This is an update on the information that I sent to you the other day:

Wikimedia Technical Operations department is planning an important test of the new "full" data center in Texas.  The test will result in about 30 minutes of downtime for all the wikis, including Commons, Meta, Outreach, all Wikipedias, etc. on two days that week.  You will be able to read but not edit. 

This work was originally scheduled for this coming week, but has been postponed until the week of 18–23 April 2016.  

Official schedule:  https://wikitech.wikimedia.org/wiki/Switch_Datacenter#Schedule_for_Q3_FY2015-2016_rollout

Background information:  https://meta.wikimedia.org/wiki/Tech/Server_switch_2016

Note that these two pages have slightly different dates; I'm trying to figure out which is the correct set of dates.  If you are scheduling training events or edit-a-thons during that week, then you may want to contact me to get updated information soon.

Also, if you experienced problems with the five-minute read-only test on Tuesday, 15 March around 07:05 UTC, or if you have suggestions for places to announce this, then please contact me in e-mail offlist or on wiki at http://en.wikipedia.org/wiki/User_talk:Whatamidoing_(WMF)

Thanks,