Stagnation Index


The stagnation index is a number from 0 to 3 computed from forecast variables that are produced from a complex numerical model used by the National Weather Service.

The index takes the following parameters into account.

  1. Model Relative Humidity in the low levels.
  2. Model prediction of precipitation.
  3. Model prediction of Vertical Motion.
  4. Model prediction of Windspeed.

The index is used by Fire Managers ,who are cognizant of the need to occasionally restrict open burning in order to reduce atmospheric contaminants. Therefore, Managers use the index as part of the overall picture as input to issuing burning permits. A higher index correlates to greater stagnation.

Daytime:Scale of 0 - Burning permitted from sunrise to sunset.
........Scale of 1 - Burning permitted from 1 hour after sunrise until sunset.
........Scale of 2 - Burning permitted from 2 hours after sunrise until sunset.
........Scale of 3 - Burning permitted from 2 hours after sunrise until 1 hour before sunset.

Nighttime:Scale of 0 - Burning permitted from sunset to sunrise.
.........Scale of 1 - Burning permitted until 2 hours before sunrise.
.........Scale of 2 - Burning permitted until 4 hours after sunset.
.........Scale of 3 - No burning permitted.


Resulting Values

1. 0 Equates to winds of greater than 10 mph

2. 1 Equates to winds 10 mph or less with rain

3. 2 Dry with decent winds

4. 3 Dry with light winds and stagnate conditions



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