why would sheltering in place under one of these desks be a poor choice in the event of a tornado?

Sheltering in place under a desk during a tornado is a poor choice because desks are generally flimsy and not designed to withstand the extreme forces of a tornado. Tornadoes can generate winds exceeding 200 miles per hour and hurl flying debris that can easily break or overturn a desk. This leaves a person vulnerable to injury from collapsing structures and high-speed projectiles. Additionally, desks are typically not anchored and provide little protection from structural collapse or larger debris. Safer options include going to an underground basement or storm cellar, or if those are unavailable, an interior room without windows, using heavy furniture and thick padding for added protection. Sheltering under a desk might create a false sense of security and prevent seeking safer shelter.