Fire Season Outlook for the Western U.S

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)