Why they call it a Red Flag Warning
AUSTIN (KXAN) — From time to time, in part of the spring and the fall seasons, Central Texas is affected by strong winds and low humidity. A cold front that blew through the area Saturday night left those weather conditions. Thus, a Red Flag Warning was issued.
Red Flag Warnings alert fire managers and other emergency service personnel on federal lands to those conditions that are highly unfavorable for prescribed burns.
So, what is the criteria? To start, ten-hour fuels of 8% or less. What does this mean? This describes how much water is held by small vegetation such as grass, leaves, and mulch that only takes about ten hours to respond to changes in dry/wet conditions. Boiled down, it simply takes a look at how much moisture there is in the ground.
The other two conditions are those that you hear KXAN Meteorologists speak about frequently during Red Flag Warnings. Start with the relative humidity dropping to under 25%, or lower, for several hours. The relative humidity tells forecasters and emergency management officials how much water there is in the air relative to the air temperature.
Last, wind speeds that are forecast at least 15 mph for several hours. Add to that those strong gusts that can, at times, exceed 35 to 40 mph, and you have the perfect setup for wildfires.
There are a couple of other contributors to this. One of them is a prolonged drought that increases the risk of wildfires all year. Because of this, fire danger can be high even when not in a typical season. Another is what is called dry lightning. This is when there are lightning strikes without significant rainfall.
When a Red Flag Warning is issued, emergency officials like the fire department and county heads urge citizens to be extremely careful and avoid outdoor burning. This is also taken care of by counties issuing outdoor burn bans. They also ask that if a fire does start, it be reported immediately to the local fire department.
So, why do they call it a Red Flag Warning? Red flags have been used historically to signal danger to the public. For example, when a railroad uses the red flag, it means stop immediately. A ship carrying munitions will be flying a red flag. So, it only makes sense that forecasters adopt the red flag to alert people to the imminent dangers that weather conditions bring that could start fires.
The Red Flag Warning has been used by the National Weather Service since the 1960s by fire weather forecasters with a two-fold purpose in mind. First, to protect our precious lands, and two, and most importantly, to save lives.
