A strong upper-level wave and jet entrance region pushed into the Northern Plains, with a tight mid-level frontal boundary stalling across the area for several hours within confluent southwest flow aloft.  Unseasonably cold air rushed into the region behind a southward surging low-level frontal boundary,  with developing precipitation making a very rapid transition from rain to snow.  Snow accumulated quickly in the overnight and early morning hours due to proximity of slightly unstable air aloft.

Winter Weather in MCCOOK, SOUTH DAKOTA
From 14-OCT-18 02:00:00 to 14-OCT-18 07:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Light to occasionally moderate snow accumulated to 2 to 6 inches across portions of southeast South Dakota near and south of Interstate 90. Snowfall of 3.5 inches was measured 6 miles northwest of Montrose, with 3.1 inches at Montrose and 2.0 inches at Bridgewater and 5 miles northeast of Salem.

Winter Weather in LAKE, SOUTH DAKOTA
From 14-OCT-18 02:00:00 to 14-OCT-18 07:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Light to occasionally moderate snow accumulated to 2 to 6 inches across portions of southeast South Dakota near and south of Interstate 90. Snowfall of 2.6 inches was measured 2 miles north of Chester, with 1.2 inches 2 miles south of Winfred.

Winter Weather in CHARLES MIX, SOUTH DAKOTA
From 14-OCT-18 02:00:00 to 14-OCT-18 06:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Light to occasionally moderate snow accumulated to 2 to 6 inches across portions of southeast South Dakota near and south of Interstate 90. Snowfall of 3.0 inches was measured near Lake Andes, with 2.0 inches at Platte.

Winter Weather in BON HOMME, SOUTH DAKOTA
From 14-OCT-18 01:00:00 to 14-OCT-18 06:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Light to occasionally moderate snow accumulated to 2 to 6 inches across portions of southeast South Dakota near and south of Interstate 90. Snowfall of 3.0 inches was measured near 8 miles west of Springfield, with 2.0 inches at Tyndall.

Winter Weather in DAVISON, SOUTH DAKOTA
From 14-OCT-18 03:00:00 to 14-OCT-18 06:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Light to occasionally moderate snow accumulated to 2 to 6 inches across portions of southeast South Dakota near and south of Interstate 90. A daily record snowfall of 1.4 inches was measured at Mitchell. Following the snowfall, a record low maximum temperature (38) was established at Mitchell on the 14th, with a record low minimum temperature (24) on the 15th.

Winter Weather in HANSON, SOUTH DAKOTA
From 14-OCT-18 02:00:00 to 14-OCT-18 06:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Light to occasionally moderate snow accumulated to 2 to 6 inches across portions of southeast South Dakota near and south of Interstate 90. Snowfall of 2.0 inches was measured at Alexandria.

Winter Weather in TURNER, SOUTH DAKOTA
From 14-OCT-18 01:00:00 to 14-OCT-18 08:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

Light to occasionally moderate snow accumulated to 2 to 6 inches across portions of southeast South Dakota near and south of Interstate 90. Snowfall of 4.3 inches was measured near Hurley, with 4.3 inches near Davis and 3.0 inches 7 miles west southwest of Parker.

Winter Weather in CLAY, SOUTH DAKOTA
From 14-OCT-18 02:00:00 to 14-OCT-18 07:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Light to occasionally moderate snow accumulated to 2 to 6 inches across portions of southeast South Dakota near and south of Interstate 90. Snowfall of 2.0 inches was measured 6 miles southeast of Centerville.

Winter Weather in LINCOLN, SOUTH DAKOTA
From 14-OCT-18 01:00:00 to 14-OCT-18 08:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Light to occasionally moderate snow accumulated to 2 to 6 inches across portions of southeast South Dakota near and south of Interstate 90. Warm surface temperatures led to mostly a brief slushy accumulation on roadways, but bridges became treacherous with up to a dozen minor accidents along Interstate 29 south of Sioux Falls. Snowfall of 4.8 inches was measured near Tea, with 2.5 inches at Canton.

Winter Weather in GREGORY, SOUTH DAKOTA
From 14-OCT-18 01:00:00 to 14-OCT-18 06:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

Light to occasionally moderate snow accumulated to 2 to 6 inches across portions of southeast South Dakota near and south of Interstate 90. Higher totals measured were 7 miles east of Fairfax (6.0 inches), 4 miles southwest of Burke (4.0 inches), 8 miles southwest of Herrick (4.0 inches), and near Bonesteel (3.0 inches).

Winter Weather in DOUGLAS, SOUTH DAKOTA
From 14-OCT-18 02:00:00 to 14-OCT-18 06:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

Light to occasionally moderate snow accumulated to 2 to 6 inches across portions of southeast South Dakota near and south of Interstate 90. Snowfall of 5.0 inches was measured 6 miles west of Parkston, with 3.1 inches at Armour and 2.0 inches 10 miles west of Dimock.

Winter Weather in YANKTON, SOUTH DAKOTA
From 14-OCT-18 01:00:00 to 14-OCT-18 07:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Light to occasionally moderate snow accumulated to 2 to 6 inches across portions of southeast South Dakota near and south of Interstate 90. Visibility dropped to 1 mile or below for nearly two hours, but warm surface temperatures resulted only in a brief slushy accumulation on roads. Snowfall of 2.0 inches was measured at Yankton.

Winter Weather in MOODY, SOUTH DAKOTA
From 14-OCT-18 02:00:00 to 14-OCT-18 07:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

Light to occasionally moderate snow accumulated to 2 to 6 inches across portions of southeast South Dakota near and south of Interstate 90. Snowfall of 5.1 inches was measured 6 miles northwest of Dell Rapids, with 1.5 inches at Flandreau.

Winter Weather in MINNEHAHA, SOUTH DAKOTA
From 14-OCT-18 01:00:00 to 14-OCT-18 08:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Light to occasionally moderate snow accumulated to 2 to 6 inches across portions of southeast South Dakota near and south of Interstate 90. Snowfall from 3.0 to 5.0 inches was measured around the Sioux Falls metro area, including 4.5 inches at Colton and 4.1 inches at Hartford. Visibility dropped to a mile or less for up to two hours. Warm surface temperatures resulted in brief slushy accumulations for most roadways, but bridges became treacherous with numerous minor accidents in the early morning hours. Following the snowfall, record cold maximum temperatures occurred in Sioux Falls on the 14th and 15th.

Winter Weather in HUTCHINSON, SOUTH DAKOTA
From 14-OCT-18 02:00:00 to 14-OCT-18 06:30:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Light to occasionally moderate snow accumulated to 2 to 6 inches across portions of southeast South Dakota near and south of Interstate 90. Snowfall of 5.0 inches was measured at Parkston, with 4.5 inches at Tripp, 3.5 inches 11 miles south of Emery, and 3.0 inches at Menno.