A storm with heavy snow and strong winds. Often used interchangeably with 吹雪 (ふぶき), though 雪嵐 can emphasize the storm-like, violent aspect.
See also: 吹雪
The trains stopped due to last night's snowstorm.
In the mountains, you need to be careful of blizzards.
Compound of 雪 (ゆき, 'snow') and 嵐 (あらし, 'storm'). The reading is a straightforward combination of the kun'yomi of each kanji.