A Winter Storm Watch, a Frost Advisory or a Wind Chill Warning—you've likely heard these winter weather alerts on your local news or as emergency notices sent to your cell phone. But where do these alerts come from and what do they mean? They come from Weather Forecast Offices (WFOs), sub-agencies of the National Weather Service (NWS) that cover every community in the United States. WFOs issue watches, warnings and advisories based on local weather forecasts and conditions.
What Do the Different Weather Alerts Mean?
The NWS breaks down weather events into three overarching categories: warnings, watches and advisories. Each of these categories has a specific winter weather alert as shown in the chart below:
||Frequent wind gusts of 35 mph or greater accompanied by falling and/or blowing snow with possible whiteout conditions. Visibility could be reduced to less than 1/4 mile for three hours or more.
||The potential exists for falling and/or blowing snow with strong winds and extremely poor visibility.
|Winter Storm Warning
||A significant winter weather event that could include snow, ice, sleet or blowing snow, or a combination.
|Winter Storm Watch
||Conditions are favorable for a significant winter storm event that could include heavy sleet, ice, heavy snow and blowing snow, or a combination.
|Winter Weather Advisory
||Snow, blowing snow, ice, sleet or a combination of these elements could occur, but conditions may not be hazardous enough to meet warning or watch criteria.
|Ice Storm Warning
||There's the possibility of 1/4 inch of ice to accumulate on the roadways, tree branches and power lines.
|Wind Chill Warning
||A combination of very cold air and strong winds may create dangerously low wind chill values. This could lead to frostbite and hypothermia if precautions are not taken when outside.
|Wind Chill Watch
||The potential exists for a combination of extremely cold air and strong winds that could create dangerously low wind chill values.
|Wind Chill Advisory
||Low wind chill temperatures are expected but may not reach local warning criteria.
||Significant, widespread freezing temperatures are expected.
||The potential exists for significant, widespread freezing temperatures within the next 24 to 36 hours.
||The minimum temperature is forecast to be 33 to 36 degrees and wind and sky cover may be favorable for frost development.
Check out this product guide to help prepare your people and facility for winter weather.