The National Weather Service plans to issue a red flag warning of critical fire weather conditions including gusty winds and low relative humidity, effective Saturday evening through Sunday afternoon,

Red flag criteria is generally when relative humidity is at 15% or less, combined with sustained winds and/or gusts of 25 mph or greater. Both of these conditions must occur simultaneously for at least 3 hours in a 12 hour period, according to the NWS.

We've seen reports about Los Angeles County being under "fire weather watch" and "red flag warning." What is the difference?