Warm-up and Refreeze: Why Our Foothills Turn to Mashed Potatoes
Okay. This is the lesson where I connect the dots between checking the weather obsessively (last lesson) and timing beating distance (opinion I'll stand by till I die).
Here's the thing about our foothills specifically. We sit around 4,600 feet, we get bright sun even in January, and the snow up near the point of the mountain and along most of our foothill trails is not the deep, cold, stays-frozen-all-day snow you get further up the canyon or up at the resorts. Ours warms up. A lot. Then it refreezes at night. Then it warms up again. Over and over, all winter.
That cycle is why a trail that's firm and lovely at 8am can be a swampy disaster by 1pm.
What's actually happening
Overnight, temps drop, everything on the surface refreezes into a firm crust. That crust holds your weight nicely in the early morning. Snowshoes barely dent it. Feels great, feels efficient, you think you're a mountain man.
Then the sun comes up. South-facing slopes get hit first and hardest, because the sun's low angle in winter beams almost straight into them. That crust softens from the top down. First it gets slushy. Then, especially if there's been a few warm days in a row, it goes full mashed potato, wet and heavy and grabby, and every step you posthole a little deeper than the last.
North-facing slopes and shaded draws hold their crust longer, sometimes all day if it's cold enough. So the same trail can have completely different conditions on the sunny side versus the shaded side, sometimes fifty yards apart. I've walked from firm snow into slop and back into firm snow in the space of one switchback.
Why this matters for planning
This is the whole reason I check the weather three times a day and don't feel embarrassed about it. A forecast that says "32 degrees, sunny" doesn't tell you when the surface goes soft, and that's the number you actually need.
Rough rule I use: if it's been sunny and above freezing for more than a couple hours, assume south-facing snow is getting soft. If we've had a warm stretch, multiple days over freezing, assume the whole trail system is softer than it looks, even in shade, even early.
Practical stuff you can do at home before you ever leave the house:
- Check overnight low and morning temp trend, not just the daytime high. A night that stayed above freezing means less refreeze, means softer snow waiting for you at 8am instead of 10am.
- Look at which direction your trail faces. If you don't know, pull it up on a map app and just eyeball it. South and west-facing sections soften first.
- Plan your turnaround for before noon on anything with real sun exposure, especially anything after a warm spell.
- If you can only go in the afternoon, pick a shorter loop, ideally one with more shade, and mentally prepare for slop on the way back even if it was fine going out.
The trip where I learned this the annoying way
I want to be honest about this one because I did everything "right" and still got burned. Checked the weather three separate times before heading out. Saw a warm front moving in but figured, eh, it's just a few degrees, I'll be fine. Went anyway.
By the time I was heading back, the trail I'd walked in on packed and firm two hours earlier had turned into something closer to oatmeal. Every step sank six, eight inches. What should've been a forty minute walk back to the car took over an hour and I was soaked through by the time I got there. Nothing dangerous happened, just miserable and slow and completely avoidable.
That's where "timing beats distance" really comes from for me. It's not really about how far you go. It's about when.
The slow loop
I'll tell you about a morning that went the other way, because it wasn't about beating the warm-up at all, it was just a nice slow trip. Took Colton up in the kid backpack on a groomed foothill trail last February, early enough that everything was still firm. He fell asleep about fifteen minutes in, the way little kids do when they're bundled up and the walking is rhythmic. I didn't have anywhere to be, so I just kept doing a slow loop for close to an hour so I wouldn't wake him up. Same stretch of trail, over and over, snow crunching nice and solid under both of us.
That's probably the most peaceful I've felt all winter, any winter. And it only worked because I'd gone early enough that the snow held. If I'd started at noon that same loop would've turned to mush under my feet halfway through and Colton would've woken up to me swearing under my breath.
One more caution, plainly
Wet, refrozen snow can also get slick where it's crusted over, especially on any downhill stretch or where meltwater has run and refrozen into ice. Softening snow on top of an icy layer underneath is a good way to twist an ankle. Go slow on transitions, especially shaded downhill bits in the afternoon.
Before next time
Before your next trip, pull the forecast and actually note what time the temp crosses freezing, not just what the high will be. Plan your start around that number instead of around your own schedule, and see if the trail feels different than trips where you didn't bother.