After sitting down to view videos from yesterday’s chase of non-severe storms I’ve concluded that, yes indeed, I did witness a wall cloud formation. Here’s a still photo of said feature:
At the time I was hesitant to label this a wall cloud given a decided lack of deep layer shear in the overall setup. However after examining the evidence I’ve concluded that local factors (i.e. an outflow boundary from another storm) provided the necessary low level shear. A significant part of that evidence came from tree damage in the Chamblissburg VA vicinity that temporarily blocked VA Route 24.
First, a geographic reference. Here’s a screen shot showing my location vs where the tree damage and road blockage occurred:
The photograph was taken looking slightly west of due north (call it 350 degrees). Now, here’s a radar reflectivity grab 5–10 minutes before the wall cloud formed:
I had watched the convective line east of my location in this radar frame from a couple of other locations before stopping here. During a brief stop at Staunton River High School I noticed low level clouds pushing west from this activity. Thus I suspect that an outflow boundary from that storm interacted with the cell developing to my north in the radar scene.
Here are two radar VIL grabs showing intense precipitation – and probable hail – just to my northwest over the Chamblissburg area during or shortly after the wall cloud formation:
This certainly looked strong enough to have caused the tree damage in that area. In addition I noticed the next VIL radar sweep (which I didn’t save) showed a much diminished signature, indicating that the core of the storm had collapsed over Chamblissburg. That would go hand in hand with the wall cloud morphing into a linear shape, becoming an outflow-dominant shelf cloud as I watched it.
For the final piece of evidence the video of the wall cloud (sped up 8x) can be found here. The rotation is obvious and the development of a tail cloud back toward the precipitation shaft also lends credence to this being a wall cloud.
Yeah, I’m a weather geek as well as a storm chaser…