Tuesday, June 27, 2017

Summary of the day: June 26, 2017

We started the morning in Kearney, NE, with our initial target of McCook, NE.  We had decided on a target area of eastern Colorado, northwest Kansas and southwest Nebraska.

Along the way, we noticed morning ACC (altocumulus castellanus), which is a good indicator of midlevel instability.  Also, when we were on the drive, we noticed (via RADAR and visually) some thunderstorms going to our north and northeast.

We decided to stop and have a look at the storms that were going on, as there was no other action going on in the region of interest.  It was clear that those storms were elevated, as the mushy appearance in real life and disorganized reflectivity on RADAR showed.

Storms still kept going and started to intensify generally to our north, all the while building westward along the slowly-advancing cold front.

At this point, 2 of the 3 vans lost their internet connections.  It made a chase day all the more difficult and stressful, but we managed.

One storm then began to dominate, one that was a little behind the initial broken line but still ahead of or along the cold front.  We decided to stay put and see what it would have to offer.

As we refined our location relative to it, we started to see some structure--a wall cloud, mostly.  Some good ventilation aloft was evident, as well.

The storm then quickly really became rather mean.  It showed us alternating low-level outflow and inflow structures, so we were in inflow at one moment and in outflow at another; the outflow was rather chilly and wet, but the southeasterly winds into the storm complex told us that the storm wasn't done.

We were stopping and taking pictures, then driving a little west as it surged more outflow south and a little west.  Eventually we came to a town where we could cross the Platte River and chase not just west but south.  This was a great option for us, as the southward reach of the storm was latitudinally equal to our location.  We got south and then got west just ahead of the outflow, hoping to see something good.  And see something good we did: we stopped just short of the best gustnado I've ever seen.  It was a long-lived compact vortex of wonder, awesomeness and dust.  It last for about a minute, maybe a bit more. Justin's video even got picked up by The Weather Channel.

After the gustnado, we were a little jazzed up but ready for more.  We got going west some more and We turned onto another road, a rained-on dirt road.  Not the best idea, as we immediately started sliding as though we were on ice.  Oy.  Justin stopped and we advised the other vans *not* to advance on this road.  Justin then put it in reverse and (rather heroically) inched backwards approximately 100 metres back to gravel.  There were a few times we were close to sliding off the road, but Justin kept that from happening.  (Thanks, Justin.)

The storm we had been watching (we in Chase 1 called him Gus) started to decay a bit--his outflow pushed way ahead of his inflow, and the updraft shrank considerably.  A beautiful hail shat was its last gift to us as we decided to move west to catch another storm.

This storm was another one westward along the line, but it decided to get outflowy too.

We went westward to an interesting-looking storm that was dropping south, one that was tucked well northwest of our location.  As soon as we saw it, though, we knew it was pretty special.
Boy, were we right.

We got a little closer to the storm and decided to take a dive south so we could see it better; a navigation error meant that we missed our turn-off and had to turn around.  Well, at the turn around near some grain silos, we stopped and got out to take some pictures.

This is where the storm decided to show us some great stuff.  The lazy low-level rotation tightened up really quickly.  It was strongly ingesting air, with help from some modified outflow from the storm to our southeast--it was raining into our updraft region.  I think that this storm was actually helped and hindered, simultaneously, by this rain.  It cooled (stabilized) the inflow region and moistened (destabilized) it, making sure the updraft base was lower.  It was ingesting surface-based parcels or near surface-based parcels, and the base looked to be below 1000 feet AGL.  then, the rotation got focused in one region and (I'm not kidding) we were all chanting "GO GO GO" at the storm; this was as close to producing a tornado as I've ever seen a storm be without actually producing.

After a while the low-level rotation weakened substantially but the broad-scale rotation was still good and so we decided to drop south with the storm, knowing that this was the storm to be on.

As we went south, it continued to show us HP and classic looks, with scary hail cores evident and then good updraft areas prominent.

We kept playing with the storm, as it was showing large to very large hail, so we stayed out of its core (for the most part).  We stayed back for a bit and tucked in behind the storm to see how big the hail was along the side of the road, and we got hail that was, at its largest, quarter-sized.  We notified the appropriate NWS office and went on our way.  Moving southward through the hailfall we encountered another neat phenomenon: hail fog.  It was pretty neat and eerie to see.

Finally running ahead of it, the storm decided to give us its last look.  It quickly morphed from a scary HP to a stunning LP supercell and it was so quick that I couldn't quite believe what I was seeing.  All of a sudden we were seeing striations and a huge separation of the updraft from the precipitation core.  At the same time RADAR was showing a marked increase in the hail size, despite it looking rather transparent visually.

A sheriff stopped to talk to us for a while.  He was extremely friendly and seemed to want to share his stories.

Eventually the LP structure started to decay, and it was time for us to get some fuel, both for our vehicles and for ourselves.  We stopped at a gas station where the storm gave us its last hurrah; it was severe-warned as it moved over us in Scott City, although the hail we eventually got at the gas station was about pea-sized, no more.  A little wind made the rain rather horizontal, and then that was the end of it.

Dinner was at a down-home place called Tate's; wonderful large portions of good food and friendly service.  I would recommend that any day of the week.

We had our overnight in McCook, NE, in eager anticipation of the next day.


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