From Times Dispatch article:

Outdoor sirens will sound, digital signs will light up and alerts will be sent to phones and computers when Virginia Commonwealth University conducts a test of its emergency communications and alerting systems.

The full test will be conducted Wednesday at noon. In addition to sirens, it will include text messages, mass emails, desktop alerts, and notifications through social media and VCU’s website.
…
In addition to the semester test, monthly checks of the siren system are conducted at noon on the first Wednesday of each month.