Saturday, December 28 pushed eastward through the day, allowing low pressure to organize near the Oklahoma and Texas Panhandles.  The storm intensified as it moved into eastern Nebraska and western Iowa by 0600CST December 29.  Strong warming aloft ahead of the system led to periods of light rain or light mixed precipitation, while heavy snow organized in the trowal over central and northeast South Dakota.
Impacts from the storm became significant as the storm closed off in the mid-levels and slowed movement, only reaching southern Minnesota by 0600CST December 30.  Precipitation changed over to snow as colder air collapsed southward, and winds increased to a gusty 40 to 55 mph across southeast South Dakota and adjacent areas.  Snowfall totals ranged from 10 to 18 inches from the James River Valley westward, to 1 to 3 inches across much of northwest Iowa.  The storm resulted in record daily precipitation for Sioux Falls (0.40 inches on December 28 and 0.69 inches on December 29), as well as record daily precipitation (0.64 inches) and snowfall (7.0 inches) for Huron on December 28.
In total, South Dakota State Patrol reported 49 injury accidents and 44 slide-ins across southeast South Dakota during the episode.

Winter Weather in LINCOLN, SOUTH DAKOTA
From 28-DEC-19 02:00:00 to 30-DEC-19 08:00:00 (CST-6)
Reported by: COOP Observer

Light mixed precipitation resulted in a minor glaze of ice accumulation on December 28 before temperatures climbed above freezing. Snowfall developed early on December 29, and continued into December 30 producing hazardous travel. Snowfall totaled 3.8 inches at Canton and near 4 inches in southern Sioux Falls. Wind gusts reached as high as 46 mph near Davis on Monday, December 30, resulting in blowing and drifting snow.

Blizzard in DAVISON, SOUTH DAKOTA
From 28-DEC-19 22:00:00 to 30-DEC-19 00:00:00 (CST-6)
Reported by: COOP Observer

With surface temperatures hovering near freezing, light mixed precipitation resulted in a minor glaze of ice accumulation on December 28 and early December 29. Snowfall developed early on December 29, and continued heavy at times into December 30. Winds gusted as high as 49 mph at Mitchell after 1200CST December 29, resulting in white out conditions at times into early evening with travel not recommended. Interstate 90 was closed west of Mitchell from 1900CST December 28 until 1100CST December 30. Snowfall totaled 15.0 inches at Mitchell. Snow drifts to several feet were common. On December 30, the opening of state offices was delayed until 1300CST.

Winter Weather in YANKTON, SOUTH DAKOTA
From 29-DEC-19 08:00:00 to 30-DEC-19 12:00:00 (CST-6)
Reported by: COOP Observer

Light mixed precipitation changed quickly to snow early on December 29, and continued into December 30 producing hazardous travel. Snowfall totaled 5.0 inches at Yankton and 1.5 inches near Gayville. Wind gusts reached as high as 47 mph at Yankton by late Sunday, December 29, resulting in blowing and drifting snow.

Blizzard in HANSON, SOUTH DAKOTA
From 28-DEC-19 22:00:00 to 30-DEC-19 00:00:00 (CST-6)
Reported by: COOP Observer

With surface temperatures hovering near freezing, light mixed precipitation resulted in a minor glaze of ice accumulation on December 28 and early December 29. Snowfall developed early on December 29, and continued heavy at times into December 30. Winds gusted as high as 48 mph near Alexandria after 1200CST December 29, resulting in white out conditions at times into early evening with travel not recommended. Snowfall totaled 14.0 inches at Alexandria. On December 30, the opening of state offices was delayed until 1300CST.

Winter Weather in CLAY, SOUTH DAKOTA
From 29-DEC-19 08:00:00 to 30-DEC-19 10:00:00 (CST-6)
Reported by: COOP Observer

Light mixed precipitation changed quickly to snow early on December 29, and continued into December 30 producing hazardous travel. Snowfall totaled 4.0 inches 6 miles southeast of Centerville and 1.5 inches at Vermillion. Wind gusts reached as high as 37 mph 6 miles southeast of Centerville by late Sunday, December 29, resulting in blowing and drifting snow.

