The melt
Most of the country gets its water damage at random. The Twin Cities get a schedule: five months of snow lets go in about three weeks, onto ground that is still frozen a few feet down. The melt is the annual exam, every basement sits it, and the grading, the gutters and the sump system are the answers a house has already written.
Why the water cannot soak away
The frost under a Twin Cities lawn runs deep by March, and frozen soil is pavement as far as water is concerned. The first weeks of melt cannot soak downward, so they move sideways: along the surface, along the top of the frost, along whatever path the lot offers. The path most lots offer ends at a foundation, because that is where the snow was piled all winter: beside the driveway, off the front walk, against the garage side of the house.
This is why a basement can take water in spring from a lot that sheds perfectly well in summer. The summer lot and the March lot are two different drainage systems, and only one of them has been tested by the time the carpet is wet.
The three weeks that sort the houses
A slow melt is gentle: freeze at night, trickle by day, the ground keeping up as the frost retreats. The dangerous years are the fast ones: a warm week with rain on old snow, everything releasing at once. In those weeks the water table itself comes up, and water arrives not only along walls but up through floor cracks and the cove joint where slab meets footing, in houses that have never been wet before. Flat, low neighbourhoods take it broadly; hill suburbs funnel it to whoever holds the bottom lot.
The sump system is the margin. A pit and pump that keep pace turn the exam into a hum from the utility corner; a pump that quit over winter, or a discharge line still frozen shut, turns the same afternoon into an inch of water across a finished floor.
What to do while it is happening
Move what sits on the floor first (the boxes, the furniture with particle-board feet, the rug), because contact time is what ruins contents. Confirm the pump is running and the discharge is actually leaving the house. And photograph the water while it is there: where it entered, how far it reached. The cleanup conversation and the insurance conversation both start with where the water came from, and the evidence is easiest to collect while it is still on the floor.