Most examples from newspapers imply that a blizzard of horseradish is a torrent of unhelpful or irrelevant political verbiage:You learn something every day. Now I have a new euphemism to use.
Horseradish is on record from the 1920s meaning arrant nonsense or rubbish, a relative of horsefeathers. Both terms are euphemisms for horseshit or bullshit. It’s possible that an unbowdlerised alliterative form blizzard of bullshit could already have been in use around that date; it’s recorded only within the past decade, but that doesn’t mean a lot as it would have been considered too rude to print much before then...All the righteous indignation which drifts down Capitol Hill like a blizzard of horseradish is simply partisan politics.The News and Tribune (Jefferson City, Missouri), 3 Feb, 1974.
A few sources suggest where it comes from:
The death of Ho Chi Minh has left policy-makers at the State Department, and the men who convey their thinking to the public, lost in what Groucho Marx once called “a blizzard of horseradish.”Naugatuck Daily News (Connecticut), 10 Sep. 1969.
23 August 2013
"A blizzard of horseradish" explained
I had not heard this phrase before, but I had heard of "horsefeathers." They are related, as noted at World Wide Words: