April 19, 2013 Tornado-warned Supercell in Southern Virginia

 

chase images and log by William T. Hark, M.D.

 


 

I had been expecting severe weather for several days as a cold front pushed eastward. There was decent southwesterly upper level winds from an approaching trough and increasing low level moisture through the Mid-Atlantic. Dewpoints would be in the mid 60's with sufficient shear and CAPE. Storms would form in line and shift eastward as darkness approached. Although tornadoes could form along the front, I was looking for more isolated storms ahead of the expected line of storms. These isolated storms would have the best tornadic potential and would be the easiest to chase. The SPC had the area in a Slight Risk with a 5% tornado risk. By early afternoon, I noticed some clearing in a north-south band across central Virginia. More importantly, there was an area of south to slightly southeasterly surface winds from Emporia to South Hill by the VA-NC border. The 13Z (8 AM) HRRR model initiation showed an isolated storm that would move over Brodnax Virginia by 5PM and would continue to shift northeast. Brodnax is by South Hill on the eastern border of Mecklenburg County. South Hill would be my target.

I had already arranged to leave work early in the afternoon. My target of South Hill was set and my equipment was ready. A tornado watch was issued for central Virginia at 2:30 PM. I was on my way out when a local news station called to do a quick interview about the high levels of pollen. Their reporter was nearby and could arrive soon. I couldn't pass up this opportunity. I waited and was able to complete the interview with a 45 minute departure delay. I headed south on I-95 through Richmond and then southwest on I-85. As expected, there was an approaching line of storms from the west. An isolated supercell had already formed in North Carolina and was moving northeast. It became tornado-warned. I did keep an eye on some development just to my west but the weak shower died. I continued southwest on I-85 toward South Hill. This is very poor chase territory due to trees. The storm was really looking good on radar as it crossed into Virginia southwest of South Hill with significant rotation. I turned west on the 58 bypass at 5:09 PM and could see the storm by 5:11 PM. I headed west for a while on 58 trying to get a good view before turning around and following the storm eastward. It was showing rotation on radar and I could see a ragged wall cloud. The wall cloud looked especially good at 5:19 PM which coincided with increasing shear on radar. Luckily, I could easily follow the storm with the road network. At the I-85 exit along the 58 bypass/Route 1, I could still see the ragged wall cloud to the north at 5:24 PM. I briefly got on I-85 before exiting on Route 1 and following the storm to the northeast. Visibility is a bit better when not on an interstate in this area. The isolated storm continued to show weak rotation and be tornado warned. I headed northeast on Route 1. At 5:32 PM, I had a brief view of a possible funnel from Route 1 near the eastern edge of Mecklenburg County. This was at the same time the storm showed one last increase in rotation. I was trying to get closer and didn't stop long enough to observe the amount of rotation. The image below is from a video capture. I followed the storm northeastward along Route 1. Luckily, the storm was almost moving parallel with the road. The storm gradually weakened. I cut over to I-295 near Petersburg. The storm was merging into the line of storms approaching from the west. I ended the chase in Mechanicsville, Virginia.

There was a tornado confirmed for Mecklenburg County southeast of Blanks. The tornado was formed from the storm I later followed. I arrived too late. The delay for the interview may have cost me the tornado and due to multiple other news stories, my interview was never used. Oh well. It was an enjoyable storm chase in Virginia. My target was confirmed, and I was able to track a tornado-warned supercell with wall cloud and possible funnel. This chase also allowed me to test my equipment for the 2013 chase season.


4:14 PM; RadarScope image
GPS position is blue circle

Approx. 5:00 PM
Baron WxWorx/Mobile ThreatNet image
GPS position is the center white circle

5:11 PM; Approaching storm on 58

5:17 PM

5:19 PM; wall cloud

5:24 PM; at intersection 58 bypass
and I-85

5:30 PM

5:32 PM; possible funnel vs scud feature

5:32 PM; radar image of storm and
GPS when funnel/scud feature is seen

5:42 PM

5:56 PM; storm is decreasing intensity
.


Archived Weather Data

Surface Obs 2:10 PM Visible Satellite 2:40 PM 500 mb winds at 8AM 13 Z (9 AM init.) HRRR reflectivity for 5PM

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All images Copyright 2013 William T. Hark