AUSTIN (KXAN) – From time to time, for part of the spring and fall, Central Texas is hit by strong winds and low humidity. The cold front that moved into the area Saturday night left those weather conditions behind. Thus, a red flag warning was issued.
Red flag warnings alert fire managers and other emergency services personnel on federal lands to those conditions that are highly unfavorable for prescribed burns.
So, what are the standards? To start, fuel for ten hours at 8% or less. What does this mean? This describes the amount of water held by small plants such as grass, foliage and mulch which only takes about ten hours to respond to changes in dry/wet conditions. When it boils, it simply takes a look at how much moisture is in the ground.
The other two conditions are ones you hear KXAN meteorologists talk about frequently during red flag warnings. Start with the relative humidity below 25% or lower for several hours. Relative humidity tells forecasters and emergency management officials how much water is in the air relative to the air temperature.
Finally, winds are expected to reach at least 15 mph for several hours. Add to that those powerful gusts that can sometimes exceed 35 to 40 miles per hour, and you have the perfect setup for a wildfire.
There are two other contributors to this. One is the prolonged drought that increases the risk of wildfires throughout the year. For this reason, fire danger may be high even during non-normal seasons. The other is what is called dry lightning. This happens when there are lightning strikes without heavy rain.
When a red flag warning is issued, emergency officials such as the fire department and county sheriffs urge citizens to be extremely cautious and avoid open burning. This is also being taken care of by counties issuing open burning bans. They also ask that in the event of a fire, the local fire department must be notified immediately.
So why do they call it a red flag warning? Red flags have historically been used to indicate danger to the public. For example, when a railway uses a red flag, it means to stop immediately. A ship carrying munitions will raise a red flag. So, it makes sense for forecasters to adopt the red flag to alert people to the impending dangers brought by weather conditions that could lead to fire outbreaks.
The Red Flag Warning has been used by the National Weather Service since the 1960s by fire weather forecasters with a dual purpose in mind. Firstly, protecting our precious lands, and secondly, and most importantly, saving lives.