The server host will be making some updates and upgrades that will result in brief down times as they proceed. At this point, they are telling me the down time shouldn't exceed 15 minutes at a time.
There will be one more, hopefully last, downtime on Wednesday morning at 2am. This one might last up to an hour as they move everything to new servers.
There will be another update to the server in a few hours. The forums will be down for approximately 30 minutes in the time frame of 2am (Central US time)