A storm in Nebraska produced an extremely rare pair of tornadoes this evening as it tracked through the northeastern part of the state. Multiple vortices are common in the strongest tornadoes (think Joplin), but two large, distinct tornadoes side-by-side like this is almost unprecedented.
Numerous storm chasers are reporting "catastrophic damage" and serious injuries as a result of the tornadoes.
Satellite tornadoes, where smaller, rope-like tornadoes circulate around a larger parent funnel, have been documented by spotters in the past, but it's hard to think of any time where we saw two independent tornadoes traveling side-by-side like this before. The Weather Channel's severe weather expert Dr. Greg Postel, filling in for Dr. Greg Forbes while he recovers from a round of chemotherapy this morning, says he's never seen or heard of a storm that's produced such a structure.
The only other storm I can think of that produced multiple independent tornadoes like these is the infamous supercell that spawned seven tornadoes in one night in Grand Island, Nebraska back in 1980 — the storm was the inspiration for the novel-turned-TV-movie The Night of the Twisters.
Reed Timmer was on the storm (of course) and he took this shot of damage left behind by one of the two twisters seen in the background.
Here's another shot of the twisters taken by Matt Coker:
For weather wonks, here's a screenshot I got of the radar while the twin tornadoes were on the ground. The circulations are visible in the white circles where the bright green and bright pink colors meet on the southwestern side of the storm.
Tornado watches continue across the central Plains and upper Midwest, with enhanced "particularly dangerous situation" (PDS) wording added by the Storm Prediction Center. A PDS watch is rarely issued and it's meant to convey the severity of the tornadoes expected.
[Video via The Weather Channel, images via Reed Timmer, Matt Coker, and RadarScope]
UPDATE: Thanks to bdrube in the comments for pointing out that one of the storms involved in the Palm Sunday tornado outbreak of 1965 produced twin tornadoes, as well.