Scud or?

[Kurt Silvey]

I installed Adobe Premiere Elements last night and was playing around with some video my son filmed last year in SW Iowa. So anyway, I thought I would see what others thought about this clip. Is it scud or a legitimate wall cloud and funnel? At about 35s into the clip the cloud develops a well-defined funnel, but then begins to fizzle away. In real time the whole event took about 10 min.

As for the program, I really like it I installed it and went right to work without reading anything. Very simple and appears to be able to do everything I want to do, and at less than $100 you can't beat it.

http://www.pdswatch.com/kurt/Coin%20IA%20Scud.wmv

 

[John Diel]

Starts out as scud. Could be something more towards the end of the clip, but since I couldn't see a storm based feature (Meso, Rotation, etc.) I can't say for sure.

That means I'd call it vigorous scud

 

[Robert Dewey]

I would have to say scud as well... The "wall cloud" feature didn't develop from the top down, rather it condensed upwards. And, I didn't see any rotation. Still pretty cool video with that very low condensation level and vertical motion.

 

[Tony Laubach]

Yeah.. definately looks scuddish... would be worth looking at what was going on above it..

 

[Karen Politte]

Scud. Forming likely from rain-cooled downdraft, condensing, appearing, and being drawn into the updraft base of a non-tornadic storm.

 

[Verne Carlson]

Hard to detect any rotation in the updraft so most likely Scud. I bet alot of people would call it in as a tornado though.

 

[Kurt Silvey]

Actually the storm was Tor warned. This was filmed about 10 min after, and just a few miles east, of the Coin, IA tornado last August. The main meso was just to our northeast. I believed this to be scud also, but then it attached it’s self to the cloud base and did develop some rotation. But as pointed out it did develop “upwardsâ€￾ and not down from the cloud base.

 

[Andrew Geil]

Tornado!!!


(Sorry, someone had to say it).

Looks scuddish to me too.

 

[Doug Lee]

Scudnado? :roll:

 

[David Drummond]

I've seen plenty of VERY NICE wall clouds that even eventually went on to produce tornadoes that started out as nothing more than rising scud.

I get the impression that this was a wall cloud wanna be that couldn't quite get it's act all the way together. I can't see any other features, but given the NWS had a warning on it they obviously saw some signs of tornadic potential that gave them concern, which tell me the storm probably had wall cloud forming potential.

A wall cloud is essentially the visual representation of the cooler, moist air being ingested back into the updraft. Cooler air, condenses fastest (aka lower).... tada wall cloud.

 

[David Drummond]

Scud. Forming likely from rain-cooled downdraft, condensing, appearing, and being drawn into the updraft base of a non-tornadic storm.

Which is what a wall cloud does. Storm doesn't have to be tornadic to form a wall cloud, in fact, most storms with wall clouds are never tornadic, but you knew that. :wink:

 

[Jeff Miller]

agreed

I have to agree with David here.

There have been countless time lapse photography of wall clouds forming as scud rapidly rising into the rain free base as the main updraft intensifies and pulls in rain cooled air which condenses at a lower level due to it's saturation. Wall clouds do NOT have to rotate to be considered a wall cloud, simply attached to the rain free base in the updraft portion of the storm.

In the case of the video presented here, it is scud with transitioned into a ragged non-rotating wall cloud structure. Scud is fragmented and not attached to the cloud base where a wall cloud IS attached to the UPDRAFT base, rotating or not rotating.

There are cases of scuddish features attached to a clud base in NON updraft areas of the storm, but because that is not in association with rapid vertical motions in relation to updraft with rain free base, it is not a wall cloud, simply a lookalike.

Kurt mentions that the storm was tor-warned for rotation. To clarify, did not note rotational tendancies with this feature, that does not make it any less of a wall cloud in the latter frames. Again, definately scud at the beginning.

 

[Mike Peregrine]

Throwing my vote in with David on this one as well ... a couple of considerations, though ... being that we are unable to see the entire structure here, it is really a tough call ... being there in person, we would be able to judge the relationship of this feature against other structures, RFD, inflow, etc. Condensation of rain-cooled air upward into an updraft base is exactly how wall clouds form ... and anyone who saw the initial formation of the Hallam storm last year can testify how rapidly a wall cloud can develop and almost simultaneously drop a tornado.

My conclusion here: inconclusive. Our judgment in this case is unable to be conclusive because there is not enough information. The upward motion is pretty suspicious to me, and can easily start indicating rotation. As I recall, the Coin cell experienced a split shortly after or around the time it produced the tornado near Coin (would have to go back and look at radar to be sure) ... but it is at least possible that you are located on a separate cell from the original mother cell here as it was making its split and briefly spinning away (I say briefly because it quickly lost signs of rotation on radar as it made a split to the north).

I've watched lots and lots of bona fide wall clouds start out as nothing more than wimpy scud that spun itself up, attached to the base and then started rotating like crazy.