Blizzard in HUTCHINSON, SOUTH DAKOTA
From 29-DEC-19 02:00:00 to 30-DEC-19 00:00:00 (CST-6)
Reported by: COOP Observer

With surface temperatures hovering near freezing, light mixed precipitation resulted in a minor glaze of ice accumulation on December 28 and early December 29. Snowfall developed early on December 29, and continued heavy at times into December 30. Winds gusted as high as 47 mph near Freeman, 45 mph near Tripp and 37 mph at Parkston after 1200CST December 29, resulting in white out conditions at times into early evening with travel not recommended. Snowfall totaled 9.0 inches at Parkston and Menno, and 7.3 inches 11 miles south of Emery. On December 30, the opening of state offices was delayed until 1300CST.

Winter Weather in UNION, SOUTH DAKOTA
From 29-DEC-19 08:00:00 to 30-DEC-19 10:00:00 (CST-6)
Reported by: Department of Highways

Light mixed precipitation changed quickly to snow early on December 29, and continued into December 30 producing hazardous travel. Snowfall totaled 0.9 inches 6 miles north northeast of Elk Point. Wind gusts reached as high as 46 mph near Beresford and 40 mph in North Sioux City by late Sunday, December 29, resulting in blowing and drifting snow.

Blizzard in BEADLE, SOUTH DAKOTA
From 28-DEC-19 02:00:00 to 30-DEC-19 00:00:00 (CST-6)
Reported by: Official NWS Observations

With surface temperatures hovering near freezing, light mixed precipitation resulted in a minor glaze of ice accumulation on December 28. Snowfall developed early on December 29, and continued heavy at times into December 30. Winds gusted as high as 53 mph at Huron, 46 mph at Cavour and 45 mph near Wolsey after 1100CST December 29, resulting in white out conditions at times into early evening with travel not recommended. Snowfall totaled 9.0 inches at Huron and 8.0 inches 2 miles southeast of Wessington. Snow drifts to several feet were common. On December 30, the opening of state offices was delayed until 1300CST.

Blizzard in KINGSBURY, SOUTH DAKOTA
From 29-DEC-19 02:00:00 to 30-DEC-19 00:00:00 (CST-6)
Reported by: COOP Observer

With surface temperatures hovering near freezing, light mixed precipitation resulted in a minor glaze of ice accumulation on December 28 and early December 29. Snowfall developed early on December 29, and continued heavy at times into December 30. Winds gusted as high as 46 mph at Cavour and 45 mph at Arlington after 1200CST December 29, resulting in white out conditions at times into early evening with travel not recommended. Snowfall totaled 13.0 inches at De Smet and 11.4 inches at Iroquois.  On December 30, the opening of state offices was delayed until 1300CST.

Winter Storm in BROOKINGS, SOUTH DAKOTA
From 28-DEC-19 01:00:00 to 30-DEC-19 07:00:00 (CST-6)
Reported by: COOP Observer

With surface temperatures hovering near freezing, light mixed precipitation resulted in a minor glaze of ice accumulation on December 28 and early December 29.  Snowfall developed early on December 29, and continued heavy at times into December 30.  Travel became extremely hazardous by the morning of December 29 due to heavy snowfall. Snowfall totaled 11.5 inches 5 miles west of Bruce, 9.0 inches 1 miles southwest of Brookings, 8.5 inches near White, and 8.0 inches 2 miles northeast of Brookings. Wind gusts reached as high as 36 mph at Brookings on Monday, December 30, resulting in considerable blowing and drifting snow.  On December 30, South Dakota State University was closed, and the opening of state offices was delayed until 1300CST.

Blizzard in JERAULD, SOUTH DAKOTA
From 28-DEC-19 10:00:00 to 30-DEC-19 00:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

With surface temperatures hovering near freezing, light mixed precipitation resulted in a minor glaze of ice accumulation on December 28. Snowfall developed early on December 29, and continued heavy at times into December 30. Winds gusted as high as 46 mph at Wessington Springs after 1100CST December 29, resulting in white out conditions at times into early evening with travel not recommended. Snowfall totaled 12.0 inches at Wessington Springs. Snow drifts to several feet were common. On December 30, the opening of state offices was delayed until 1300CST.

Winter Storm in LAKE, SOUTH DAKOTA
From 28-DEC-19 01:00:00 to 30-DEC-19 10:00:00 (CST-6)
Reported by: COOP Observer

With surface temperatures hovering near freezing, light mixed precipitation resulted in a minor glaze of ice accumulation on December 28 and early December 29. Snowfall developed early on December 29, and continued heavy at times into December 30. Travel became extremely hazardous by the morning of December 29 due to heavy snowfall. Snowfall totaled 10.0 inches 2 miles south of Winfred, 8.0 inches near Madison, and 6.5 inches 2 miles north of Chester. Wind gusts reached as high as 41 mph at Brookings on Monday, December 30, resulting in considerable blowing and drifting snow. On December 30, the opening of state offices was delayed until 1300CST, and Dakota State University was closed.

