Was at Tranquility with Chris tweaking the reroute Sunday afternoon. Surprised that the tread was slimmy, even though we haven't had rain for 2 or 3 days. I saw ice on SBL Sunday morning. With the constant mid 20's every night, I'm thinking frost is starting to show in the tread, with the slow, low daytime warm up keeping the trail slimmy well into the afternoon.
Though the slime is only 5mm thick and no half pipe, these trail conditions shouldn't be ridden, imo. Tires are loaded up beyond the knobs and mud is deposited on the bike. I think it's time for seasonal frost warnings and reminders to say no to mud. To beat the frost slime, one needs to ride singletrack only when temps are below freezing, or late in the afternoon if the warmer temp has dried out the tread sufficiently.