Seasonal Outlook for December 2021 March 2022

[Pages:4]Seasonal Outlook for December 2021 ? March 2022

WEATHER/FUELS/FIRE POTENTIAL:

Over the last 30 days temperatures have remained above normal and precipitation has been well below normal across the Great Basin due to high pressure ridging in the west. The only exceptions were small areas of southern and eastern Idaho into Wyoming that were near normal. (Fig 1) ERCs have returned to above normal for the time of year due to the dry weather, but still would indicate low fire potential, especially due to the lack of fine fuels. The Evaporative Demand Drought Index (EDDI) indicated rapid drying over the southern third of the Great Basin over the last 3 weeks. (Fig 2)

The wetting rains from the surges of monsoon moisture and recent fall moisture in October have been nowhere near enough to alleviate the precipitation deficit across the Great Basin. Extreme to exceptional drought continues across the southern two thirds of the Great Basin and over central Idaho. Exceptions are over parts of southwest and eastern Idaho, Wyoming, northern Nevada, southwest Utah and the Arizona Strip where the drought has improved to moderate to severe. The drought is likely to persist through the next few months in most areas of the southern half of the Great Basin but there may be some improvements over the northern third of the region as fall and winter cold fronts bring additional moisture more consistently than areas further south due to the presence of La Nina. (Fig 3) Soil moisture is near normal and the snowpack has dropped back down to below normal region wide due to recent dry conditions. (Fig 4 and 5)

WEATHER/FUELS (cont.) Fine fuel loading was lower this year as compared to recent years across much of the Great Basin due to low elevation snowfall and poor green-up earlier in 2021. Most areas saw a poor green-up this year with minimal new fine fuel growth due to the drought, although parts of northern Nevada saw some growth due to late spring precipitation. The lack of fine fuels will minimize the threat for fall/winter cold frontal wind driven fires in the lowest elevations even after significant dry periods. However, very wet weather in October may help to deeply moisten the soils and lay the groundwork for an increase in fine fuel growth in the spring, depending on precipitation over the next few months. This will be monitored as we head toward the fire season in 2022.

Warm and dry weather is expected heading into the first one to two weeks in December. However, a pattern change is likely by mid to late month which should bring cooler weather and some precipitation chances. The focus for wetter weather later in December and January will likely be across the northern half of the Great Basin but may push further south heading into February. (Fig 6)

FIRE POTENTIAL

Normal fire potential is expected through February, which would be generally low. There could be upticks in fire activity on windy days after prolonged dry periods. However, these periods would be brief, and not as concerning as years where there is more an abundance of fine fuels.

Fig 1. (30-day Temperature / Precipitation)

Fig 2. (Current EDDI)

Fig 3. (Drought)

Fig 4. (Snowpack)

5Fig 5 (Soil Moisture)

Fig Fig 6. (PS 4 Month Weather Outlook)

Gina McGuire Palma Meteorologist - Predictive Services Great Basin Coordination Center, Salt Lake City UT

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