Many thanks to SWLing Post contributor, John Johnson, who writes:
Well, based on this post from Carlos Latuff–QSL: Australian Radiofax Received in Brazil–I got interested in HF weather fax decoding. I asked how to do it and got an answer but did not find a linked post that would help.
So as usual a wikipedia is helpful: WEFAX – Signal Identification Wiki
Which led me to realize… I already owned the Black Cat Systems decoder in my iPhone, but alas had never tried to use it!
So I reinstalled the HF FAX program. It had been included in a package of iPhone ham software programs I had previously purchased. I then searched the frequencies linked here: Marine Weather Broadcasts from the USCG
And soon after on 12179kc on my D-808 around Noon eastern time on 11/4/23 was decoding my first partial wx fax from Boston, I believe:

I then started fine tuning the D-808 and as you can see the fax quality began to improve significantly…

Alas the signal ended very abruptly, before I could perfectly tune it… I never received a complete fax but this was a fun radio exercise and I will keep at it.
WxFax (this is my name for it) reminds me of my NDB beacons. Both are older tech that appear to be rapidly disappearing. Just last night I was happy to tune two new but weak Canadian LW beacons from my Michigan location on my D-808. Alas I then refreshed the dxcentre NDB list–at: https://www.dxinfocentre.com/ndb.htm–only to find that I would be losing 3 relatively strong beacons to decommission within weeks! Such is the life of an LW NDB chaser in the year 2023.
Thanks to Carlos for giving me something else to chase on SW HF!
John Johnson (N8ELK)
This is brilliant, John! The more you work with the app and reception, the better you’ll get at clear decodes. It’s a skill you’ll build very quickly. Thank you for sharing this!