About the telemetry data
The source data for the PowderStash telemetry graphs comes from a network of remote weather stations that are installed and maintained by the Northwest Weather and Avalanche Center. The raw data from these stations is uploaded hourly onto the Internet by the NWAC and PowderStash "scrapes" this data from the raw data logs and graphs it in an easy-to-understand format. The stations in this network are subject to outages (usually caused by severe weather conditions) and missing or inaccurate data may result. Please view spikes and gaps with suspicion.
About the snowfall and base depth views
Only about half of the remote weather stations support a 24-hour snowfall measurement, and those that do re-set the value to zero every twenty-four hours, usually at 6am. Therefore the 24-hour view does not represent snowfall in the last 24-hours, but snowfall since 6am. This results in a graph with a 'sawtooth' appearance. For those stations that do not have a 24-hour measurement PowderStash displays a graph of the 24-hour change in the base depth. This essentially shows the 24-hour 'settled' snowfall, which is a very conservative picture of the actual snowfall. A six-inch increase in the base depth means easily a foot of new snow fell.
About the scoring of conditions
PowderStash considers the perfect day in the mountains to be clear skies with two feet of fresh that fell the night before under cold temperatures and no wind. The PowderStash scoring algorithm works by identifying precipitation "events" (periods of snow/rain) and giving them a score based on the amount of precipation, the temperature at which it fell, how long it fell, and how much wind accompanied the event. The score is then maintained over time as long as nothing happens which deteriorates the snow (wind or rain). If any of the three data points (temperature, precipitation, and wind) is missing no score is assigned for that hour.
About the PowderStash software
The PowderStash data-scraping and graphing software was created in 1999 as a programming project for learning the Java programming language. It went online for public use in December 2001. Originally it was implemented as a Java applet running in the user's browser, the applet downloaded a small data file which it would then graph. This architecture was designed with the dial-up user in mind, which at that time was the majority of people on the web. Doesn't that seems like eons ago? Upon release there were many platform and browser issues with Java applets so the applet was converted to just generate gifs, which is how the software still runs.
