The National Weather Service's Los Angeles page screams ''Particularly Dangerous Situation (PDS)'' in hot pink letters against a gray background.
It's a rare warning aimed at seizing attention ahead of extreme wildfire risk that's predicted to start in Southern California at 4 a.m. (1200GMT) Tuesday.
PDS warnings were first used to warn of tornado outbreaks in the Midwest. More than a decade ago, three meteorologists proposed expanding their use to disasters such as ice storms, floods, hurricanes, and now wildfires.
Grabbing attention
"It catches the attention, it really heightens that awareness and the need to really act at that point," said one of those scientists, Jonathan Howell.
The hope was that the phrase would ''become synonymous with extreme weather events'' and also could be used for emergencies such as hurricanes and snowstorms, Howell and two colleagues wrote for a presentation at a 2011 conference of the American Meteorological Society.
''I definitely think this has made an impact and has saved lives over the years," said Howell, who is the science and operations officer at the weather service's Mobile, Alabama office.
Past warnings