Trail update:
I just went onto Winnisquam from my house (midpoint of lake) and rode a big circle. I went up the lake and crossed over to Paugus Bay using the Prison Loop and SouthDown Shores Trails... I then followed the tracks down through town and back onto Winnisquam near where the Winni River dumps in... then obviously back up the lake to my house.
If at all possible, do not ride the tracks! The rails are exposed and in places where multiple sets of tracks come together it was very hard to keep my skis from catching the rails. You'll be doing only three to five miles per hour if you choose to ride this section of track right now. You'll also have to cross paved road/traffic in about ten spots. It would be much quicker/safer to ride north on Winnisquam and cut across on the mid lake trails, crossing paved roads only twice.
However... there are quite a few spots on Winnisquam with water/slush above the ice and below the snow. If you don't have a picked track, you'll want to keep moving. Stop and you'll probably spin down to bare ice.
Another caution... the snowdrifts that formed on the lake prior to the last snow are still there. They are hidden. It looks smooth, but in reality you will hit some hard drifts that want to launch your machine! Its not too bad, but beware... especially if you are towing a sled.
Ride safe and catch lots of fish!!