September 03, 2017 Severe Storm


A cold front was predicted to sag southward, and the models showed some reasonably good vertical wind shear over the area.  The NAM nest model (a convection-resolving model) also showed some updraft helicity swaths over Itasca County.  However, the convection-resolving models also tend to be a bit aggressive in the strength of their storms. Often, the storms don't even develop.

Deer River Storm
NAM next forecast some pretty significant updraft helicity tracks.

Indeed, as the evening began, the storms that were supposed to be to my north and a bit farther to my west had not developed.  When the sun set and the cold front was approaching, I decided to take a walk through the neighborhood to an open spot so I could see if there were even any boundary layer-based cumulus clouds along the cold front.

I walked a couple blocks until I could see to the west, and to my surprise, I saw a pretty tall cumuloform tower, but then a rather stratiform cloud base moved in underneath it, and I second-guessed whether I had interpreted what I saw correctly.  Finally out in a more open area, I saw that it did look like the it was developing an anvil with an updraft to the west of me.

Deer River Storm
Towers going up, viewed from my neighborhood.

Then, I remembered that I had my phone with me, and I could check radar.  Lo and behold, it showed the first echoes from this developing convection.  I started back home (about a five block walk), and just as I did, a couple flashes of lightning illuminated the sky to my west.  By the time I had walked another three blocks, there was frequent lightning to my west.  This strong storm had developed from nothing in about ten or fifteen minutes.

I set up a camera in my garage and began to take video of the lightning. Well, the video I took really isn't all that impressive.  In fact, it's pretty boring compared to most storm chase video nowadays, but it was fun to bt there.

Deer River Storm
A CG visible from my garage.

After the storm passed my house, the national weather service put out a severe thunderstorm warning for it, and the shape started to look pretty interesting on radar, so I decided to chase it. The chase effort ended up being rather futile because the storm was moving pretty fast, and there were a lot of clouds behind it, so I never saw anything photogenic. Plus, it's hard to identify many storm features when you're driving through trees at night. When I got to Jacobson and saw that the storm was not really evolving into a supercell, I turned back for home.

Deer River Storm
Route to Jacobson and back.

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