Hot, dry, and windy on Thursday, 9/26/19

Highlights:

Near-critical fire weather conditions are possible over southwestern SD tomorrow. A strong cold front will then move through tomorrow evening.

Discussion:

We are expecting a hot, dry, and breezy day tomorrow across Fall River, Custer, and Oglala Lakota Counties. Temperatures are expected to reach the mid-80s, minimum RH will drop into the 13-20% range, and west-southwest winds from 10-20 mph are likely with gusts to 30 mph possible. 

A dry cold front will then move through the state tomorrow evening. This will bring a period of breezy northwest winds, gusting to 20-35 mph over southwestern SD. Keep this evening wind shift in the forefront of your mind if there is an ignition. Cooler and more humid conditions will prevail on Friday with the breezy northwest winds continuing through midday. Showers are expected Friday night and Saturday.

Fuel conditions are not yet critical but the Cottonwood Creek fire last week (9/17) did grow to 57.54 acres showing that there is some potential for fire growth in that area of the state. Quoting Jay Wickham from Monday’s Weekly Weather Update, “There are some areas in the southern Black Hills where the grass has cured but most of the herbaceous vegetation will probably remain green until we receive some hard frost.  Wind will be the driving factor for any fire to be able to spread.” The neighboring counties in WY are under a Fire Weather Watch for Thursday but no Fire Weather Watches or Red Flag Warnings have been issued by the NWS for areas of SD as of yet. 

Lightning today and tonight

Showers and thunderstorms are moving through portions of the Pine Ridge Reservation. Additional showers and thunderstorms are now moving into western SD from WY. These storms are moving quickly to the north-northeast, are producing frequent lightning and gusty winds, but are not putting down much in the way of rain. I expect these storms to continue through the evening.

The fuels are not yet favorable for large wildfire growth but it wouldn’t surprise me to see several ignitions from this event. Watch for holdovers in the coming days as well.