Snow Accumulation Patterns (warm, temp, day, storm)

[Calvert Hall '62]

Sometimes, the snow starts accumulating on the grass, while the asphalt driveway remains merely wet. Presumably, the blacktop is warmer. Duh. As the snow continues, it starts accumulating on the driveway too.

Other times, the accumulation starts on both the grass and driveway simultaneously.

But one day last week, it started accumulating on the driveway but not the grass, at least not at first. The driveway was colder??????

[Ariete]

If the conditions are cloudy for long and temps moderate, the pavement is not warmer than the surrounding environment, as it doesn't conserve heat as there's nothing to conserve. The wet humid grass may be warmer than an unused pavement. The roads are weared down by the warm tires of cars, so a unused parking lot is colder than a street with traffic.

Here up north, unused paved areas always accumulate more snow than the extremely humid (and warmer) grass. Trafficked streets don't, as warm tires with high friction roll over all the time and create warmth.

[Cambium]

Originally Posted by Calvert Hall '62

But one day last week, it started accumulating on the driveway but not the grass, at least not at first. The driveway was colder??????

Wild guess here without knowing the details. Soil/Grass had moisture while driveway was dry and cold. So the flakes would melt easier on the grass at the time than the driveway because the flakes were landing on a semi wet surface(grass)

Another reason is the soil temp was a degree or so warmer than the driveway itself.

If you're measuring, remember to use a flat board(white) in an open area and not the grass or a sloped area. And after a measurement, wipe the board clean, write down the measurement, then measure for new accumulations again, even for same storm, same day. This is because snow compacts. Add all your measurements and that's your storm total.