That is the real average error, based on 754 station comparisons. Nobody prints that number. We did. Photo: Famartin, CC BY-SA.
Weather balloons, radar and satellites feed every model a snow forecast depends on. Photo: NOAA.
Stations like this one are how a forecast gets checked against what actually fell. Photo: USDA NRCS Montana.
The National Weather Service's own point forecast beats most apps inside a week. Photo: Chris Light, CC BY-SA.
Storms over 10 inches got under-forecast the most. See the full lead-time data and why.