A colossal late winter storm began to develop early in the morning of March 13, with intense low pressure across southeast Colorado by 0600CST.  A surge of warm air ahead of this system resulted in bands of widespread liquid precipitation, along with scattered thunderstorms developing through the day on the 13th, and continuing as a stacked cyclone moved into western Iowa by 0600CST March 14.
Rain, with some areas of freezing rain resulting in around a tenth of an inch ice accumulation around Huron and Chamberlain, started to change to snow very late on March 13 into the early hours of the 14th.  As winds increased to 30 to 40 mph with gusts to 55 to 65 mph, whiteout conditions developed from the James River westward during the brief window of snowfall despite a limited accumulation of new snow (generally less than 2 inches) and widespread rainfall over the existing snow cover.
In addition, with the ground largely frozen to depths of 10 to 20 inches, antecedent snow cover with as much as 4 to 6 inches of liquid water equivalent, and the rapid warming of the air mass and resulting widespread rainfall from 1 to 3 inches, major flooding resulted across the region.
Record precipitation on March 13 included, but was not limited to De Smet (1.90 inches), Vermillion (1.55 inches), Platte (1.86 inches), Gregory (1.26 inches), Mitchell (1.82 inches), Huron (1.43 inches), Primghar (1.98 inches), Menno (1.81 inches), Sioux City (1.63 inches), and Sioux Falls (1.91 inches).
Peak wind gusts of 58 mph or higher for the storm included: 67 mph at Mitchell, 65 mph 5 miles west of Geddes, 63 mph at Huron, 61 mph at Spencer, 60 mph at Sioux Falls, Jackson, and 2 miles west of Dovray, 59 mph at Gregory, Madison and Marshall, and 58 mph at Chamberlain, near Beaver Creek, and Sioux City.

Blizzard in BRULE, SOUTH DAKOTA
From 14-MAR-19 07:00:00 to 14-MAR-19 13:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

After an appreciable amount of rainfall and some light freezing rain resulting in up to a tenth of an inch ice accumulation, precipitation changed to snow after 1800CST March 13.  As northwest winds increased and frequent gusts topped 45 mph, periods of whiteout conditions developed during the morning hours on March 14 with travel not advised across the county.  Snowfall accumulated to 4.2 inches 8 miles south southwest of Chamberlain, 2.8 inches at Chamberlain and 2.5 inches near Pukwana.

Blizzard in DOUGLAS, SOUTH DAKOTA
From 14-MAR-19 07:00:00 to 14-MAR-19 13:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

After an appreciable amount of rainfall and some light freezing rain resulting in up to a tenth of an inch ice accumulation, precipitation changed to snow after 0200CST March 14.  As northwest winds increased and frequent gusts topped 45 mph, periods of whiteout conditions developed during the morning hours on March 14 with travel not advised across the county.  Snowfall accumulated to 0.7 inches at Armour.

Blizzard in SANBORN, SOUTH DAKOTA
From 14-MAR-19 06:00:00 to 14-MAR-19 13:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

After an appreciable amount of rainfall and some light freezing rain resulting in up to a tenth of an inch ice accumulation, precipitation changed to snow after 0000CST March 14.  As northwest winds increased and frequent gusts topped 45 mph, periods of whiteout conditions developed during the morning hours on March 14 with travel not advised across the county.  Snowfall accumulated to 1.0 inches 4 miles north northeast of Forestburg.

Blizzard in GREGORY, SOUTH DAKOTA
From 14-MAR-19 06:00:00 to 14-MAR-19 13:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

After an appreciable amount of rainfall and some light freezing rain resulting in up to a tenth of an inch ice accumulation, precipitation changed to snow after 1800CST March 13.  As northwest winds increased and frequent gusts topped 45 mph, periods of whiteout conditions developed during the morning hours on March 14 with travel not advised across the county.  Snowfall accumulated to 3.0 inches 9 miles south of Dallas and 2.0 inches at Gregory.

Blizzard in JERAULD, SOUTH DAKOTA
From 14-MAR-19 06:00:00 to 14-MAR-19 13:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

After an appreciable amount of rainfall and some light freezing rain resulting in up to a tenth of an inch ice accumulation, precipitation changed to snow after 1800CST March 13.  As northwest winds increased and frequent gusts topped 45 mph, periods of whiteout conditions developed during the morning hours on March 14 with travel not advised across the county.  Snowfall accumulated to 2.0 inches at Wessington Springs.

Blizzard in AURORA, SOUTH DAKOTA
From 14-MAR-19 06:00:00 to 14-MAR-19 13:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

After an appreciable amount of rainfall and some light freezing rain resulting in up to a tenth of an inch ice accumulation, precipitation changed to snow after 0000CST March 14.  As northwest winds increased and frequent gusts topped 45 mph, periods of whiteout conditions developed during the morning hours on March 14 with travel not advised across the county.  Snowfall accumulated to 0.8 inches at White Lake.

Blizzard in CHARLES MIX, SOUTH DAKOTA
From 14-MAR-19 06:00:00 to 14-MAR-19 13:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

After an appreciable amount of rainfall and some light freezing rain resulting in up to a tenth of an inch ice accumulation, precipitation changed to snow after 0000CST March 14.  As northwest winds increased and frequent gusts topped 45 mph, periods of whiteout conditions developed during the morning hours on March 14 with travel not advised across the county.  Snowfall accumulated to 0.9 inches at Geddes.

Blizzard in BEADLE, SOUTH DAKOTA
From 14-MAR-19 06:00:00 to 14-MAR-19 13:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

After an appreciable amount of rainfall and some light freezing rain resulting in up to a tenth of an inch ice accumulation, precipitation changed to snow after 2200CST March 13.  As northwest winds increased and frequent gusts topped 45 mph, periods of whiteout conditions developed during the morning hours on March 14 with travel not advised across the county.  Snowfall accumulated to 2.5 inches 2 miles southeast of Wessington and 2.2 inches at Huron.