We've had a few the past decade that began with a really cold start (near 0F) and that put the first 3-6hours straight in the DGZ since the "warm" tongue was relatively cold. Eventually we would end up pinging in the mid 10s anyway, but that's one way we squeezed out ratios from it. Of course the first few hours of 15-20:1 got a couple of inches of 9:1 sugar on top of it to pack it down in time for the 6hr measurement. By the time the sleet was done the initial fluff in the pack was a distant memory.