Microburst
Looks like windshear from a microburst, recent weather conditions are conducive to such an occurrence. Microbursts last for avg 5 minutes and can affect an area up to 5km wide, they materialise due to downdrafts from Cu/Cb clouds. I would guess the a/c entered the most dangerous tailwind portion on short finals. Given eyewitness reports sounds like pilot flying did the right thing holding her at CLmax and the resultant relatively low airspeed accounts for very short landing roll.