yeah.. I'd say you are in trouble there.
Police will probably close the road at Maydena.
What sort of vehicle are you driving?
If you can get your hands on snow chains they are a good insurance policy and may get you through in a 4WD.
1mm of rain = 1cm of snow. It's really hard to judge depending on the freezing level and whether the forecast plays out.
15cm tomorrow and 20cm Saturday - it's going to be very hard to keep the road open.
But it's been changing around all week.
Keep an eye on:
https://www.police.tas.gov.au/community-alerts/