The replyies above are all good answer. But resorts will have thier internal poliecy regarding windhold.
Winds blowing striaght down the line, aren't as bad as blowing directly across the line. cept for gondolas
Resorts hate to go on windhold,,, but in the name of safty they do it.
Fixed grip triple chairs weigh n the range of 300-500 lbs, detachable chairs anywhere from 1,000 to 1,500 lbs
Gondola cabins? not sure, but if any type of lift goes on windhold, first to go is the dola in most cases unless it was built in a well protected area.
Where i was employed for 15 years, our policy was if winds were over a certain speed, the Lift Maint. dept would turn the speed of the lift down. And if they still kept getting auto shut downs, and they have done every trick in the book, they would call the bottom for last chair , and put it on wind hold. Lift Maint. had that right since it was thier responsablity to esure the lifts were running safely. (they keeep in contact with Patrol for the most upto date weather, also with other resorts in the area) 3o mph was the max speed of the wind to operate a lift safely. Any higher, it's onhold.
Each lift tower on both side have safty switches. If the haul rope(cable) or the grip comes into contact with thses switches( brittle bars, thin pieces of metal or plastic) it will shut the lift down. Lift Maint then determins which tower went "out". They can either bypass the switch, and go for restart, to get every one off, and another 'tower monkey' will ski down to the tower with the bad switch and swap it out.
When the winds are going right across the line, this can cause the rope to move side to side, thus breaking the brittel bar ,this will cause the lift to shut down, another built safty. Tower monkeys will take tools with them, to the problem towers, and sit ontop (you may of seen a guy siiting on a tower) of the tower making adjustments to the sheave assemblies( the wheels you see on each tower) They can only adjust it so much, then they will put the lift on wind hold.