I'll summarize my thoughts from the Discord:
I don't think this is an attempt at a new OTA weather channel or anything close to WeatherPlus. I think this is a vehicle to enable the hubbing of weather. The press release says "Fox Weather will feature local, regional and national updates... [Drawing] on more than 75 meteorologists across 17 stations and Fox News Channel’s news gathering teams." and makes no mention of affiliate stations. This is a project that involves only the O&O group.
Rebrand all the local weather departments under the "Fox Weather" banner (Which would be similar to WeatherPlus) and now you have a unified brand that anyone can appear in front of. Do you really need weekend meteorologists at both WITI and WFLD? Or can you just "regionalize" these markets and do both out of one station from time to time? Oh no! A Tornado warning has been issued on a Sunday morning, and nobody's at the station! Not to worry, the Mothership in NYC has somebody on duty, and they were going to cover the Tornado warning anyways, so they might as well just simulcast Fox Weather on the local FOX O&O.
I would not be the least bit surprised if midway through next year, they announce they're "streamlining" the O&O's and are taking advantage of "operational efficiencies" presented with a network of meteorologists and suddenly some stations lose their weekend/fill in mets. I've said for some time now that Weather and Sports were ripe for hubbing, and I think this might be the start of that.