I'm sure most folks know this but just in case.
Besides moving faster than a person( at least some of us) a person with a pack exerts more weight per sq inch on the ice than a snowmobile does, so snowmobile tracks across a frozen lake might not mean it's safe for us.
Once it gets cold and there is a substantial ice thickness, in and outflowing water moving under the ice can thin the ice substantially. If crossing a body of water you are unfamiliar with, try to avoid areas where water is moving under the ice.
Objects like tree trunks protruding from the ice or from shore that are frozen in the ice's surface can weaken the nearby ice. The tree bark absorbs more heat than the reflective snowy surface and the ice may not be as thick nearby. Late in the winter season, the sun gets higher and warmer. The sun melts the snow on the shore and the soil absorbs heat, warming and eventually melting the ice nearby. I've crossed onto frozen lakes at 5am on a warm late Feb day only to find open water sometime requiring a running broad jump to get back to shore late in the afternoon.
Anytime I cross frozen water, I unbuckle my pack and sternum straps and loosen the shoulder straps. You don't want to be under the ice trying to surface or get out with a pack pulling you down.
I know this didn't answer the OP, but thought I'd throw it out there.
Usually, once there is a heavy sheet of ice on a lake, a day or even a few days of rain usually does nothing but pool and then freeze on top of the existing ice. Unsettling to walk on as you can keep falling thru the top skim of recently frozen rain.