Richmond VA outflow

[Jody Radzik]

Hello all.

As I was watching the thunderstorm line on radar that passed through Richmond, VA on Friday night, I noticed an intense set of reflections that formed in front on the line in a very short period of time:

http://atman.net/nmupdraft/richmond1.jpg

http://atman.net/nmupdraft/richmond2.jpg

I'm assuming this is outflow-initiated convection, but the speed with which these storms went up seems incredible. Five minutes elapsed between these scans. I was hoping to have my notions confirmed or corrected per a more experienced analysis.

Thanks all for the help.

--jody.

 

[Dan Robinson]

That's a radar artifact - not sure exactly what causes that, but I've seen it many times. Could be ground clutter or possibly something similar to the 'sunset spike'. The same thing is happening at KLOT right now.

 

[mikedeason]

Looks like AP to me.

 

[MClarkson]

Ya, the lowest tilt beam is starting to hit the ground...

 

[Jody Radzik]

So, is this an atmospheric effect that bends the beam toward the ground in front of the approaching storms?

 

[MClarkson]

Yes, there are a number of atmospheric components that can cause the beam to bend differently than it normally does. The most common is a temperature inversion... the cold gust front from the approaching storms was likely the culprit here in causing the beam to bend a bit too much and start impacting the surface. Basically a good rule of thumb is that if its near the radar site and doesnt look quite like a thunderstorm should, you should begin to suspect ground clutter.

 

[ELY M.]

yesterday, I was looking at radars and I saw interesting line near twin cities. storm chaser in that area told me that they are mammatus clouds.
I know lines can be anything.

 

[MClarkson]

Weather radar does not detect clouds.

 

[Jason Persoff]

Hey Jody--there are some other features on the radar image which ARE outflow-related. The line of storms clearly has a front spreading gust front immediately parallel and a couple of miles ahead of line. Though the dbz of the 2nd image becomes cluttered by ground clutter, at least you have a good image of an outflow-dominant line. Take a look again.

The other comments above are correct, but I'd add that another big tip off is the radial nature of the radar signatures. You'll see spokes spreading outward from the radar site which are not features of storms in general. That can sometimes help distinguish these.