Frost Wave

Across the Frost Ridge Heights during deep winter a flash Gleacer forms called the frost wave. The wave can stretch across the region from the fjords of Cyrah and the Gheshoo Mountains, even affecting the city of Blastingburg during particularly cold years. A few frost waves develop throughout the season.  These flash glaciers only occur during the nighttime. The affected area will see the landscape turn from winter fields and valleys to a block of ice overnight.
When a frost wave occurs ice forms on every surface in the defected area.  The ice grows and expands several inches a minute. Any living creature caught exposed to a frost wave can be encased in ice. The frozen creatures are kept in stasis until the ice melts. The ice will often melt in a few weeks or with the coming spring however in some rare cases or conditions parts of the frostwave can remain frozen for sentery preserving the life inside. The ice itself tends to be soft and wet making it easy to dig through however when tunneling through collapse is comen. The ice can build up to fifteen to thirty feet swallowing entire settlement.
Settlements defective by Frost Waves often keep large stockpiles of fuel and extremely tall chimneys sometimes reaching twenty to thirty feet tall. the settlements' feathers to the west will keep central fornices for the village with heating pipes leading to many of the homes and shelters of the settlement. Ritcher towns will even invest in magical heat sources to prevent the recurring cost of fuel. A few of the largest towns will even dig an undercity so the main street districts do not have to shut down during a frost wave and prevent the usual disruptions that occur.
The causes of frost waves are unknown however the universities are researching the phenomon.