The Winthrop 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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−10° on Nov. 16, 1959, the coldest reading for this week of the year since 1906. Next is −8° in 1955.
Winthrop’s center stands about 1,770 ft above sea level. Within three miles the land runs from 1,720 ft to 3,240 ft, a difference of 1,520 ft: steep hill country. The highest named summit within 15 miles is North Gardner Mountain, about 8,880 ft, 15 miles west.
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 4×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Granite. Age: Precambrian to Eocene. About 9 mi of the line.
Arkose. Age: Early Cretaceous to Late Cretaceous, 66 to 113 million years old. About 5 mi of the line.
Graywacke, argillite, siltstone. Age: Jurassic to Late Cretaceous, 66 to 202 million years old. About 4 mi of the line.
Andesite. Age: Late Cretaceous, 87 to 100 million years old. About 4 mi of the line.
Silt, sand. Age: Holocene, less than 12,000 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.
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 Winthrop reaches the Pacific Ocean by way of the Methow and the Columbia: about 570 river miles.
Lake on the way: Lake Umatilla.
240 miles of the trip are on the Columbia.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Winthrop; river miles along the main stem, rounded.
Winthrop has a dry-summer warm-summer continental climate. Summer afternoons average 86° in July; winter nights fall to about 15° in January. A normal year brings about 59 inches of snow; with the rain, that comes to about 15 inches of water.
On November 14 Winthrop normally reaches 42° and falls to 25°. The record high is 60°, in 1917; the record low −1°, in 1955. The most rain on this date, 0.60 in, fell in 2021.
Normals 1991–2020 and records since 1906 at Winthrop 1 WSW, here. NOAA, through RCC-ACIS.
