The Pasco 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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77° on Nov. 13, 1999, the hottest reading for this week of the year since 1894. Next is 73° in 1896.
Pasco’s center stands about 390 ft above sea level. Within three miles the land runs from 330 ft to 480 ft, a difference of 150 ft: gently rolling country. The highest named summit within 15 miles is Jump Off Joe, about 2,190 ft, 9 miles south.
Under the town center the state geologic map shows Alluvium (silt, sand), from the Holocene, less than 12,000 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 12×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Fine-detrital, coarse-detrital. Age: Pleistocene, less than 2.6 million years old. About 12 mi of the line.
Basalt. Age: Early Eocene to Pliocene, 2.6 to 56 million years old. About 5 mi of the line.
Silt, sand. Age: Pleistocene, less than 2.6 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.
Silt. Age: Pleistocene, less than 2.6 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 Pasco reaches the Pacific Ocean by way of the Columbia: about 320 river miles.
Lake on the way: Lake Umatilla.
210 miles of the trip are on the Columbia.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Pasco; river miles along the main stem, rounded.
Pasco has a cold semi-arid climate. Summer afternoons average 92° in July; winter nights fall to about 27° in December. About 8 inches of rain fall in a normal year.
On November 14 Pasco normally reaches 50° and falls to 32°. The record high is 71°, in 2021; the record low 6°, in 1955. The most rain on this date, 0.53 in, fell in 1966.
Normals 1991–2020 and records since 1894 from the Tri-Cities Area threaded record (Pasco Tri Cities Airport, 2 miles north-northwest). NOAA, through RCC-ACIS.
