We've reached mid-September and have experienced all 4 season in the past 2.5 weeks. Where does that put us in terms of wildfire potential for the rest of the month?
In short, the rest of the month looks to be warm and dry with numerous dry cold fronts to bring us wind. To me, that spells enhanced fire potential.
Let's look at the precipitation we have received.
The past 30 days:
The past 7 days:
Over the past 30 days, most of the state has been drier than average. This time period does encompass our rain/snow event over Labor Day. It brought 1-2 inches of moisture to the central and northern Black Hills as well as portions of central SD. But since that time we have been exceptionally dry especially across western and southeastern portions of the state. The lack of recent precipitation tips the scales towards higher wildfire potential for the rest of the month.
The lack of precipitation has allowed the drought situation to continue. Over most of SD, drought is well-correlated to an increase in wildfires during September.
Looking ahead, dry and warm (actually hot) conditions are expected in both the short term and long term. The maps below are the current 6-10 day forecasts for temperature (top) and precipitation (bottom). This pattern continues for the
8-14 day outlook and the
3-4 week outlook.
Fuels are becoming even more available as the grasses become fully cured with the seasonal dry down. The grasses were struggling to begin with as the lack of moisture over the past few months has led to dry conditions. The Vegetation Drought Response Index (VegDRI) below shows how the drought has affect the vegetation.
The forecast weather models are showing an active pattern continuing through the rest of the month with several cool fronts (I'd call them cold fronts but the air won't really be that seasonally cold) moving through the state each week through the end of the month. Wildfires tend to grow big in September in the vicinity of a cold front. Remember, just ahead of an impending cold front temperatures are typically well above average with dry and gusty southwest winds. Then as the front passes, the temperature may drop but with dry cold fronts the RH tends to remain low as gusty northwest winds increase.
The highest wildfire potential remains over southwestern SD but the entire western half of the state has higher-than-average potential. East River areas are a mixed bag but with agriculture activities progressing, there will plenty of opportunity for new fire starts and a big fire or two cannot be ruled out.
But on the bright side, we may have some good opportunities for prescribed fire! Burn windows are short and the days with less wind may bring optimal RX conditions.
