Well Here is how it played out,
Travelling through the Nordheim region my (not dressed for the weather) group of escapees had just made their hourly fortitude save for cold and came to a bridge that crossed a 30 section of sheer drop to a mixture of water and sheets of ice 25 feet below. This was the first of two crosses they would encounter. The DC on this was pretty easy Balance check of 15 if they lost their balance I gave them a DC10 to have them slip and their armpit basically ram into the rope holding them up. No one did worse than tha. Oh yeah it was only 2 foot wide. I thought about incorporating wind but did not.
Then I came to the entry to a cave with an old wooden door under about 5 ft of ceiling from the outside of the mountain. When they opened the door with force rather than picking the lock. It created an avalanche that caused the slide to bury a few ,thankfully in towards the door,(That hurt a bit, but was very unexpected by the group). They then had only one way to go, so pressed on, meeting a new adventurer to our campaign and after freeing him they came across an ice bridge.
The ice bridge was great, 3 feet wide no holding on and a 25 ft chasm. Some thought of jumping and oh how I hoped they would try(It would of been Ballsy) However they did not. The first 2 made it across safely DC 15 at half speed so 2 rolls were required, 30at normal movement. However the next player slipped and then needed a DC 10 to kind o lay their and not slide with another DC 10 to get up. ( easy Right?) Wrong. He started slipping off now this was a 50' drop to doom. So I had him role a DC 5 to quickly pull a light weapon and ram it into the ice to hang on. No problem right? Wrong He fumbled. I had another player DC 10 roll to dive and grab him then a DC 20 to get him up to his chest. The other player(the one hanging then rolled DC 15 to get himself up, I was feeling generous)

Now This was just very funny because they had all made it eventually minus one and he fell, then was sliding off and then couldn't roll to get up. So the person that came out to help him up kept falling and they ended up helping each other at times. It was very funny!! The players loved it. I started out awarding +2 to rolls for assists ,but if the player layed out and dug in and grabbed for a hanging player I gave a +4.
It worked out well and taught them that enemies are not the only encounters they will face, atleast that is the way I like it.
So please let me know if you try something similar and how it plays out
Tom