Record to near-record high temperatures are expected over much of western and southern SD on Tuesday, Dec. 22. These "hot" temperatures will occur just ahead of a strong cold front that will push through western SD tomorrow afternoon and evening. Historically, this is a classic fire weather setup for the western half of the state.
High temperature and wind direction:
Furthermore, the wind will be strong ahead of the cold front. Potentially very strong. Gusts could definitely be in the 30-50 mph range, maybe even higher.
Winds:
As it is winter, there isn't a lot of moisture around. Thus low RHs will accompany these warm temperatures. Often, we think of critically low RH as those less than 15%, but in the winter I get concerned when the RH is below 35%. (But I think we could get close to the 15% range anyhow.)
Minimum RH:
And it has been dry. We just haven't been getting widespread precipitation. Below is the total precipitation for the last 30 days. Note how much of the state has been completely dry!
This is going to be an evolving threat through the day and the forecast images above only show conditions for 2:00 pm MST tomorrow. But know that southerly to southwesterly winds are expected during the morning, these will transition to more westerly winds in the mid afternoon. The cold front will then push through tomorrow afternoon bringing strong northwesterly winds. If a wildfire does occur, be sure to remember the wind will likely shift dramatically as the front moves through.
Oh and don't forget that the strong northwest winds will persist on Wednesday, albeit with colder temperatures in the post-frontal environment. Some upslope-induced snow is expected over the northern Black Hills late on Tuesday and through Wednesday but the show will likely be limited to just that area.
In summary, my concern is growing for the potential of critical fire weather conditions across all of western and southern SD over the next 36 hours.
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