Storm shelters can be referred to as mountain shelters, bothy bags or group shelters, but essentially it is the same piece of equipment.
Although they may seem cumbersome at first, and the appearance of another group using them may even seem humorous as they flap about high on a hill, they have a place which should be considered by your expedition groups.
Imagine them as hungry. It is lunchtime and they really should stop and replenish the fuel for the energy systems, but it is cold and wet, and to do so could make them even colder. These are the circumstances in which a storm shelter can be the answer. Combined with a mat to sit on, and a spot slightly out of the wind, almost immediate relief can be found from the conditions. The more bodies inside the shelter then the quicker everyone will warm up, and there will be enough time to take on the much needed calories.
Storm shelters come in a few sizes, from one or two capacity, up to eight to ten. Having one or more shelters sufficient in capacity to house everyone in the group would be sound advice.
A storm shelter could also be a life saver in an emergency situation. If you or one of the group could not walk, the first priority is to remove the casualty from the harsh external environment, especially if it is raining heavily or windy. That way the casualty will be protected from getting any wetter, and cooling by convection will stop immediately, thus stopping or slowing the onset of hypothermia. Perhaps first aid needs to be administered or the group needs to call for and wait for help to arrive, but it is clear that keeping as dry as possible is key to preventing heat loss. Having company for the casualty, as opposed to being stuck into a single person survival bag, can also be great for morale as well as providing heat from everyone in the shelter.
Stopping for lunch in a storm shelter is actually not as silly an idea as it sounds . In fact, it has many safety elements attached to it. If the conditions are poor - wind & rain - the chances are that the group will not want to stop for lunch and would rather press on to get to the end of the walk; a risk for hypothermia. Another favourite of hypothermia is that your energy levels are depleted as not enough has been eaten. Thus, stopping in a storm shelter not only gives time to rest, but also the group can stay dry in the process and take on calories.