Blizzard in SANBORN, SOUTH DAKOTA
From 28-DEC-19 10:00:00 to 30-DEC-19 00:00:00 (CST-6)
Reported by: COOP Observer

With surface temperatures hovering near freezing, light mixed precipitation resulted in a minor glaze of ice accumulation on December 28 and early December 29. Snowfall developed early on December 29, and continued heavy at times into December 30. Winds gusted as high as 50 mph near Forestburg after 1100CST December 29, resulting in white out conditions at times into early evening with travel not recommended. Snowfall totaled 12.5 inches 4 miles north northeast of Forestburg. Snow drifts to several feet were common. On December 30, the opening of state offices was delayed until 1300CST.

Winter Storm in MCCOOK, SOUTH DAKOTA
From 28-DEC-19 22:00:00 to 30-DEC-19 09:00:00 (CST-6)
Reported by: COOP Observer

With surface temperatures hovering near freezing, light mixed precipitation resulted in a minor glaze of ice accumulation on December 28 and early December 29. Snowfall developed early on December 29, and continued heavy at times into December 30. Travel became extremely hazardous by the morning of December 29 due to heavy snowfall. Snowfall totaled 8.0 inches at Bridgewater and 6.0 inches 6 miles northwest of Montrose. Wind gusts reached as high as 51 mph near Montrose early on Monday, December 30, resulting in considerable blowing and drifting snow. On December 30, the opening of state offices was delayed until 1300CST.

Blizzard in MINER, SOUTH DAKOTA
From 28-DEC-19 22:00:00 to 30-DEC-19 00:00:00 (CST-6)
Reported by: COOP Observer

With surface temperatures hovering near freezing, light mixed precipitation resulted in a minor glaze of ice accumulation on December 28 and early December 29. Snowfall developed early on December 29, and continued heavy at times into December 30. Winds gusted as high as 50 mph near Forestburg and 41 mph at Madison after 1200CST December 29, resulting in white out conditions at times into early evening with travel not recommended. Snowfall totaled 12.0 inches at Howard. On December 30, the opening of state offices was delayed until 1300CST.

Winter Weather in MOODY, SOUTH DAKOTA
From 28-DEC-19 01:00:00 to 30-DEC-19 08:00:00 (CST-6)
Reported by: COOP Observer

Light mixed precipitation resulted in a minor glaze of ice accumulation on December 28 before temperatures climbed above freezing. Snowfall developed early on December 29, and continued into December 30 producing very hazardous travel. Snowfall totaled 5.0 inches 11 miles north of Colman and 3.7 inches at Flandreau. Wind gusts reached as high as 38 mph near Ward on Monday, December 30, resulting in considerable blowing and drifting snow.

Blizzard in AURORA, SOUTH DAKOTA
From 28-DEC-19 15:00:00 to 30-DEC-19 00:00:00 (CST-6)
Reported by: COOP Observer

With surface temperatures hovering near freezing, light mixed precipitation resulted in a minor glaze of ice accumulation on December 28 and early December 29. Snowfall developed early on December 29, and continued heavy at times into December 30. Winds gusted as high as 51 mph at Plankinton and 44 mph at White Lake after 1000CST December 29, resulting in white out conditions at times into early evening with travel not recommended. Interstate 90 was closed west of Mitchell from 1900CST December 28 until 1100CST December 30. Snowfall totaled 11.0 inches 4 miles west of Stickney and 8.7 inches at White Lake. Snow drifts to several feet were common. On December 30, the opening of state offices was delayed until 1300CST.

Winter Weather in MINNEHAHA, SOUTH DAKOTA
From 28-DEC-19 02:00:00 to 30-DEC-19 08:00:00 (CST-6)
Reported by: Official NWS Observations

Light mixed precipitation resulted in a minor glaze of ice accumulation on December 28 before temperatures climbed above freezing. Snowfall developed early on December 29, and continued into December 30 producing hazardous travel. Snowfall totaled from 4 to 6 inches around the Sioux Falls metro area, with 4.0 inches at the NWS office. Wind gusts reached as high as 44 mph near Dell Rapids and 41 mph at Sioux Falls on Monday, December 30, resulting in blowing and drifting snow.

