Nelson's log

Snowfall hillshades

Garrett Dash Nelson has a lovely visualization of snowfall for 2017-2018; take a look! His code is very simple. A Python script to download data from NOAA, then some bits of shell scripts using GDAL to reproject, hill shade, and convert to an animated GIF.

I wanted to see what this treatment would look like over years so I did my own little thing based on his. Here’s the image processing script I used

set -eux
for y in 2014 2015 2016 2017 2018; do
  gdalwarp -t_srs "EPSG:5069" -srcnodata "-99999" sfav2*to_$y*.tif $d-warped.tif
  gdaldem hillshade -z 1500 $d-warped.tif $d-hillshade.tif
  gdal_translate -of JPEG $d-hillshade.tif $d-hillshade.jpg

And the images below. Starting at 2013-2014, and the final image is just a partial year of 2017-today. It’s not a great result TBH; the years end up looking pretty much the same and not that different from an altitude graph. In California you can’t see the low snowfall years of 2014-2015 and 2015-2016 vs the high snowfall 2016-2017, for instance.