The number of people filing new applications for U.S. unemployment benefits rose last week to the highest level since September, but the underlying trend remained consistent with a firming labor market. The Labor Department reported Wednesday that jobless claims jumped 21,000 to 313,000 last week. It was the first time in three months that claims topped 300,000. The four-week moving average of jobless claims—considered a better measure of labor-market trends because it smoothes weekly fluctuations—rose 6,250 to 294,000, remaining below 300,000 for the 11th consecutive week, indicating that the job market is strengthening. This week's jump in jobless claims will not raise concerns about the broader health of the labor market, largely because some of the increase happened because of seasonal layoffs in businesses affected by cold weather, such as construction. Jobless claims have been below 300,000 for 10 consecutive weeks, an unusually low level that indicates companies are laying off few workers.