Winter Weather Terminology
A storm that produces heavy snow and/or significant ice accumulation.
A blizzard means that the following conditions are expected to prevail for a period of 3 hours or longer:
- Sustained wind or frequent gusts to 35 miles an hour or greater; and
- Considerable falling and/or blowing snow (i.e., reducing visibility frequently to less than 0.25 mile)
Lake Effect Snow
Snow showers that are created when cold, dry air passes over a large warmer lake, such as one of the Great Lakes, and picks up moisture.
Increased wind speeds accelerate heat loss from exposed skin. No specific rules exist for determining when wind chill becomes dangerous. As a general rule, the threshold for potentially dangerous wind chill conditions is about -20°F (-29°C).
An ice storm is used to describe occasions when damaging accumulations of ice are expected during freezing rain situations. Significant accumulations of ice pull down trees and utility lines resulting in loss of power and communication. These accumulations of ice make walking and driving extremely dangerous. Significant ice accumulations are usually accumulations of 0.25 inches or greater.
Watches, Warnings, and Advisories
Winter Weather Advisory
Issued when a winter storm produces a combination of winter weather (snow, freezing rain, sleet, etc.) that present a hazard, but does not meet warning criteria.
Winter Storm Watch
Issued when there is a potential for heavy snow or significant ice accumulations, usually at least 24 to 36 hours in advance.
Winter Storm Warning
Issued when a winter storm is producing or is forecast to produce heavy snow or significant ice accumulations.
Issued for winter storms with sustained or frequent winds of 35 mph or higher with considerable falling and/or blowing snow that frequently reduces visibility to 1/4 of a mile or less. These conditions are expected to prevail for a minimum of 3 hours.
Wind Chill Advisory
The wind chill could be life threatening if action is not taken.
Wind Chill Warning
The wind chill is life threatening.
Snow and Blowing Snow Advisory
Issued when wind driven snow reduces surface visibility, possibly, hampering traveling. Blowing snow may be falling snow, or snow that has already accumulated but is picked up and blown by strong winds.
Lake Effect Snow Advisory/Warning
When lake effect snow may pose a hazard or is life threatening.
Ice Storm Warning
Freezing rain will produce a significant and possibly damaging accumulation of ice. The criteria for this warning varies from state to state, but typically will be issued any time more than 1/4" of ice is expected to accumulate in an area.
Issued during the growing season when surface temperatures are expected to drop below freezing over a large area for an extended period of time, regardless whether or not frost develops.