We already know, as there are manual snow course surveys and snow pillows all over the place. Here is a list of 400 or so (some are historic and no longer sampled) snow courses in BC. Many of those get visited every two or four weeks from Jan-Feb through June each year.
I've done the surveys, and you need to measure both snow depth, and moisture content. The process of manual measurement hasn't changed in decades - you drop a metal tube into the ground, pull it up, dig out the soil, measure the weight of the snow that the tube collected, and the depth of the snow. Of the two numbers, the overall moisture content is of greater interest. I hardly even look at snow depth when trying to decide if the water systems I run are facing a drought - the moisture content compared to historic trends is what matters most.
Even then, snow depth is only a guide. If you get high evaporation rates during spring freshet, or lots of wind and moisture loss, what appears to be a healthy snowpack in April can turn into near-record low runoff by June. This year that is exactly what happened in my region. We had a good snowpack, with normal amounts of water equivalent in April, but by June, very little runoff to the reservoirs had taken place. This mostly affected the low and mid elevation watersheds in the Okanagan. The really high elevation watersheds such as Mission Creek had normal runoff, while adjacent watersheds such as Mill and Hydraulic Creeks ended up with varying levels of drought.
More data is always a good thing, but the moisture content matters more than the depth. And even if the data looks promising, that can change in a matter of weeks. You never really know for sure how much water you're going to get until the reservoirs stop filling.