Monday, August 3, 2015

Snow forecast: 400 to 800 pounds

When it comes to shoveling, weight means more than depth.

Snow forecast: 400 to 800 pounds


When snow is in the forecast, most people simply want to know how many inches.

Those of us left with the task of moving it would be better served by knowing how many pounds.

Inch counts are elusive quantities. How much snow pops out of a given amount of moisture depends on physical processes that not even the world’s most-sophisticated computer models can capture precisely.

As a general rule, the colder it is, the bigger the ratio of snow to water-equivalent of the precipitation.

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On average around here, about a foot of snow falls for every inch of precipitation, but that’s merely a guideline.

For the record 30.7 inches of snow measured on Jan. 7-8, 1996, at Philadelphia International Airport, the total melted liquid came to 1.55 inches.

The latest best guess of the precipitation total is around 0.5 inches. Taking that 12:1 average ratio at face value, that translates to 6 inches, but that liquid amount could end up as 4 inches or fluff up to 8.

We can say with certainty that whether it’s 4 or 8, if the precipitation comes in at 0.5, the weight would be the same.

A half inch of water over a square foot of space weights about 2.6 pounds. Thus, a typical 5-foot-wide sidewalk that is 30 feet long would cover 150 square feet, thus the snow would weigh close to 400 pounds.

Double that for a 300-square-foot driveway.

One variable you might have to consider when weighing the weight of the shoveling task confronting you is that near-blizzard winds are going to be howling for awhile.

That could greatly reduce or increase what you have to move.

In short, you might able to persuade your neighbor that he needs to come and remove his snow from your driveway.

Inquirer Weather Columnist
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About this blog

Everyone talks about the weather, and here we write about it.

When we’re around and conditions warrant, we’ll keep you updated about what’s coming, but we will do our best always to discuss weather and climate developments in context and remind you that nothing in the atmosphere happens in a vacuum.

Tony Wood has been writing about the atmosphere for The Inquirer for 26 years.

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Tony Wood Inquirer Weather Columnist
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