The Welby 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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82° on Nov. 17, 2016, the hottest reading for this week of the year since 1984. Next is 82° in 2025.
Welby’s center stands about 5,160 ft above sea level. Within three miles the land runs from 5,060 ft to 5,450 ft, a difference of 390 ft: rolling country. The highest named summit within 15 miles is Green Mountain, about 6,840 ft, 15 miles southwest.
Under the town center the state geologic map shows Modern alluvium (unconsolidated), from the Quaternary, less than 2.6 million years old.
The section below crosses 5 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 26×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Sandstone, mudstone, conglomerate. Age: Late Cretaceous to Paleocene, 56 to 100 million years old. About 12 mi of the line.
Sand, silt. Age: Quaternary, less than 2.6 million years old. About 7 mi of the line.
Arkose, shale, mudstone. Age: Late Cretaceous to Paleocene, 56 to 100 million years old. About 2 mi of the line.
Unconsolidated. Age: Quaternary, less than 2.6 million years old. About 2 mi of the line.
Gravel, unconsolidated. Age: Pleistocene, less than 0.5 million years old. About 1 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale.
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 Welby reaches the Gulf of America by way of the South Platte, the Platte, the Missouri and the Mississippi: about 2,390 river miles.
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 Welby; river miles along the main stem, rounded.
Welby has a humid subtropical climate. Summer afternoons average 91° in July; winter nights fall to about 19° in January. A normal year brings about 45 inches of snow; with the rain, that comes to about 14 inches of water.
On November 14 Welby normally reaches 56° and falls to 27°. The record high is 79°, in 1990; the record low 1°, in 2014. The most rain on this date, 0.45 in, fell in 1994.
Normals 1991–2020 and records since 1984 at Northglenn, 5 miles north-northwest, 210 ft higher. NOAA, through RCC-ACIS.
