16 Jan 2012

Cold temperatures and no wind will certainly help surface hoar to develop.

At 06:00 hrs it was -18 at 2280 meters with south winds 40-50 KPH. Wind chill puts the temperature at -40. At 1550 meters the temperature is -13, relative humidity at 90 %, and the barometer is on a very slight decline. In the valley it is -9. If you go into the alpine today be sure to dress extra warm and keep all exposed skin covered.

For the latest Avalanche Advisory click here: Avalanche Advisory

For a brief explanation of wind chill and a wind chill converter click here: Wind Chill

Another explanation is from Wikipedia:
The human body loses heat through convection, evaporation, conduction, and radiation.[1] The rate of heat loss by a surface through convection depends on the wind speed above that surface: the faster the wind speed, the more readily the surface cools. For inanimate objects, the effect of wind chill is to reduce any warmer objects to the ambient temperature more quickly. It cannot, however, reduce the temperature of these objects below the ambient temperature, no matter how great the wind velocity. For most biological organisms, the physiological response is to maintain surface temperature in an acceptable range so as to avoid adverse effects. Thus, the attempt to maintain a given surface temperature in an environment of faster heat loss results in both the perception of lower temperatures and an actual greater heat loss increasing the risk of adverse effects such as frostbite and death.