As large plows and brooms raced down runways, pushing and blasting snow off the Toledo Express Airport on Sunday, Steve Arnold walked slowly toward a white pipe near a chain-link fence at the runway field and stuck a metal ruler into the ground.
When it snows, that process is repeated every six hours. Planes swoop in for landings or take off or taxi on runways, and an airport employee, normally a police officer, takes the snowfall reading that you hear about in the news.
Late Saturday night, airport staff found 0.3 inches of snow on the ground, giving the city a total of 25.3 inches for February, just barely breaking the 25.2-inch record set in 2011.
Probably. Maybe.
There’s a nonspecified, yet widely accepted, margin of error in snow-accumulation data, so quibbling over a tenth of an inch is an exercise in futility. You can call this February the record, just don’t swear on a Bible when you do it.
Measuring snowfall totals is not a straightforward process, said John Mayers, a meteorologist at the National Weather Service office in Cleveland. Many factors can alter measurements, and northwest Ohio is a particularly tricky region in which to get measurements, he said.
Temperature, for instance, will affect how snow accumulates. Very cold temperatures tend to make snow light and fluffy, causing it to pile up faster, Mr. Mayers said. A reading taken while that snow is still falling could be higher than an hour later, when the snow has had time to settle.
Air moisture also can be a factor. And then there’s the wind. The National Weather Service uses two methods to measure snowfall.
An automated system collects snow and then heats it. The precipitation amount is then measured, and snowfall totals are calculated based on the air-temperature readings. The second method, used in conjunction with the automated system, involves observers who have boards set on the ground in specific locations. They check the snowfall totals by hand every six hours.
Wind can drift snow onto or off the boards, skewing readings. There are times, Mr. Mayers said, where it will snow and a board will be totally bare, causing observers to scratch their heads. Toledo is especially difficult because it’s flatter than much of the state, a conducive environment for snow drifts.
So, why bother measuring the stuff?
“Because people want to know how much snow fell,” he said.
It’s not that the numbers are totally off, and staff at the airport tries to get the numbers as accurate as possible.
The rule of thumb, said Mr. Arnold, director of airport operations, is to simply use your head. If there’s only a dusting on most of the ground and the snow board is covered by a couple of inches, chances are most of the snow was blown onto the board. Instead of rigidly sticking to the board position, sometimes you just have to literally take a step back.
A network of volunteers throughout the area also does readings. The weather service checks these figures to see if the official readings are way off.
Weather observers who work at airports are trained to report snowfall totals, but they aren’t National Weather Service staff. In most cases, they are Federal Aviation Administration workers. Toledo doesn’t have a dedicated observer as most airports do, Mr. Mayers said, which is why the security staff generally takes the readings.
No matter the pinpoint accuracy, the weekend snow prompted Erie, Fulton, Huron, Lucas, Putnam, Sandusky, and Seneca counties to declare Level 1 snow emergencies on Sunday.
By Sunday night, the National Weather Service — and the people at the airport — had reported a total of 4.1 inches for the day.
Contact Nolan Rosenkrans at: nrosenkrans@theblade.com or 419-724-6086, or on Twitter @NolanRosenkrans.
First Published March 2, 2015, 5:00 a.m.
