Boulder's First Snow

Tools
python, pandas, matplotlib


I grew up in the southeast where a single snowstorm a season was something to talk about. In Boulder, Colorado, we average about 71 inches (180 cm) of snowfall per year. Instead of talking about whether or not it’s going to snow each season, we instead talk about when the first snow is going to arrive. Since moving to Boulder, I have made an updated plot every year with the date of the first snow.



One might anticipate that there is a climate change signal associated with the date of first snow. Note, however, that precipiation is a noisy process and it’s unlikely for the human impact on precipitation to be evident on such a small spatial scale within even this century (see some work by Clara Deser at NCAR). Further, the human impact would probably be more evident in the frequency of intense snowstorms or on the season total. Thus, we don’t see any statistically significant change in the date of the first snow.



I also thought it would be interesting to see whether or not the first snow day indicates how much snow we’ll get over the whole season. That seems unlikely to be true.