The Sunspot Observatory sits atop a mountain overlooking Holliman AFB and White Sands Testing Grounds.

White Sands has been used in the past as an alternate landing site for shuttle missions. Perhaps it is being utilized for this yet again. Either the TR3B or another craft from the secret space program is making an unscheduled landing. Florence could be impacting landing sites on the East Coast, like Andrews AFB, forcing them to utilize White Sands. Shutting down the observatory prevents prying eyes from seeing something they're not supposed to.