Horseshoe Vortices?

[Mike Kruze]

I have seen horseshoe vortices a handful of times on both chase days and fair weather days. Most recently, I saw one a couple of weeks ago on an otherwise beautiful day; the vortex was somewhat isolated from a patch of small Cu. So my questions are...

How do horseshoe vortices form?
and,
Does seeing one on a day with severe weather potential indicate anything useful about the atmosphere that day?

[JHadorn]

http://www.casa.gov.au/fsa/2003/sep/58-59.pdf -- Has a section talking about horseshoe vorticies (see section "Three Dimensional Wakes").

I'm sure someone else can find you better information. I found a lot of the information I found about horsehoe voriticies dealt with water (they cause scour on bridge foundations).