The Alpena 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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3.15 inches of rain fell in two days, the most for this week of the year since records began in 1892. The next wettest, 3.10 inches, fell in 1978.
Alpena’s center stands about 1,140 ft above sea level. Within three miles the land runs from 1,080 ft to 1,560 ft, a difference of 480 ft: hilly country. The highest named summit within 15 miles is Pickert Point, about 2,320 ft, 15 miles south.
Under the town center the state geologic map shows Boone Formation (limestone), from the Carboniferous, 324 to 359 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 15×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Limestone. Age: Carboniferous, 324 to 359 million years old. About 12 mi of the line.
Sandstone, shale, limestone. Age: Carboniferous, 324 to 359 million years old. About 5 mi of the line.
Sandstone. Age: Carboniferous, 299 to 324 million years old. About 3 mi of the line.
Dolostone. Age: Early Ordovician, 471 to 487 million years old. About 2 mi of the line.
Shale, sandstone. Age: Carboniferous, 299 to 324 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.
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 Alpena reaches the Gulf of America by way of Long Creek, the White River and the Mississippi: about 1,180 river miles.
Lake on the way: Table Rock Lake.
620 miles of the trip are on the Mississippi.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Alpena; river miles along the main stem, rounded.
Alpena has a humid subtropical climate. Summer afternoons average 89° in July; winter nights fall to about 27° in January. About 44 inches of rain fall in a normal year.
On November 14 Alpena normally reaches 60° and falls to 38°. The record high is 80°, in 1955; the record low 5°, in 1908. The most rain on this date, 1.53 in, fell in 1993.
Normals 1991–2020 and records since 1892 from the Harrison Area threaded record (Harrison Boone County Airport, 8 miles east-southeast, 230 ft higher). NOAA, through RCC-ACIS.
