RedFlag Warning: This is a fire weather program which highlights the onset of critical weather conditions conducive to extensive wildfire occurrences.
A term used by fire-weather forecasters to call
attention to limited weather conditions of particular importance that
may result in extreme burning conditions. It is issued when it is an
on-going event or the fire weather forecaster has a high degree of
confidence that Red Flag criteria will occur within 24 hours of
issuance. Red Flag criteria occurs whenever a geographical area has been
in a dry spell for a week or two, or for a shorter period, if before
spring green-up or after fall color, and the National Fire Danger Rating
System (NFDRS) is high to extreme and the following forecast weather
parameters are forecasted to met:
I. A sustained wind average ]5 mph or greater,
2. Relative humidity less than or equal to 25%, and
3. A temperature of greater than 75°F.
In some states, dry lightning and unstable air are
criteria.
In Pennsylvania, the weather parameters are:
2. and
3. The 20 foot sustained winds are expected to exceed 15 mph (13 knots) for at least 2 hours
In the past, Pennsylvania has also used an independent parameter based on fuel moisture. This parameter may be reinstituted again.
It was:1, Ten hour fuels must be at 8% moisture or less and expected to remain at that level for 2 or more days.
Red Flag (Fire Weather) Watch is used to alert the user to the possible development of a Red Flag event in the near future. This could be up to 72 hours in advance.
see current Red Flag Warnings
