As, during the day, the temperatures have been getting into very low pluses, some of the snow that fell melted and then froze again before it dispersed.
That is a snow clearence problem, to not get the snow out of the way in the first place. Secondly a de-icer problem, for not laying down enough precautionary agent in advance to prevent it from sticking.
And FYI: When itīs too cold for Aviform/Safeway/Urea: Sand!
Shock-horror- etc etc Sand at an airport? Well yes, and itīs no major problem/disaster!
There are even gritters that can coat the sand with water steam as it exits the hopper onto the disperser rotors, making the sand freeze to the surface on contact. Lasts for days.