A Snowdean is a type od daffodil flower (see
http://www.aorangi.co.nz/SpringCatalogue/A-D/DaffodilSnowdean.htm)
From an internet search, it seems that its use as a first name was somewhat popular in the first two decades of the twentieth century.
"Swow" is ultimately derived (accoring to Oxford English Dictionary) from the Greek "nifa", meaning snowflake; "dean" may possibly imply "vale".
I hope this gives a smile to the Lady :)