May 282013

Moisture (humidity) Convergence at 5 pm

Moisture (humidity) Convergence at 5 pm

The chasing tour went out to Kansas on Memorial Day.  My choice for developing storms didn’t pan out as well as areas north of our position.

First off, we were treated to some awesome turbulent eddies on the underside of a cold outflow boundary in western Missouri along highway 7.

We traveled up to Kansas City and then west along I-70. We ended up on the southern end of tornado watch which was hoisted for northern Kansas and southern Nebraska.

The key meteorological players in this chase were the dry line, an old cool air boundary and an upper level storm coming out of Colorado.

Turbulent Clouds Above a Cold Outflow of Air

Turbulent Clouds Above a Cold Outflow of Air

Chasing is full of decisions.  One of them often is: do we need to travel farther or is where we are just fine?  If this particular tour was un-tethered (meaning we could spend the night) the distance from Springfield is not much of an issue.  But for tours requiring coming back the same day, distance plays a factor.  Here’s what happened.

The combination of low level wind shear and unstable air was extreme across a large area of central Kansas, curling northwestward into Nebraska and even portions of Colorado.

This was out ahead of a dry line. The dry line is a major player in the development of severe storms in the Great Plains.  This line was moving eastward and was producing a great deal of converging, unstable air. (largest blue bulls-eye on map)  We eventually ended up around Ellsworth, KS which is just southeast of Russell. (in the bulls-eye).  All parameters looked good.  Towers (tall cumulus clouds wanting to be storms) were visible from our location. As radar looked better we literally moseyed along, staying  ahead of the developing cells.

Now, rewind just a bit because a discussion did occur about the merits of travelling north to near the Nebraska border to chase.  This would have been closer to the center of the eventual tornado watch.  But everything looked nearly perfect where we were, so we stayed put.

I say this because as it turns out, a supercell did travel out of Nebraska and into extreme northern Kansas. This tornado was captured near Cora, Kansas by the seemingly fearless (and armored!) Reed Timmer and troop.  I included the video below. While we were staying ahead of the storms we decided to chase, a tight rotation could be seen on this  northern storm. However, it looked severely wrapped in rain (video shows this) and therefore only someone willing to be right on top of it would see anything.  That is something my tours will never do!

After following the storms of choice it was starting to become clear they weren’t organizing. It appeared to be a combination of warm air aloft coupled with slightly less overall shear. This meant storms were being forced from below but needed continuous forcing to keep going. Also lack of great shear lead to multicell clusters rather than supercell storms.

The low level rotation was however quite good which lead to shots like the ones I included in the video: hints of low level rotation but no supporting, sustained updrafts above.

As a chaser, I’d love to see a tornado every time. But the goal of chasing with me is to learn about what makes severe storms, why they form where they do and why sometimes they don’t.  Seeing a tornado is a treat when storm chasing; it is certainly not a guarantee. Especially when additional non-meteorological considerations of safety and distance are thrown in.

Here are some videos:

Amazing Video from Inside this Tornado from Sean Casey and the TIV

Reed Timmer in the Dominator

My Review From the Road of the Chase