BREAKING: We believe a tornado may have occurred on the rural north side of the Salt Lake City, Utah metro area. This is an extremely rare event. In fact, the radar signatures we're seeing are commensurate with storms that, historically, have produced EF2 or EF3+ tornadoes. This is truly an upper-echelon event, particularly for this region. Utah only averages 3 tornadoes per year – most of which are weak. The storm that occurred early Friday afternoon was a legitimate, mean supercell with a full-fledged Oklahoma-style hook echo. It also probably produced some large, damaging hail, perhaps upwards of golf ball size. Rotation was evident on the KMTX radar, located north of the Great Salt Lake, around 1:30 p.m. as the thunderstorm was beginning to work ashore east of the Lake. Rotation remained broad and diffuse until between 1:38 and 1:44 p.m., when it rapidly consolidated, tightening into a strong mesocyclone (rotating updraft) over Interstate 15 in Farmington. At this point, a funnel cloud was reported. We believe it probably had at least intermittent ground contact as a tornado. Then rotation tightened into a very strong circulation, and perhaps a significant tornado, as the storm passed over the mountains and canyon east of Farmington. Hikers on the Great Western Trail (Francis Peak to Morgan County) may notice a swath of trees down in the coming days from what may have legitimately been a strong tornado. Fortunately, the region appears sparsely-populated, and the probable tornado likely lifted before reaching Interstate 84. This may have been among the most impressive radar signatures ever seen in the state of Utah – nonetheless on a day when only a "marginal" severe weather risk was forecast. Let us know what you have been seeing! @MatthewCappucci's analysis: