Red Flag Warning (Burn Ban) vs. Fire Danger
What makes Platte Canyon Fire Protection District go into a Burn Ban? A red flag warning! Below is the National Weather Services definition of a red flag warning and what the weather has to be like to have a red flag warning.
Red Flag Warning
Informs land management agencies of the imminent or actual occurrence of Red Flag conditions. A Red Flag Warning will be issued when there is high confidence that Red Flag criteria will be met within the next 24 to 48 hours, or when those criteria are already being met or exceeded. A warning may be issued for all, or portions of a fire weather zone or region (Platte Canyon Fire District is in zone 216). Zones impacted by the event will be listed within the Red Flag Warning product.
A combination of weather and fuels conditions (as determined by fire management) for any 3 hours or more in a 12 hour period. These criteria for the forecast area of the Denver/Boulder NWS office are defined as the following:
1. Frequent gusts of 25 mph or greater – AND relative humidity of 15% or less
2. Dry thunderstorms (15% coverage or more, constituting an LAL 6.)
In addition to the basic criteria above, a combination of other elements may result in Red Flag Conditions:
3. Haines Index (humidity in the air) of 5 or 6, indicating a moderate or high potential for large, plume dominated fire growth.
4. Wind shifts associated with frontal passages.
5. First significant lightning event (wet or dry) after an extended hot and dry period.
6. Poor relative humidity recovery overnight (RH remains at 40% or lower.)
7. Any combination of weather and fuel moisture conditions which, in the judgment of the forecaster, would cause extensive wildfire occurrences.
If a fire was to occur on a red flag day, it would be very difficult to suppress, the fuels are ready to burn and just need an ignition source.
Fire Danger Ratings, what we see on our Smokey Bear signs, are determined by the National Fire Danger Rating System coming from the Pueblo Interagency Dispatch Center.
For Very High Fire Danger, but not Red Flag, or in other words, No Burn Ban is in effect is when the above criteria from the National Weather Service does not have all of the criteria met to be in a Red Flag Warning. Basically, the weather we have seen in our district from August 15, 2019 through today August 20th, hot, dry, and windy.