More Information about the Rangeland Fire Danger Index

 The following counties are currently included in an RFD or Grassland Fire Danger product:



Yellow = NWS Topeka
Blue = NWS Wichita
Green = NWS Hastings

Currently the Topeka RFD will have the Wichita RFD appended to the end, for better distribution to our users


Links to the full text products:
**NWS Wichita is producing an experimental Grassland index

What is the Rangeland Fire Danger Index and How is it calculated?

A series of tables is used to calculate the index.  The process is as follows:
  1. The first step is to compute the moisture content of dead fuels less than 1/4 inch, using temperature, RH and Sky Cover.
  2. Step two adjusts the 1 hour fuel moisture (found above) to account for reduced flammability of lesser fuels due to the presence of living herbaceous plant material. This information is gathered using satellite to estimate a "percent green".  Because it is collected via satellite, it is highly impacted by prolonged periods of clouds or snow cover, as well as by the amount of water vapor in the atmosphere.
  3. The third step relates the probability that a fire would result if a firebrand was introduced into the vegetative conditions found above.  It also considers sky cover and temperature.
  4. Lastly, the result is used in a table of wind speeds, considering a fuel model A (tallgrass prairie) and a slope class of 3 (40%), to arrive at the RFD index. 
As you can see, many variables can change the index  - particularly sky cover and temperature as they are used twice in the calculation. Also note this is customized to tallgrass prairie.

If you have questions about the changes or need more information, feel free to contact us using the contact information listed in the footer below.

 

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