Uncle intel, 18 Space Control Squadron is predicting a nearly thirty percent chance of collision between two large non maneuverable satellites at 14:02 universal time tomorrow at an altitude of about 615 km.

Not certain which satellites are posing the collision risk but I'll update when I know more.

*Update: I'm hearing the satellites involved are Cosmos 1461 and Kanopus V3. Both are Russian satellites. The former was a naval reconnaissance satellite, the later was a high resolution earth observation satellite.

You can follow the orbits of the two satellites here:
[link to www.n2yo.com (secure)]
[link to www.n2yo.com (secure)]

Or here, but you'll have to manually refresh:
[link to www.heavens-above.com (secure)]
[link to www.heavens-above.com (secure)]

*Update:
Doom off!
"(17 Sep 1430z) The close approach predicted at 1402z on 17 Sep 2018 has passed without incident. 18 SPCS/CSpOC has confirmed that the primary satellite is being tracked as a single object, indicating that no collision has occurred."
[link to www.space-track.org (secure)]