The maps show the whole country at one moment. This shows one place through the whole storm: what the blend said would fall in each six hours, how wide its own range was, how the forecast moved from one run to the next, and what the snowfall analysis measured. Use ↑ and ↓ to walk the storm track.
A grid cell is not a gauge. Both the forecast and the analysis are 2.5 km averages sampled at the city's coordinates, so a valley town and the ridge above it can share a number that suits neither exactly. These are not station observations and should not be read as one.
The range stops at f054. Past two and a quarter days the blend publishes one snowfall number and nothing about its spread. Where a run shows no band, that is the product ending, not the uncertainty ending.
A negative lead is a nowcast. Runs initialised after the window opened are still shown, because watching a forecast settle once the storm is underway is part of the story — but they are not a forecast of the whole event and their totals cover only what was still to come.