The Fire Weather Episodes
of Winter 2005-06
Answer to Question 5
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5. It's now 11:30 am on February 28th. Examine the Oklahoma Fire Danger Model output for the most recent run.

  • Has the fire danger increased or decreased since 8:00 am? Why or why not?
  • What factors have changed on the weather map to increase the danger?

Now fast-forward to 3:30 pm. Examine the Oklahoma Fire Danger Model output for most recent run.
  • Has the fire danger increased or decreased since 11:30 am? Why or why not?
  • What factors have changed on the weather map to increase the danger?
  • What are the chances of a firebrand starting a reportable fire for most of Stephens County?
  • If a wildfire were to occur, about how tall would the flame at the head be?
  • If a wildfire were to occur, about how fast would it move?
  • If a wildfire were to occur, what direction would it move?
  • Can you see any wind shifts indicated in the Mesonet datasets?



Answer.

  • At 11:00 am:
    • The major fire danger indices had increased. This was due to the lower RH, stronger winds, and warmer temperature compared to 8:00 am.
  • At 3:00 pm:
    • The major fire danger indices had increased even more, for the same reasons.
    • The Ignition Component indicated a that, if a firebrand were released, there was a 38-49% chance that it would start a reportable fire.
    • The Burning Index across the western two-thirds of the county was in the 80-109 range, indicating expected flame lengths of about 8-11 feet. The table data for Ketchum Ranch indicated a value of 82 (8.2 ft).
      • In this range, the OK Fire Danger Model description says Fires may present serious control problems--torching out, crowning, and spotting. Control efforts at the fire head will probably be ineffective.
    • The Spread Component between 40-79 suggests that the forward speed of a wildfire would be between 40 and 80 feet per minute. The table data for Ketchum Ranch indicated a value of 64 feet per minute.
    • The Mesonet data indicate that a fire would move generally north. There is no indication of a major wind shift in teh region, as the dryline did not materialize (in the wind field). However, this should be monitored regularly in the event of a fire!

    • The Bottom Line:

    • The Oklahoma Fire Danger Model can give you a rough estimate of what you're up against, in the event of a fire.

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    Send comments or questions concerning OK-FIRST to okfirst@mesonet.org.