Alps

The Alps (German: Alpen) is a mountain range in Central Europe, spanning through Austria, France, Germany, Italy, Liechtenstein, Slovenia and Switzerland.

Teenage Mutant Ninja Turtles appearances
In the 1987 cartoon episode  A Real Snow Job, the Ninja Turtles, Splinter, April O'Neil and Irma visit the Alps in Austria. Splinter reminds how the mountains remind of his native Japan.

It's in the middle of winter, when Krang starts melting the glaciers Earth. This causes the snow in the Alps to melt.