In my oppinion it is possible to respond even when there isn't any . According to this annotation:
i came to this conclusion:CRF, ruling by terms, Passive conditions wrote:Annotation 9: If a card specifies that an action is to occur as a result of some specific passive condition, this action becomes automatically the first action declared in the chain of effects to immediately follow the chain of effects producing the passive condition. The passive condition must exist when this resulting action is resolved in its own chain of effects, or the action is canceled. Note that actions in the strike sequence follow a different set of rules.
1- Snowstorm triggers when to company moves and checks for any (passive condition)
2a- With withered lands, snoestorm checks a and the company returs to site of origin (action resolved)
2b- Without withered lands snowstorm isn't able to check for a and the action is canceled (passive condition doesn't exist and action is cancelled)
Am i right? or won't Snowstorm trigger until there is a on the site path?