I would say that it is definitely Swedish especially the spelling (the letter Ö does not look like this in Norwegian)
Löw means leaf (spelling nowadays is Löv) and dahl means valley (spelling nowadays is dal)
Dahl is pronounced like it's spelled DAH-l. Löw on the other hand is much harder to explain since the sound of Ö does not exist in English. If you know french it is pronounced like the French EU- combination (ex. jeune)
I'm leaving the explanation of the Ö-pronounciation to someone else.
According to Statistics Sweden (very reliable) only 48 people have the name Löwdahl in Sweden.
__________________________________________________________
Favorites : Ellen and August
The sleep of reason brings forth monsters - F. Goya