Here's something interesting

[jtmal0723]

I haven't seen a setup like this before... It's two low pressure systems connected by a surface trough.... this whole thing looks like a spider web, lol I don't exactly know how this happens but it's an interesting thing to see!

[beanboy89]

Here's a clearer version of the map from weather.com:

[phw115wvwx]

There can be multiple troughs extending from one low to another.  How many times have you seen a low joined to another low by a front?  That counts, too!

[jtmal0723]

There can be multiple troughs extending from one low to another.  How many times have you seen a low joined to another low by a front?  That counts, too!

I've seen one joint by a front before... I guess I'm asking, what is a "surface trough"?

[phw115wvwx]

It's just an area on the surface that has lower air pressure than the surrounding areas.  There's no distinguishable difference in air mass across this trough, so they just mark it as a surface trough.  They're still important features as the lower pressure allows for air to rise and create clouds and precipitation.