There's many a snowstorm at Epsom! (5)

I believe the answer is:
downs
'there's many a snowstorm at epsom' is the definition.
I can't tell whether this defines the answer.
'there's many a snowstorm at' is the wordplay.
'there's' is a charade indicator (letters next to each other).
'many' becomes 'D' (Roman numeral for 500).
'a snowstorm at' becomes 'owns' (I can't justify this - if you can you should give a lot more credence to this answer).
'd' put next to 'owns' is 'DOWNS'.
Can you help me to learn more?
(Other definitions for downs that I've seen before include "Gently rolling hills" , "S. England chalk hills" , "Naturally part of SE England" , "North or South, two features of chalk upland in England" , "Drinks in one" .)
