Originally Posted by
ratagonia
"It's a precipitation layer, not a storm." (paraphraseish)
I think you are trying really, really hard to miss the obvious.
Did the storm (aka precipitation layer) just north of Hildale dissipate, and then another storm (aka precipitation layer) swoop suddenly in and suddenly appear BOOM 15 miles to the north, 25 minutes later.
I realize the data is jumpy, but the storm moved north onto Hildale, and then continued north onto Keyhole.
Not sure where you live, but down here in Zion, the weather usually comes from the South (ish), maybe South-SouthWest. Usually. Can come from other directions, but most of them, on the radar timelapse, come from the SSW.
I just don't see what you are seeing or maybe, i don't understand how you are not seeing what seems obvious...
Tom