Heavy snowfall blasts the countryside reducing visibility to just a few feet. Travel through the area is even harder than usual as slips, trips, and falls are difficult to see.
High Winds. Ranged attacks are made with disadvantage , unattended and poorly secured objects fly off in the wind, and flying is nearly impossible (requiring an Acrobatics check each minute to avoid plummeting to the ground).
Intense Cold. At the end of every hour spent traveling through this area, a creature makes a Constitution saving throw (DC 5 + 2 per previous save) or it takes 3 (1d6) cold damage.
Reduced Visibility. The maximum range of any sight-based senses is 10 feet. In addition, Perception checks are made with disadvantage , and all passive scores (including passive Perception) are reduced by 5.
A group Survival check allows the party to find or construct shelter and outlast the storm. Alternatively an Athletics check (or Animal Handling if mounted) can be used to outrun the storm.
Critical Failure: The party loses 5 (2d4) hours of travel time facing the storm head on. In addition, each adventurer loses 2 (1d4) Supply that’s dropped or ripped away by the wind then quickly covered in sweeping layers of snow.
Failure: The adventurers lose a day of travel as they get lost due to covered landmarks, disorientation from the storm, and the need to move more slowly at times to avoid danger.
Success: The adventurers either find a small alcove and can wait out the storm in relative comfort, losing 5 (2d4) hours, or successfully outrun it losing no time.
Critical Success: The winds shift and the worst of the storm passes the adventurers by.