Here Nor There: White Christmas (Keys and Legends #2)

Merry Christmas Bloggers!!! Odds are that like myself you are experiencing a Christmas that is less frozen and snow covered than you would like. Here in south central Pennsylvania during the last two weeks we have received a foot of snow only to have it melt during three freakish 60 degree days that were followed by a rain storm. So despite it being a brisk 26 degrees outside there is not a snowflake to be had. In the last ten years I can only remember three Christmases in which snow was on the ground and only one in which it was actually snowing. This got me to thinking...If it is so hard to come by the fabled white Christmas in south central PA where would a person have to be in the U.S. to avoid disappointment?

Below are two maps; one from USA Today with data from the National Climate Data Center and the other from Climate Central made using data acquired from the National Oceanic and Atmospheric Administration. As one would expect these maps show that areas with higher elevation, higher latitude, and those areas prone to lake effect are the most likely to experience a Christmas that is white. If you are a resident of the Rocky Mountains / Catskills or Northern Maine, Michigan, Minnesota, Wisconsin, Idaho, Washington, New York, Vermont, New Hampshire, Montana, or Washington you are 90% certain to experience a white Christmas. Contrastingly, if you are a resident of the deep south or Florida you are more than likely outta luck. (Sorry Key West!).

As a side note you can see that these two maps are displaying more or less the same information. They both show high and low probability of snow in the same areas but the map from USA Today is considerately easier to interpret. The reason for this is that the USA Today map uses a qualitative color scheme. This means that the colors for each percentage are very different from their neighbors. (Example: the 26-40% range is a dark blue while the 41-50% range is gray.) This qualitative approach makes it easier for the eye to pickup on subtle changes especially in congested areas with a lot of change like Colorado or Nevada. The Climate Central map uses a sequential color scheme which means that you start with one color hue and change its saturation level as the percentages it represents change. In this case the darkest blue is no snow and the lightest blue - white is a very high percentage of snow. The sequential color scheme is a perfectly fine scheme in its own right but is not best suited for a map with complex changes such as this one.

So have a Merry White Christmas to those of you in the north and better luck next year to the rest of you, may the odds be ever in your favor.

Map of Snow Fall Percentages from USA Today (Over the Last 30 Years)