YUMA, Ariz. - U.S. Marines spend countless hours in extensive training outdoors. Oftentimes, the conditions of the weather can often lead to heat stress and exhaustion.
For that reason, the Marine Corps Air Station in Yuma uses a system that determines the days Yuma sees extreme temperatures.
Sgt. Jonathan Macdonald, a meteorological forecaster, said the system also measures the amount of outdoor activity Marines can handle.
"The black flag [warning system] is simply a step on the scale we use to indicate how much activity the marines can handle," Macdonald said. "It gives them an idea of what the heat is going to do to them."
They measure the black flag warning through what's know as the WBGTI thermometer. The scales of sevrity vary, they range from green, yellow, red and black flag.
A black flag warning signifies, "all strenuous, nonessential outdoor physical activity will be halted for all units."
Richard Barns, the Corps' tactical safety specialist said the fundamental purpose for the system is to highlight the heat stress conditions need to be mindful of.
"[There have] been a lot of heat casualties [before deployment,]" Barns said. "What we try to do is make them aware of what a heat injury looks like so they can take the appropriate action."