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When flakes fell on Washington Friday morning, debate broke out within earshot of The List about the precise nature of the precipitation. With some describing it as “snow” and others insisting that “flurry” was correct, The List got interested. She consulted WJLA meteorology team members Doug Hill, Bob Ryan, and Chris Naille for their thoughts on when a flurry becomes snowfall.

1. Flurry, dusting, snowfall, heavy snow subject to individual interpretation

   Though the National Weather Service provides official definitions for some of these designations, Doug Hill says there is an element of subjectivity when describing frozen precipitation. “They’re subjective terms that are used by people the same way,” he says. This was not, he says, covered in his study of meteorology.

2. Accumulation is less important than volume and intensity

   “It could snow for three days and be 30 degrees,” says Hill. “Nothing would accumulate,” but that doesn’t mean it’s still not snowfall. “It has to do with volume and intensity,” he explains.

3. Flurries: Nothing but a number

   Chris Naille gauges flurries quantitatively. “It’s just a matter of numbers,” he says, referring the number of flakes in the air.

4. Flurries can change designation based on their human impact

   “If people are talking about it but nothing is really affected, it’s flurries,” says Bob Ryan. “If it begins to interfere with people, it’s snow.” Thus, Friday’s flurry can be fairly called a “mini-storm,” says Ryan, “because it did cause traffic accidents and affect travel.”

5. Steadiness affects flurry designation

   Ryan ceases to call very light snow a flurry if it’s steady for 2-3 hours, regardless of accumulation.

6. Local weather patterns a factor

   Ryan says that precipitation qualifies as “heavy snow” when 4 inches of accumulation are achieved. “In Buffalo, that might be a flurry,” he says. “In different locations there might be a different threshold for heavy snow.”

7. Flurry discussion turns meteorologist philosophical about all forms of precipitation

   “Rain is categorical,” says Hill. “Rain is rain. Rain is the opposite of snow. Flurries are the frozen equivalent of sprinkles.” He adds, “The atmosphere is always in motion, and it defies understanding sometimes.”