National Weather Service United States Department of Commerce
THIS VERSION IS NOT THE LATEST.  Please update your bookmarks to

November 25, 2019 Update. Improved filter and counter functionality.
load Loading...

Fire Weather Snooper


Back to Tables

Snooper Help

  Training Presentation
What is the Severity Index?
The severity index is an attempt to boil down the important fire weather parameters into a single value. It is tuned such that it generally falls between 0 and 100, such that 30 is a typical number for a significant observation and 100 is about as bad as it gets.
This is primarily intended to help filter the display of stations to only the weather significant ones, which is useful for networks with hundreds of stations.
The equation for the Severity Index (SI) is: Wind + 0.75*(50-RH) + 0.50*(T-70)
Where: Wind = Highest speed between the sustained and gust. RH = Relative Humidity. T = Temperature
The lowest any of the 3 terms (Wind, 0.75*(50-RH), 0.50*(T-70)) can be is -20. The lowest the SI can be is 0.
What does a "Red Flag" station mean?
A "Red Flag" station means that the observation is hitting Red Flag criteria. These criteria are locally set by the responsible NWS office, and vary by each office. Red Flag conditions generally mean that the weather is favorable for dangerous fire growth and behavior. Other factors are important in assessing the fire growth and behavior risk, including the moisture in the live and dead vegetation (fuels). If the weather is hitting Red Flag criteria, but the fuel moisture is high, the fire growth risk is greately minimized.
What does a "Flirting" station mean?
A "Flirting" station means that the observation is not hitting Red Flag criteria, but it is close. If the wind is within 5 mph and the humidity is within 5% of criteria, it is considered "Flirting"
What does "Duration" mean?
The "Duration" value contains two numbers. The first number is how many hours in the last 24 that the station has hit Red Flag Criteria. The second number is how many hours in the last 24 that the station has hit Red Flag Criteria OR flirted with it.
What does "Fuel" mean?
The "Fuel" observation value is an approximate moisture content for dead vegetation (fuels) with diameter of 0.25 to 1.00 inches. This would include things like twigs and small branches. Fuel moisture sensors are only available for select stations (RAWS type). The value is the percent weight of water in the fuel compared to the dry fuel weight.
Can I narrow the list of stations to specific counties, zones, or station ID's?
Yes! A user interface is currently being developed to make this easier, but the functionality exists through the actual URL link. Use the following examples as a guide to tune the display to your needs. If you need help please reach out:
Can I just show red flag stations?
Yes! There is a filter in the option menu, or you can add "&rfonly=1" to the URL for only Red Flag stations, or "&rfonly=2" for only Red Flag and Flirting stations.
  • (Normal)
  • (Red Flag and Flirting Only)

    NOTE: Which red flag criteria is used is set by the location of each individual station.
    If you would like your office's red flag criteria added, please email:
    Offices currently configured: lox,sgx,fgz,psr,twc,bou,sjt,tbw,unr,mtr,gsp,hnx,sto,pih,rev,otx,vef,gyx,eka,mfr,lsx,lbf,ffc,rah,jax,car,pqr,riw,dmx,phi,mrx,pdt