The first SnowWatch alert of the season went out this morning as clear skies and calm winds nudged temperatures below freezing in some city spots. The above image accompanied the alert and shows road surface temperatures (boxed) and air temperatures (unboxed). The key phenomena worth watching are the 2-5° differences between air and road temperatures, and their trends.

SnowWatch is a temperature and snowfall warning system operated the Seattle Department of Transportation (SDOT). It was modeled after SPU’s RainWatch and was also developed by the University of Washington’s Department of Atmospheric Sciences. Like RainWatch, SnowWatch enables more efficient management of resources, which for SDOT usually means prioritizing anti-icing or snow removal activities.

References:
Seattle SnowWatch
SPU Climate Change program
Email SPU’s Climate Change team