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Severe Weather 2026

Trey on the case:


Go Dark Helmet GIF
 
That was a potentially EF3+ intensity tornado in Utah. @N0mz I'm calling you because orographic influence absolutely had something to do with this one.



Just to put this into perspective, this is likely the first time a 80+ kt VROT couplet has been recorded this far West in the US and was also likely a major tornado. Utah hasn't seen a tornado like this intensity wise since potentially 1993. Wow.

Supercell tornadogenesis coming down the lee side of a mountain is textbook orographic influence. See this figure from
Bosart et al. 2006, where vrot quickly increases on the Great Barrington 1995 supercell after coming down the lee side of a mountain. The quickly dropping elevation forces the mesocyclone to stretch vertically, constricting the diameter of the mesocyclone. Due to the conservation of angular momentum, this increases the rotational velocity, much like a figure skater pulling their arms in.
1789777310613.png

Another orographic note: I noticed this persistent area of reflectivity on radar in the area, unrelated to precipitation or any gust front. I assume this is valley channeling caused by Farmington Canyon, which shows up on radar since bugs and other particles get stuck in the valley. Valley channeling, especially in north-south oriented valleys, can locally increase moisture and vorticity by literally channeling air mass up the valley, allowing a relatively tame supercell to produce a damaging tornado.
Screenshot 2026-09-18 at 8.25.18 PM.png1789777832819.png

I recommend watching June First's video on the Great Barrington tornado, which explains both of the above orographic phenomena with good visuals.
 
Supercell tornadogenesis coming down the lee side of a mountain is textbook orographic influence. See this figure from
Bosart et al. 2006, where vrot quickly increases on the Great Barrington 1995 supercell after coming down the lee side of a mountain. The quickly dropping elevation forces the mesocyclone to stretch vertically, constricting the diameter of the mesocyclone. Due to the conservation of angular momentum, this increases the rotational velocity, much like a figure skater pulling their arms in.
View attachment 55015

Another orographic note: I noticed this persistent area of reflectivity on radar in the area, unrelated to precipitation or any gust front. I assume this is valley channeling caused by Farmington Canyon, which shows up on radar since bugs and other particles get stuck in the valley. Valley channeling, especially in north-south oriented valleys, can locally increase moisture and vorticity by literally channeling air mass up the valley, allowing a relatively tame supercell to produce a damaging tornado.
View attachment 55016View attachment 55018

I recommend watching June First's video on the Great Barrington tornado, which explains both of the above orographic phenomena with good visuals.


I think this is interaction also happened with 1985 Moshannon multiple times. That one has a super interesting damage path.
 
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