Why, why, why: What's it all about?
Whenever a "significant" storm brings a good amount of fresh snow to the Alps, Ullr and its oracle are known to give an estimate of the expected amount of fresh snow as a PowderAlert. In a PA, not only the amount but also a rough core zone is mentioned. The prediction game is held at a measuring station in the core zone, namely to see how much fresh snow has actually fallen or was predicted by you. For each PA, the measuring station, the period over which the prediction is made, the deadline for submitting a prediction and the initial snow depth are stated.
Snowfall total
The figure in question is the snowfall total in centimetres. In the PG Prediction Game, the new snow total is defined as the maximum snow depth minus the initial snow depth - the image illustrates this graphically. In the example shown, the prediction period is 48 hours with an initial snow depth of 75 cm. During these two days it most probably snowed most of the time. In the last few hours it snowed less or not at all, so that the snow cover settled and compacted. The maximum snow depth was 128cm. This results in the following new snow total: 128-75=53cm.