Blizzard in GREGORY, SOUTH DAKOTA
From 28-DEC-19 12:00:00 to 30-DEC-19 00:00:00 (CST-6)
Reported by: COOP Observer

Snowfall developed early afternoon on December 28, and continued heavy at times into early December 30. Winds gusted as high as 44 mph 3 miles west of Geddes after 1500CST December 29, resulting in considerable blowing and drifting snow with travel not recommended. Snowfall totaled an impressive 16.0 inches 4 miles south southwest of Pickstown and also 8 miles south of Herrick, 14.5 inches 10 miles south southeast of Burke, 13.5 inches at Gregory and 13.0 inches 4 miles southwest of Burke. Snow drifts to several feet were common. On December 30, the opening of state offices was delayed until 1300CST.

Winter Weather in TURNER, SOUTH DAKOTA
From 28-DEC-19 02:00:00 to 30-DEC-19 09:00:00 (CST-6)
Reported by: COOP Observer

Light mixed precipitation resulted in a minor glaze of ice accumulation on December 28 before temperatures climbed above freezing. Snowfall developed early on December 29, and continued into December 30 producing hazardous travel. Snowfall totaled 7.5 inches at Marion 5.0 inches 7 miles west southwest of Parker and 3.8 inches at Hurley.  Wind gusts reached as high as 47 mph near Freeman and 46 mph near Davis on Monday, December 30, resulting in blowing and drifting snow.

Blizzard in BRULE, SOUTH DAKOTA
From 28-DEC-19 14:00:00 to 30-DEC-19 00:00:00 (CST-6)
Reported by: COOP Observer

With surface temperatures hovering near freezing, light mixed precipitation resulted in a minor glaze of ice accumulation early afternoon on December 28. Snowfall developed mid-afternoon on December 28, and continued heavy at times into early December 30. Winds gusted as high as 47 mph at Chamberlain after 1700CST December 29, resulting in considerable blowing and drifting snow with travel not recommended. Interstate 90 was closed west of Mitchell from 1900CST December 28 until 1100CST December 30. Snowfall totaled 8.4 inches at Chamberlain and 8.0 inches 5 miles south southwest of Chamberlain. Snow drifts to several feet were common. On December 30, the opening of state offices was delayed until 1300CST.

Blizzard in CHARLES MIX, SOUTH DAKOTA
From 28-DEC-19 16:00:00 to 30-DEC-19 00:00:00 (CST-6)
Reported by: COOP Observer

After a brief wintry mix early on December 28 which produced a brief glaze of icing, snowfall developed early afternoon on December 28, and continued heavy at times into early December 30. Winds gusted as high as 44 mph 3 miles west of Geddes and also at Wagner after 1500CST December 29, resulting in considerable blowing and drifting snow with travel not recommended. Snowfall totaled an impressive 16.0 inches 2 miles north of Lake Andes, 15.5 inches near Wagner, 15.0 inches 3 miles south of Dante, 12.5 inches at Platte, and 11.0 inches 2 miles northeast of Academy. Snow drifts to several feet were common. On December 30, the opening of state offices was delayed until 1300CST.

Blizzard in BON HOMME, SOUTH DAKOTA
From 28-DEC-19 20:00:00 to 30-DEC-19 00:00:00 (CST-6)
Reported by: COOP Observer

After a brief wintry mix early on December 28 which produced a brief glaze of icing, snowfall developed late evening on December 28, and continued heavy at times into early December 30. Winds gusted as high as 47 mph at Tyndall after 1500CST December 29, resulting in considerable blowing and drifting snow with travel not recommended. Snowfall totaled 11.0 inches 8 miles west of Springfield and 6.6 inches at Tyndall. Snow drifts to several feet were common. On December 30, the opening of state offices was delayed until 1300CST.

Blizzard in DOUGLAS, SOUTH DAKOTA
From 28-DEC-19 17:00:00 to 30-DEC-19 00:00:00 (CST-6)
Reported by: CoCoRaHS

Warmer air produced a period of light rain or wintry mix through early afternoon December 28, which produced a brief glaze of icing. Snowfall developed early evening December 28, and continued heavy at times into early December 30. Winds gusted as high as 44 mph at Wagner and 39 mph at Parkston after 1200CST December 29, resulting in considerable blowing and drifting snow with travel not recommended. Snowfall totaled an impressive 15.8 inches 2 miles south of Armour, 15.5 inches 5 miles west of Armour and 8.2 inches 10 miles west of Dimock. Snow drifts to several feet were common. On December 30, the opening of state offices was delayed until 1300CST.