Improbability Wednesdays concern themselves with fiction. There are ideas buzzing ping-ping-ping against my skull and I let them out to annoy you, too. They're not even fully developed. But the key understanding here is that "improbability" means "not true".
Weirdness, on the other hand, I've decided to define as "good golly, gumby, I can't have read that right"; ie strange but true. I'll cast my net wide. Science, archaeology, politics, sociology. If I can't believe it, then I'll haul it up for you to chew on, too.
I am afraid Weirdness Fridays may evolve into ranting days. Outrage and weirdness do seem to go hand in hand.