What happened

Shares of specialty-clothing and accessory retailer Zumiez (ZUMZ 6.49%) jumped as much as 19.2% on Thursday. As of 1:19 p.m. EST, the stock is up 13.9%.

The stock's rise reflects better-than-expected December sales, and management's decision to raise its guidance for fourth-quarter comparable-sales growth and earnings per share.

A person in athletic shoes riding a longboard

Image source: Getty Images.

So what

Zumiez December net sales increased 11.4% year over year to $160 million. Comparable sales, or sales at stores opened more than a year, increased 7.9% year over year. This marks a slight acceleration compared to November comp-sales growth of 7.8%, and it's a huge increase compared to the 3.4% growth Zumiez saw in December last year.

Citing "stronger than expected quarter-to-date sales and product margin performance," Zumiez now expects fourth-quarter comparable sales growth of 7%, up from a previous forecast for comp-sales growth between 3% and 5%.

Similarly, Zumiez said it now expects EPS to be between $0.88 and $0.90, up from previous guidance for between $0.78 and $0.84.

Now what

The company's ability to achieve strong comparable sales growth on top of positive comps in the year-ago quarter has been impressive. But Zumiez investors will want to keep an eye on sales comps to see how long this notable growth level can be sustained.