What is a Fire Weather Warning?
Posted October 5
Updated November 3
What is a Fire Weather Alert?
Mary Lee asks WRAL: What is a Fire Weather Alert, What does a Fire Weather Watch mean?
Mike Moss: There are a couple of fire-related advisories that may be issued by the National Weather Service, in conjunction with state and federal forestry officials. The more serious is called a Red Flag Warning, and is usually issued when a combination of three primary criteria will be exceeded all at the same time. Those three are: relative humidity less than or equal to 25 percent, sustained winds reaching 20 mph or more, and "10 hour fuels" (branches, twigs and so forth with diameters between one quarter inch and one inch) having a moisture content of 8% or less.
When these criteria are not met, but conditions are close enough to cause concern about outdoor fire behavior just the same, a Fire Weather Watch may be issued. In both cases, officials advise strongly against any deliberate outdoor burning and extra caution against accidental fires because of the potential for fires to rapidly spread and to become very difficult for firefighters to control or contain.
Search terms such as red flag warning, weather fire advisory, relative humidity, fire weather watch, fire weather warning, fire weather alert, fire weather bulletin, fire weather advisory, afire
Find more Weather and Science question and answers (Q&A) and info from the WRAL Weather team here.