When is a red flag warning typically issued for severe fire weather events?

A red flag warning is issued to indicate the presence of critical fire weather conditions that can lead to the rapid spread of wildfires. This warning is generally issued when forecasters identify a high potential for significant fire activity due to factors such as high winds, low humidity, and dry vegetation. The key aspect of the issuance timing reflects the immediacy of the threat; specifically, red flag warnings are typically issued when critical conditions are expected to develop within a timeframe of less than 12 hours. This provides emergency services, wildland firefighters, and the general public time to prepare for the imminent fire risk and take preventative measures. Thus, the choice indicating a notification of less than 12 hours aligns perfectly with the standard operating procedures for issuing such warnings in the context of severe fire weather.