Investigating Snow, Sleet, & Freezing Rain
As we begin to count the first days of spring and much of the Northeast continues to thaw from the “pi-day nor’easter”, we wanted to visit one of the most difficult parts of the storm for both forecasters and snow removal experts: Sleet. While the amount of sleet which occurred along the East Coast didn’t quite stack up to the 2+ feet of snow which buried parts of Northeast PA and Upstate New York, the changeover to sleet and freezing rain made this storm uniquely difficult for states along the Eastern Seaboard. But why?
There’s an old childhood riddle that fits this scenario quite well: What weighs more, 1-ton of bricks or 1-ton of feathers? While we know they both weigh the same, the concept mirrors our situation. We all know the physical make up of snow: Generally fluffy, powdery, flakes. Sleet on the other hand, is frozen rain drops which form pellets of ice. You can pick sleet up and physically hold them, however you cannot make a snowball out of them because this solid ice will not compact like snow. Freezing rain technically falls as plain rain and when it hits you, feels like plain rain, however often times with air and/or surface temperatures below 32, this “plain rain” will cause a solid glaze of ice on many surfaces. So how do these wintry precipitation types stack up against one another? While the physical feel of each is a bit like comparing apples and oranges, there is a method of comparison.
The common denominator between all precipitation types is water in liquid form. As a general rule of thumb (the key word being general), one inch of liquid precipitation can fall in the form of 1.0 inch of freezing rain (icy glaze), 3.0 inches of sleet, or 10.0+ inches of snow, but it still consists of the same one inch of liquid no matter what form. Judging by the illustration below, if you find yourself digging out from under 3.0 inches of sleet (a fairly rare occurrence), it will feel and weigh the same as digging out from under 10.0 or so inches of snow. Also, if you’re unlucky enough to find yourself in a 1.0 inch freezing rain storm encasing things in ice, it still weighs the same as around 10 inches of snow. This is why tree branches and power lines sag and break under the excessive stress and you’re sitting in the dark with no power.