The Flat Willow Colony plate. Relief from Copernicus GLO-30; rivers and lakes from USGS NHD; watersheds from the USGS Watershed Boundary Dataset; roads and city limits from Census TIGER 2024.
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Showers likely; cooler
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79° on Nov. 12, 1999, the hottest reading for this week of the year since 1913. Next is 78° in 1990.
Flat Willow Colony’s center stands about 3,510 ft above sea level. Within three miles the land runs from 3,430 ft to 3,820 ft, a difference of 390 ft: rolling country. The highest named summit within 15 miles is Three Buttes, about 4,100 ft, 15 miles northwest.
Under the town center the state geologic map shows Eagle Formation (sandstone, sandstone-mudstone), from the Late Cretaceous, 72 to 87 million years old.
The section below crosses 10 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 21×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Age: Late Miocene to Holocene, less than 7.2 million years old. About 5 mi of the line.
Sandstone, shale. Age: Late Cretaceous, 72 to 84 million years old. About 4 mi of the line.
Sandstone, sandstone-mudstone. Age: Late Cretaceous, 72 to 87 million years old. About 4 mi of the line.
Shale. Age: Late Cretaceous, 72 to 84 million years old. About 3 mi of the line.
Mudstone, siltstone, sandstone. Age: Early Cretaceous, 100 to 133 million years old. About 2 mi of the line.
Shale. Age: Early Cretaceous, 100 to 113 million years old. About 2 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale. 4 smaller units along the line are not listed.
Heights from Copernicus GLO-90 (a surface model: it includes buildings and tree canopy); summits from USGS GNIS; rivers from USGS NHDPlus HR; rock from the USGS State Geologic Map Compilation.
A raindrop that lands in Flat Willow Colony reaches the Gulf of America by way of Little Wall Creek, North Willow Creek, the Musselshell, the Missouri and the Mississippi: about 3,190 river miles.
Lakes on the way: Lake Oahe, Lake Sakakawea, Lake Fort Peck and Lake Sharpe.
1,170 miles of the trip are on the Mississippi.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Flat Willow Colony; river miles along the main stem, rounded.
Flat Willow Colony has a cold semi-arid climate. Summer afternoons average 86° in July; winter nights fall to about 14° in January. A normal year brings about 43 inches of snow; with the rain, that comes to about 14 inches of water.
On November 14 Flat Willow Colony normally reaches 47° and falls to 24°. The record high is 75°, in 1999; the record low −13°, in 2014. The most rain on this date, 0.16 in, fell in 1930.
Normals 1991–2020 and records since 1913 at Flatwillow 4 ENE, 9 miles northeast, 220 ft lower. NOAA, through RCC-ACIS.
