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This was taken at 1701 MDT looking NW at an extensive anvil blowing off into Canada. The main updraft is well to the left of this photo and there wasn't much visible thanks to all the foreground Cu. On the right is a visible satellite image with sfc obs from about this time. |
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A few hours prior,
it looked reasonable that Glasgow would fall in the path of this supercell...especially
considering this storm had maintained such a persistent SE motion.
The time here was 1746 MDT and it was readily obvious the town was in danger.
Thankfully, warnings were out well in advance of this.
On radar, the supercell had already transitioned into a DCZ structure. This photo is looking SW at the apex of the bow echo while the meso resides just off the picture and to the right. |
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I thought for sure I'd see some
kind of mesocyclonic structure, but it wasn't that simple. This
is looking west directly at the radar indicated meso rotation along and
to the north of the DCZ. Also, the sky really was this deep aquarmarine shown here--no post-processing trickery.
About 15 minutes before this photo, the ASOS measured a 62 mph inflow gust directly out of the east! Thankfully the bow echo structure passed south of Glasgow where a spotter measured an 89 mph outflow gust. 1751 MDT |
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I've seen some downright
evil looking shelf clouds before, but the color of this one alone was enough
to make my stomach churn!
1752 MDT |
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There wasn't much outflow at the
office given the meso tracked directly overhead, but hail up to 2" was
falling at this time with some 3" stones farther south. There's nothing
I hate more than getting hail dents on my car when I'm not even chasing!
1802 MDT |
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The large hail didn't
last too long, but was followed by a barrage of smaller stones with intense
rains. Here's a hail drift at the office after the storm.
1822 MDT |
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0.5° tilt history of this supercell.
It's worth noting that the mean storm motion this day was NEerly, so despite
its deceptive transition into a linear structure near GGW it maintained
a deviant track for nearly 10 hours thanks to the deep mesocyclone.
Finally, I need to nix some rumors that the ND hail suppression ops "killed" this supercell on the MT/ND border. This supercell had been dissipating well before it neared the border and this was clearly reinforced by the limited instability farther east by mid evening. Hail suppression does not eliminate a storm. Rather, it simply attempts to limit hail growth. |
All
photos © Copyright 2007 Matt Ziebell
