Roads may become impassable for most vehicles. These are the most dangerous winter storms and can be especially severe when combined with temperatures below 10 degrees. Trees and power lines can be blown down. A high wind warning may be preceded by a high wind watch if the strong winds are not expected to occur for at least 12 hours. Exposure to this combination of strong winds and low temperatures without protective clothing will quickly lead to frostbite or hypothermia or both.
Longer exposure can be fatal.
This is issued for snowfall greater than four, but less than seven, inches in a 24 hour period. The snowfall is usually expected to begin within the next 12 hours. This is issued when the visibility will be significantly reduced or when the roads become snow covered over a large area. Exposure to this combination of strong winds and low temperatures without protective clothing can lead to frostbite or hypothermia or both. Prolonged exposure may be fatal.