'Lines' That Form Near Storms

James K

EF2
Mar 26, 2019
171
70
6
Colorado
See attached image.
The lineup of small storms you see was moving southeast-ish,
But note south of them, there's a 'line' (2 actually) that was moving faster than the storms....

I see these show up on occasion (not always in front of storms, and usually only a single). Is my assumption correct, that that is simply an outflow boundary?
 

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Dan Robinson

Staff member
Jan 14, 2011
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St. Louis
stormhighway.com
Yes, those are outflows from earlier storms. If you look at a longer loop, you'll probably see the bigger storm complex upstream that created it. Sometimes these are a stationary frontal boundaries that get a push from storms that form on the cold side of them. In either case, the boundary acts like a cold front once it is on the move (it essentially is one, technically speaking), which can trigger new storms along and behind it, which keeps it moving.
 
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James K

EF2
Mar 26, 2019
171
70
6
Colorado
Thanks Dan. Confirmed what I thought :)

In this case those storms might have been what created it...they were in the dieing-out state when I captured the screenshot.


I did once see a couple new storms fire off one of those boundaries (they grew fast too)...but that was also a day that had more moisture & higher CAPE to work with.