Ms. Upp left New York in 2010 and worked at a Quaker study and retreat center outside of Philadelphia, according to a newsletter written by her father. She then became a teaching assistant in Montessori schools, including one in Maryland. There, in September 2013, Ms. Upp experienced another dissociative fugue episode, this time disappearing for two days.

She moved to St. Thomas the next year for a new job teaching 3- to 6-year-olds at the Virgin Islands Montessori School.

“Whenever we do a tour for a new family, the first classroom we visit is Hannah Upp’s,” said Michael Bornn, the head of the school. “She’s one heck of an example; she’s not just a Montessori teacher, she’s a passionate Montessori teacher.”

While Ms. Upp may be suffering another dissociative fugue episode, it is far from a foregone conclusion. She could be caught up in the chaos following the two storms. Members of her family, who declined to be interviewed, instead released a statement emphasizing the unknown nature of her present condition:

“Our beloved Hannah has disappeared. We do not know what has happened and we are hopeful that she will be found alive and well. Our thoughts and prayers are with Hannah and all those who continue to search tirelessly for her. We know our fear and uncertainty is shared by many others, and our hearts go out to all who wait.”

With much of St. Thomas and the surrounding region heavily damaged and many people still missing throughout the Caribbean, Ms. Upp’s disappearance “couldn’t have happened at a more difficult time,” Mr. Bornn said. Federal searchers and the Coast Guard are preoccupied with hurricane recoveries, he added, and Ms. Upp may not be “on the top of their radar.”

Some of Ms. Upp’s friends and colleagues have taken matters into their own hands: Jake Bradley, an emergency medical technician who has helped to lead the search for Ms. Upp, told The Virgin Islands Daily News that “we’ve done all the physical searching that I think we can do, other than having her posters put up everywhere.” The hope, he added, is that even if Ms. Upp is in a fugue state, she will see a poster and recognize that something is wrong.

Mr. Bornn, who has been in frequent communication with Ms. Upp’s family while trying to raise money to keep his school’s doors open, stressed that even in a fugue state, Ms. Upp would still be fully functional — just not as herself.