I would pronounce
Alana as "uh-LAH-nuh."
Just for comparison sake, I'll add that I would pronounce
Elena as "uh-LAY-nuh" (or close enough) and
Alannah as "uh-LAN-uh."
I prefer
Elena and
Alannah to
Alana, sorry.
Have you ever heard of Alani? It's a Hawaiian girl's name meaning orange tree. It is pronounced, "uh-LAH-nee."