Tis the season to be snowy

USGS recently published a map of snow cover index for the coterminous US. They could have just gone with a standard depiction showing a raster coverage with some sort of colour gradient to show low to high. Job done. Except they didn’t.

A map of the contiguous U.S. using a snowflake hex pattern to show snow persistence over a 20-year period. Snow persistence is measured as the snow cover index, or the average fraction of time snow was on the ground from Jan 1 to. July 3 from 2001-2020. Snowier places are white with snow, emphasizing the Rocky Mountains and Sierra range in the western U.S., and Maine in the northeast. The majority of the southern half of the country is within a 0-10% snow cover index. Data from: https://doi.org/10.5066/P9U7U5FP

They binned the data into hexagons (the de rigueur choice for binning) and then used a snowflake symbol set within each hexagon, and graded them from near white (most snow cover) to almost the background colour of the map (least snowfall cover. It’s an effective, playful design choice that works.

A zoomed in view of the snowflake hex pattern in the west. Each snowflake is identical and fits within a hexagon, mosaicked together to create the map.

I also appreciate the choice of Albers for the projection which means the hexagons are, by design, equal area. Far too many hex-binned maps use Web Mercator which simply means the analysis is incorrect as the overlaying hexagons occupy more or less land area depending on their latitude.

I really like this simple but joyous map. And it gave me an idea…stay tuned!

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