Updated

WASHINGTON -- The number of people applying for unemployment benefits plunged last week, reversing a spike from the previous week largely caused by harsh winter weather.

Applications for benefits dropped by 42,000 to a seasonally adjusted 415,000 in the week ending Jan. 29, the Labor Department said Thursday. They had surged in the previous week after snow storms in the South disrupted work and led to temporary layoffs.

Applications are well below their peak of 651,000, reached in March 2009, when the economy was deep in recession. Fewer than 425,000 people applying for benefits is consistent with modest job growth. But applications will need to fall consistently below 375,000 to signal a likely decline in the unemployment rate.

Last week's decline resumes a downward trend that took shape late last year. The four-week average, a less volatile measure, fell steadily in the last three months of 2010 to a two-year low of 411,250 in the week ending Jan. 1. That raised hopes that employers, operating with lean work forces, would soon step up hiring.

The average rose in January, mostly because of seasonal factors, such as the harsh weather and the layoff of temporary holiday employees. The average ticked up last week by 1,000 to 430,500. Many economists consider data in January to be less reliable because of seasonal fluctuations.

Unemployment applications reflect the level of layoffs, but can also indicate whether companies are willing to hire.

Despite the decline in unemployment benefit applications, employers have been slow to add jobs. 
One factor holding back job gains is that workers are becoming increasingly efficient and productive. That enables companies to produce more without hiring more workers.

In a separate report Thursday, the Labor Department said that productivity, the amount of output per hour worked, rose 3.6 percent in 2010, the biggest increase since 2002.