All areas of Idaho are vulnerable to severe weather. A severe storm is an atmospheric disturbance that results in one or more of the following phenomena: strong winds and large hail, thunderstorms, tornados, rain, snow, or other mixed precipitation. Typically, major impacts from a severe storm are to transportation and loss of utilities.
The following severe storm elements are considered for this profile:
- High winds – Two types of significant wind hazards are possible in Idaho, straight line winds and tornadoes. Both are generally associated with severe thunderstorms.
- Severe Thunderstorm – Storms that produce winds of 58 mph or greater or three-quarter inch or larger hail.
- Tornado – A storm with a violently rotating column of air that contacts the ground; tornados usually develop from severe thunderstorms. Tornados can produce winds of 100 to 300 mph.
- Winter storm – Winter storms range widely in size, duration and intensity. These storms may impact a single community or a multi-state area. They may last hours or days. They may drop a small amount of dry snow or may blanket an area in wet snow and ice. Winter storms are generally characterized by low temperatures and snow.
- Blizzard – A storm with considerable falling and/or blowing snow combined with sustained winds or frequent gusts of 35 mph or greater that frequently reduces visibility to less than one-quarter mile.
- Dust storm – A storm of dust and debris blown by wind gusts of at least 35 mph, or caused by a downburst from a dry thunderstorm, that reduces visibility to less than one-quarter mile.