The St. Gabriel 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.
6.60 inches of rain fell in two days, the most for this week of the year since records began in 1937. The next wettest, 4.80 inches, fell in 1961.
St. Gabriel’s center stands about 20 ft above sea level. Within three miles the land runs from 0 ft to 70 ft, a difference of 70 ft: gently rolling country.
Under the town center the state geologic map shows Natural Levees (silt, clay), from the Holocene, less than 12,000 years old.
The section below crosses 3 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 64×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Silt, clay. Age: Holocene, less than 12,000 years old. About 14 mi of the line.
Clay. Age: Holocene, less than 12,000 years old. About 5 mi of the line.
Clay, silt, sand. Age: Pleistocene, less than 2.6 million years old. About 5 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 St. Gabriel reaches Lake Pontchartrain and the Gulf of America by way of the Bayou Manchac and the Amite: about 80 river miles.
Lake on the way: Lake Maurepas.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of St. Gabriel; river miles along the main stem, rounded.
St. Gabriel has a humid subtropical climate. Summer afternoons average 90° in July; winter nights fall to about 43° in January. About 62 inches of rain fall in a normal year.
On November 14 St. Gabriel normally reaches 71° and falls to 50°. The record high is 84°, in 1993; the record low 32°, in 1975. The most rain on this date, 2.25 in, fell in 1989.
Normals 1991–2020 and records since 1937 at Carville 2 SW, 4 miles south-southwest. NOAA, through RCC-ACIS.