Fire Classification

Copyright 2007. All Rights Reserved.

 

                                            Fire Danger Classification

The fire season in New Hampshire is usually from mid March through mid November. During the fire season New Hampshire weather data is collected daily from the National Weather Service in Taunton, Massachusetts and Gray, Maine, and from the system of fire tower lookout stations, and local fire departments with weather gathering instruments. This weather data allows us to determine daily forest fire danger to assist fire departments throughout the state with what might be expected for wildfire behavior.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

                 A class 1 day is a day a forest fire is not likely to start. (LOW)

                

                 A class 2 day the danger is MODERATE, but it is possible for fires to start in light flashy fuels but                   will have a slow rate of spread.

                 A class 3 day the fire danger is HIGH fine fuels in open areas and sunny slopes may spread rapidly.

                 A class 4 day the fire danger is VERY HIGH and fires will start easily from all causes. Fires will spread rapidly and increase in intensity rapidly meaning they will be hard to extinguish. Spot fires may occur and, except in spring, will burn deep.

                 A class 5 day the danger is EXTREME. Small fires will spread very rapidly meaning they will be hard to extinguish. Severe spotting may occur and mop-up will require a great deal of effort.

High Class 5: Fire behavior is extreme. Erratic winds, fire whirls, and spotting are a few of the many problems associated with fires. Containment may not be possible because of safety concerns. The fire may be causing updrafts and a large column or plume.

Fire Weather Watch
(possible "Red Flag Warning")

The National Weather Forecaster is near the "50% confidence level" that "Red Flag" conditions will occur within the next 12 hours.

Those conditions for vegetative Stage 1 and Stage 2 (cured and transition) are:

Wind......sustained or frequent gusts above 25 mph
RH..........less than 30%
Rainfall...less than 1/4" during the previous 5 or more days

Those conditions for Stage 3 (green) are:

Wind......sustained or frequent gusts above 25 mph
RH..........less than 30%
Rainfall...less than 1/4" during the previous 8 or more days
Fuels......Keetch Byram Drought Index is above 300

Red Flag Warning

The National Weather Forecaster is confident that "Red Flag" conditions will occur.

Not all of the conditions have to be met, just a majority of them.

 

                                  Copyright (c) State of New Hampshire, 2005