# Snow Calculator

You can use this snow weight calculator to determine the weight of snow that has recently fallen. In this article, we will describe how the snow weight calculator works and how you can use data pertaining to historical snowfall and snow depth to forecast the chance of it being a white Christmas in different areas.

You can compute snow weight in four simple steps:

1. Input the air temperature
2. Input the average depth of snow
3. Input the surface area that is covered by the snow
4. Click on the "Calculate" button to generate the results.

## How the Weight of Snow is Calculated

Snow is formed of ice crystals. Its weight is determined by the density and volume of these crystals. Snow that is fluffy and loosely packed weighs a lot less than snow that is wet or densely packed.

The total weight of snow can be computed by multiplying the volume of snow by its density using the following formula:

Ms = Vs * ρs

Where: Ms = mass of snow [kg], Vs = volume of snow [m3], Vs = Area (A) * Depth (D), ρs = density of snow [kg m-3]

The density of snow directly impacts its weight and is determined by the structure of the ice crystals from which it is formed and the volume of those crystals. Generally, the density of snow is impacted by three different factors:

1. The processes that take place in the cloud directly influence the size and shape of the ice crystals as they develop.
2. The processes that modify the ice crystals as they fall to the ground.
3. The compaction that occurs at the ground level as a result of the metamorphism in the snow and the weather conditions.

Our snow weight calculator determines the density of snow according to the air temperature. Where the air temperature is below freezing, the approach proposed by Hedstrom and Pomeroy (1998) is employed, and where the air temperature is above freezing, the approach proposed by Pomeroy and Gray (1995) is used. These formulas are as follows:

ρs = 67.92 + 51.25 * e (T / 2.59) , (T ≤ 0)

ρs = min [ 200, (119.17 + 20 * T) ] , (T > 0)

Where: ρs = density of snow [kg m-3], T = air temperature in Celsius [°C], e = 2.718282

Snow Weight Calculator

Results

You may also be interested in our Rain-to-Snow Conversion Calculator

## Can We Forecast a White Christmas?

The exact criteria that are applied to determine whether it is a white Christmas vary from region to region. In the majority of countries, it basically entails that if there is snow on the ground on either Christmas Eve or Christmas Day (depending on the local tradition in the respective area of the world), it is deemed to be a white Christmas. However, some countries have a much stricter assessment approach.

In the UK, many people perceive it to be a white Christmas if there is complete snow cover on Christmas day. However, officially, it is only deemed to be a white Christmas is snow is falling from the sky at any time on the 25th of December. Snow is most likely to fall on Christmas day in Scotland.

The table presented below contains historical data extracted from the UK Met Office and contains the data compiled by weather stations throughout the UK over the past 25 years. This data can be used to compute the probability that there will be a white Christmas in the current year.

Region % Chance
Scotland 55%
East of England 26%
North East 21%
West Midlands 19%
South East 15%
Northern Ireland 14%
South Wales 12%
North West 12%
South West 10%
Yorkshire & the Humber 9%
North Wales 9%
East Midlands 9%

In the US, it is not officially considered to be a white Christmas unless the snow reaches a depth of at least 2.5 cm or 1 inch by 7:00 am local time on Christmas Day.

The table presented below contains historical data extracted from World Weather Online. This data represents the probability that there will be a white Christmas in the respective state of the US based on the average snowfall observed in that area in December.

State % Chance
Vermont 52%
Minnesota 37%
Montana 34%
Michigan 33%
North Dakota 32%
Wisconsin 32%
Utah 30%
Idaho 28%
Maine 25%
South Dakota 25%
Wyoming 23%
Iowa 22%
Indiana 21%
New Mexico 21%
West Virginia 20%
New York 20%
Ohio 19%
New Hampshire 19%