A long-track tornadic supercell moved across extreme northeast Montana yesterday evening, producing several tornadoes across this sparsely populated wheat country.  Sadly, two fatalities were reported west of Reserve, MT in Sheridan County from one particularly large and violent tornado produced by this storm.  Initially, two supercells developed around 23z in the vicinity of a triple point near the Saskatchewan Border, with the eastern storm becoming dominant later on as a dryline feature surged east along and south of an E-W oriented warm front.  The first cell likely produced before being cut-off from the instability by the surging dryline and/or RFD from the intensifying eastern cell.  This complex surface pattern can be seen in the two radar images below, showing both cells at 5:38 pm MDT, and the dominant eastern cell after the western one evaporated by 7:11 pm MDT.

A large, violent tornado touched down at around 6:15 pm MDT several miles west of Reserve, MT, and was reportedly on the ground for over a half hour, causing significant damage west of town.  A damage survey is scheduled for data by Glasgow NWS, and I wouldn't be surprised if we have another EF4 on our hands this season.  If I didn't have a dissertation to finish, I likely would have started this chase just north of the border in SK, so likely would have missed everything if the border crossing took too long.  I would seriously give any of our best chases this season just to be on this supercell from yesterday.  I'm obsessed with these subtle, late-season setups!!!  Once I finally graduate tornadoes like these will never again go un-chased..