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Lesson reemphasized: Never underestimate the potential of a less-than-desirable convective setup.

With an upper level low moving toward Virginia yesterday – Thursday 4/30 – the accompanying cold pool aloft looked like a sure trigger for storms with small hail. Although the CAPE looked puny (500 j/kg max model values) and both low level & deep layer shear were pretty much non-existent I was certain conditions were ripe for chaseable but non-severe storms.

Accordingly I haunted the short range models during the morning hours. The HRRR (and to a lesser extent the RAP) model showed convective cells reaching the U.S. Route 29 corridor by 2 pm. However since the simulated radar on the HRRR wasn’t matching up with the morning real-time radar in southern Virginia I dismissed the early afternoon potential and counted on the later action as the upper low got closer.

Thus I left home at 1:30 as a decent storm dropped rain and hail on the southern Roanoke valley. Sure enough convection had popped up where and when the HRRR had predicted and I was behind the eight ball. To miss the local cell I wound my way out of the valley across ridgelines to Burnt Chimney and then continued south along rural roads to VA Rte 40.

Stopping in Penhook to fill the gas tank I took note of a significant line of storms to the south, with the strongest activity heading east toward the Danville area. Once I reached Rte 29 at Gretna I sped south in hopes of reaching Danville ahead of this slowly moving line. I made it – barely – and motored east on U.S. Route 58 to find a spot to stop and watch.

I found a vantage point a couple miles south of Rte 58 and positioned the chasemobile to watch the line approach. I live streamed a view of the cell to my south:

NC cell

Other than a close CG strike nothing exciting happened here. It was a very pleasant and quiet intercept as the line did a split around me.

When the southern cell reached my longitude I pulled up stakes and headed back west to check on the anticipated later convection. Diverting to the North Carolina welcome center on Rte 29 I tried to visually examine some cells south of there but was thwarted by trees and topography in that area. Noticing more convection to the north (visually and on radar) I jumped back on Rte 29 and sped in that direction.

After dithering a bit on where to intercept the developing line segment I finally stopped at a spot north of Chatham. My position just off Rte 29 afforded open vistas to the west and northwest. The “Tail-end Charlie” cell to my west was heading right at me, albeit slowly, and I switched on the live stream. The next cell north of it actually exhibited a brief lowering at the time of this storm relative velocity radar view:

IMG_2365However the better action was on the end cell. I watched it for quite a while and saw a wall cloud coalesce and persist. Although the parent cell showed some broad rotation the wall cloud itself showed no obvious rotation:

Wallcloud NW of ChathamThis view is from a few minutes later as the lowering came directly toward me:

Second view of Chatham wallcloud

After the local TV station used the live stream at the end of its 5:00 news and the beginning of the 6 o’clock broadcast I headed west. The plan was to stop in Rocky Mount for dinner but I was delayed by yet another interesting cell. I stopped and started along Rte 40 a couple of times before pushing north on a county road to snap this photo of a hail shaft on the backside of the storm now east of me:

Hail shaft on Union Hall storm

I moved a half-mile further north and the storm structure showed inflow and faint striations:

Incipient rotation on Union Hall cell

This photo corresponds to the following radar velocity depiction:

IMG_2388

As this action continued south and east I finally threw in the towel and headed for Rocky Mount and a late dinner.

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