Can I edit photos off an external hard drive when offline?

I edit on Lightroom CC on my iMac, storing originals on an external hard drive.  I would like to access and edit these photos on Lightroom CC on my laptop when I am travelling without internet, but if I plug in this external drive to Lr on my laptop without internet, the photos don't show up if they haven't already been synced to the cloud.  Is there a way to work off this external hard drive on my laptop so I can edit without internet?