2018 was the wettest year on record across the Washington region. All three of the official climate stations — D.C., Baltimore and Dulles — reached a new high water mark, in addition to many other spots.
A location in the suburbs of Baltimore took it a step farther. Catonsville, Md., posted 84.56 inches of precipitation in the calendar year.
Last week, the National Oceanographic and Atmospheric Administration’s State Climate Extremes Committee met and voted in favor of declaring Catonsville’s seven feet of rain a new Maryland state record for annual precipitation.
The measurement was made by volunteer weather observer Tom Atkins, a participant in the CoCoRaHS network. CoCoRaHS stands for Community Collaborative Rain, Hail & Snow Network and is composed of thousands of citizen scientists who gather precipitation data, many in their backyards.
Considering that there are only a few hundred official NOAA sites for measuring precipitation, the supplemental observations provided by CoCoRaHS volunteers are critical for filling gaps in an otherwise patchwork network.
The Baltimore Sun profiled Atkins and his CoCoRaHS setup in February. It reported that the National Weather Service had visited Atkins home to inspect his rain gauge and its surroundings but didn’t “see anything amiss.”
Atkins, according to the Sun, received 9.47 inches of rain in a single day from the same extreme event which engulfed nearby Ellicott City in a second “1,000-year flood” in three years. That exceptional rainfall helped Catonsville make Maryland climate history.
Catonsville’s 84.56 inches bests the previous Maryland annual precipitation record of 78.32 inches. The old high mark was recorded in 1903 in a northern Maryland location known as Bachman’s Valley, to the north of Westminster just miles from the Pennsylvania border.
Several other locations in Maryland also surpassed that old 1903 total, including sites near Thurmont and Mechanicsville. Both locations had precipitation amounts topping 80 inches in 2018.
Maryland was not the only state to set a new annual maximum precipitation record in 2018. It was quite wet more broadly — both in the Mid-Atlantic and parts of the Upper Midwest:
- In South Carolina, the 123.45 inches in Jocassee may soon be declared a state record.
- The nearly 140 inches of rain at Mount Mitchell, N.C., is likely to set a new mark
- The 97-plus inches in Montebello, Va., (Nelson County) is in the running for a state record.
- Minnesota broke its state precipitation record in more than one location.
The new record in Maryland, as in other places, was boosted by a number of massive rainfalls. For example, in neighboring Washington, there were a record number of days (24) with at least one inch of rainfall. The abundance of extremely rainy days and the widespread repeated nature of such soaking rainfall was generally consistent with expectations in a warming world.