Winter is just around the corner. When a warning is issued, will you know what it means and will you know how to respond? During this Colorado Winter Weather Prepared-ness Week, review the list of winter weather products, as well as warning and advisory criteria.
This list contains the warning and advisory criteria for Colorado west of the continental divide.
A hazardous weather outlook is issued daily by each National Weather Service office in Colorado. The outlook provides information on potentially hazardous weather out to seven days into the future. Also, the weather story — a graphic of expected hazardous weather is posted daily on National Weather Service websites serving Colorado.
WATCHES AND WARNINGS
A winter storm watch is issued when hazardous winter storm conditions are possible, but not certain, within the next 12 to 48 hours. For rare situations a watch can be issued beyond 48 hours into the future.
In contrast, winter weather warnings are issued when potentially life-threatening weather events are likely to occur.
A winter storm warning is issued for the occurrence of heavy snow or any combination of heavy snow and other events. Other events include such things as blowing snow or very cold wind chill temperatures.
Warning criteria for heavy snow is defined by the following amounts.
In the mountains — 12 inches or more per storm event.
At lower elevations — six inches or more per storm event.
Or an early season or late season snowfall having a significant impact but not meeting the above criteria.
A blizzard warning is issued when the following conditions are expected to persist for at least three hours:
Sustained winds of 35 mph or greater and considerable falling and/or drifting snow lowering visibilities to less than one-quarter mile.
A high wind warning is issued for the following conditions:
Mountains — sustained winds of 50 mph or more for at least one hour or gusts of at least 75 mph for any duration.
Lower elevations — sustained winds of 40 mph or more for at least one hour, or gusts of at least 58 mph for any duration.
A wind chill warning will be issued for the following wind chill temperatures.
Mountains — minus 35 degrees Fahrenheit or colder.
Lower elevations — minus 25 degrees Fahrenheit or colder
Advisories for winter weather are issued for potentially hazardous conditions.
Advisory criteria for snowfall is defined by the following amounts:
Mountains — five to 12 inches per storm event.
Lower elevations — three to six inches per storm event.
A wind chill advisory is issued when wind chills at lower elevations are expected to be between 15 below and 24 below zero and in the mountains for wind chills between 25 below and 34 below zero.
A dense fog advisory is issued for fog reducing visibility to one-quarter mile or less.