Rob has a good writeup of what to expect over the next few days (no point in regurgitating the same info) and has a few interesting stats about this immense low pressure system.  I will just reiterate that all through the RRV, we will see very strong winds pick up tonight, with potential wind gusts in excess of 90 km/h, so bring things in that could flap around.

The NWS has confirmed this low, currently sitting at 956mb as the strongest low pressure system on record in the Northern Plains.