The Chelsea 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.
Sunny
Partly cloudy; warmer
Mostly sunny
Sunny
Mostly sunny
Partly cloudy
Mostly sunny
18° on Nov. 13, 2019, the coldest reading for this week of the year since 1895. Next is 19° in 1940.
Chelsea’s center stands about 520 ft above sea level. Within three miles the land runs from 480 ft to 1,010 ft, a difference of 530 ft: hilly country. The highest named summit within 15 miles is Signal Mountain, about 1,560 ft, 5 miles northeast.
Under the town center the state geologic map shows Pottsville Formation (upper part) (shale, siltstone, sandstone), from the Carboniferous, 299 to 324 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 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.
Shale. Age: Carboniferous, 299 to 324 million years old. About 8 mi of the line.
Shale, siltstone, sandstone. Age: Carboniferous, 299 to 324 million years old. About 7 mi of the line.
Sandstone, shale, siltstone. Age: Carboniferous, 299 to 324 million years old. About 6 mi of the line.
Shale. Age: Carboniferous, 324 to 359 million years old. About 2 mi of the line.
Shale. Age: Carboniferous, 324 to 359 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 Chelsea reaches Mobile Bay and the Gulf of America by way of North Fork Yellowleaf Creek, Yellowleaf Creek, the Coosa, the Alabama and the Mobile: about 460 river miles.
Lake on the way: Lay Lake.
310 miles of the trip are on the Alabama.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Chelsea; river miles along the main stem, rounded.
Chelsea has a humid subtropical climate. Summer afternoons average 91° in July; winter nights fall to about 35° in January. About 57 inches of rain fall in a normal year, with about 1 inch of snow.
On November 14 Chelsea normally reaches 65° and falls to 43°. The record high is 82°, in 1955; the record low 23°, in 2014. The most rain on this date, 4.43 in, fell in 1929.
Normals 1991–2020 and records since 1895 from the Birmingham Area threaded record (Birmingham Airport, 17 miles north-northwest). NOAA, through RCC-ACIS.
