I'm about 90% sure it's going to be the Adirondack Thunder. Searching Trademarks and all that, the only Adirondack trademark registered lately by the Calgary Flames is the Thunder. And it looks like it was updated on Jan 27, 2015 (a couple weeks after initial reports of it being registered) and then updated again on Feb 2nd.
https://trademarks.justia.com/865/10...-86510174.html
http://tsdr.uspto.gov/#caseNumber=86...e=statusSearch
I can't seem to find the logo that's trademarked under this though. It's still listed as a "wordmark with no specific colour or font".