The Fire Weather Episodes
of Winter 2005-06
Answer to Question 3
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3. You decide to check the SPC fire weather outlook in the OK-FIRST Choose Your Threat Fires section:

  • What are the ingredients that are mentioned for the increased fire danger?
  • What are some surface features that may play a role in wind shifts today?
  • What are the expected reletive humidity values in your part of Oklahoma today?


Answer.

  • Four ingredients are spelled out in the discussion: PRIMARY CONDITIONS: VERY WARM TEMPERATURES / LOW RH / MDT SWLY WINDS / DROUGHT
    • Relative Humidity: RH is the most critical fire weather parameter. At very low RHs, dead fuels dry rapidly.
    • Moderate southwesterly winds: Winds also play a role in drying fuels and in propagating fires once they are started.
    • Very warm temperatures: Increasing the temperature adds to the fire danger put in place by RH and wind conditions.
    • Drought: When the soils are very dry, organic matter in the top few inches can actually burn in the fire. This makes for hotter fires that are harder to extinguish.
  • The map shows a dry line analyzed in the Texas and Oklahoma panhandles. This may be a feature to keep an eye on should fires develop.
  • The SPC discussion mentions that RHs are expected to be in the 20-25 percent range this afternoon.

    • The Bottom Line:

      Nothing prepares you for the hazards of the day like a thorough self-briefing.

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