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Fire Seasonal Outlook: Western U.S.
Nick NauslarPh. D. Candidate
Desert Research InstituteProgram for Climate, Ecosystem, and Fire Applications
Outline
• Seasonal fire outlook– Fire potential– What goes into it?
• Preview of the West’s fire season– Where will it be busy? – Official outlooks and my take
Fire Potential
• Conditions adequate to support fire ignition and spread
• Dry fuels necessary, BUT need fuels to burn…• Drought doesn’t always = increased wildfire
activity• Different climate and fuels create unique fire
regimes and thus need unique conditions• Similar to drought, these conditions occur on
multiple time scales (years to days)…need alignment
Alignment*
• Dry winter(s) -> dry fuels• Fine fuels don’t grow much, and thus limit
ability for continuous fuels and fire spread• But with heavy fuels (timber), crown fires
more likely (i.e. King and Rim fires) • Still need weather to cooperate (i.e. Nevada
last summer)
Wildfire Outlooks• Fire triangle • Fire outlook triangle: fuels,
weather/climate, typical fire season• Fuels
– Fuel dryness– Which fuels are dry– Fuel loading
• Weather/Climate– Drought– Snowpack– Monsoon/teleconnections
• Typical Fire Season– What are normal conditions?– Normal amount of fires, acres burned?
Typical Fire Seasons
Higher Elevations
Precipitation and Temperature
California Drought
Omegasaurus Rexblockus
Teleconnections
• ENSO: El Niño acts to suppress tropical activity, ITCZ pushes south, decrease in NAM precipitation
• PNA positive/meridional phase can enhance precipitation mostly during neutral ENSO
• MJO: can increase precipitation across western U.S. in phases 6-8
• Essentially…the development and location of the subtropical ridge
Recap of What to Look For
• Dry fuels• Fuel loading• Early green-up• Higher elevations/latitudes with ~average
precipitation, but below average snow/snowpack
• Forecast weather
May Outlook
June and July Outlook
Summary• Fire potential is more nuanced then just
‘drought = fire’• Fuels and atmosphere must align along
multiple timescales for increased or above average fire potential
• Earlier, longer fire season -> above normal fire season
• Potentially busy fire season for West Coast (California, Oregon, Washington)