Start with a good reliable soil test for soil pH and major nutrients.
How much organic matter is in that soil?
How well does that soil drain?
How well does that soil retain moisture?
What kind of critters, life, is in that soil?

You may still have time to spread some compost or a good organic plant food and getting the Soil Food Web active may well solve your thatch problem.

I agree with kimmsr about the applications of organic material that may accelerate decomposition of the thatch material even under the snow.

I might also add that thatch may well decrease throughout the next growing season once turf is managed to prevent so much root growth above the soil line.

Is water able to percolate through the thatch layer very well at all?