Reporting Jason DeRusha
MINNEAPOLIS (WCCO) — The snow totals are impressive: Up to 15 inches of snow in some parts of Minnesota. But the wind is equally impressive, blowing the snow all over the place. So how does the weather service measure the snow?
“Today’s a tough day because the snow has been blowing around,” said Michelle Margraf, a meteorologist with the National Weather Service Chanhassen office.
On a normal day, the snow measuring method is decidedly low-tech: A stainless steel ruler and a white flat board.
“We use a ‘snowboard.’ If you measure in the grass, you’ll be getting the depths of the grass plus the snow that fell,” said Margraf.
She takes measurements all over the board and then averages them to come up with a snowfall amount. Every six hours she measures and clears off the board.
“The reason we color it white is so the snow won’t melt, it’ll be cooler,” she added.
But when the wind is blowing, that measurement can be highly unreliable.
“Today, because we have the danger of blowing and drifting contaminating the measurement, we actually take the rain gauge that’s behind us,” said Margraf and they use the snow that fell in the gauge.
She brings the snow inside the weather service office, runs hot water on the canister and melts it into water.
“Between 6 a.m. and noon, there was 0.02 inches of water,” said Margraf.
For this storm, it’s a dry snow, so 1 inch of water equals 20 inches of snow. Using that ratio, Michelle’s 0.02 inches of water translates to 0.4 inches of snow.
That’s the number that will be added to the total.
“We have lots of automated equipment to measure weather. But snow is something that can’t be automated. We still have human beings measuring the snow because it can be so problematic. It’s an art more than a science,” said Margraf.
