Updated from 8:15 a.m. EST

Weak February sales results from retailers Thursday reignited concerns about the health of consumer spending, after a big snowstorm in the Northeast helped to bury the previous month's momentum.

Ken Perkins, president of market-research firm Retail Metrics, said 62% of the retailers that make up his firm's sales index missed expectations. That marked the first time a majority of companies in the index have missed monthly estimates since last July.

"There was clear weakness in the teen apparel space, with Abercrombie & Fitch ( ANF), Hot Topic ( HOTT), Pacific Sunwear ( PSUN) and Aeropostale ( ARO) all missing estimates," Perkins says. "That's the weakest performance by them in over 18 months. On the other hand, the bulk of the department stores did a bit better than expected, and the discounters fared relatively well also."

Perkins' overall index, which tracks results from more than 60 national chains, met expectations, with a gain of 3.1% over last year.

"It's a bit of a fluke, since the index is chain-weighted and larger retailers did okay," Perkins says. "Considering all the shortfalls though, I think you have to characterize the month as a disappointment."

Richard Hastings, a retail analyst with Bernard Sands, says some retailers made tactical mistakes managing their inventories after a stretch of unseasonably warm weather in January.

"Many apparel retailers tried to decrease inventory levels to avoid price erosion on winter clearances," Hastings says. "The assortments weren't there when cold weather snapped back and shoppers were looking for something other than a bikini to match their mittens."

Recent data also suggest that economics may have played a role in the disappointments, as consumer confidence fell more than expected in February on concerns about fuel prices and the job market. Meanwhile, the housing market continues to show signs of slowing as interest rates rise.

The world's largest retailer, Wal-Mart ( WMT), confirmed the 3.2% rise in February same-store sales, or comps, it previewed last weekend, but said same-store sales won't rise by more than 3% in March.

"Easter is three weeks later this year, which will likely result in a weaker March and a stronger April," Wal-Mart said in a statement.

Wal-Mart's chief rival, Target ( TGT), said its comps rose 3.6%, which was in line with Wall Street's expectation, according to Thomson First Call.

Same-store sales are a key retailing barometer measuring sales at stores open for at least a year.

Abercrombie & Fitch, Wall Street's hottest teen-clothing retailer, fell short of estimates, saying February comps rose 5.9% from a year ago, compared with analysts' average prediction for 13.9% growth.

Among other disappointments was Talbots ( TLB), which said February comps slid 6%; Pier 1 ( PIR), which posted a 10.8% decline; and New York & Co. ( NWY), which said same-store sales plunged 12%.

New York & Co. also lowered its earnings guidance, saying it expects to post a profit of 20 cents to 23 cents a share in its January quarter, well below the 36-cent analyst consensus. The company said "the strategy that had worked for us during the fourth quarter of driving sales using price incentives on targeted items failed to generate the additional transactions necessary to make up for lower pricing." The company's shares recently slid 15%.

Another blowup was at Gap ( GPS), which said same-store sales plunged 11% due to weakness at its Banana Republic and Old Navy divisions. The decline was roughly twice as bad as analysts had feared.

"In February, traffic worsened versus fourth quarter trends, which caused lower unit sales velocity," the company said. "This led to significantly lower merchandise margins."

Chico's ( CHS) said late Wednesday that its comps rose 5.7% after analysts had predicted a gain of 8.7%.

Doing better was Costco ( COST), which on Thursday reported an 8% jump in February comps and better-than-expected second quarter earnings; Dress Barn ( DBRN); and Wet Seal ( WTSLA), which said same-store sales rose 29.3%.

Also, Federated Department Stores ( FD) posted an unexpected same-store sales gain of 1% after analysts had predicted a decline of 0.9%.

Federated's smaller rival, J.C. Penney ( JCP), said February comps rose 2.3%, slightly better than expected, and forecast an increase in the low single digits for March.

Another department store favorite, Nordstrom ( JWN), reported a 4.9% same-store increase, surpassing estimates for a 3.5% gain.

Several teen-focused retailers reported mixed February results Wednesday.

Casual-clothing chain Aeropostale reported a 5.4% decline in February same-store sales, while total sales rose 14% to $67.8 million, from $59.4 million.

Hot Topic's February same-store sales fell 8.4%, pulled down by weakness in the men's and accessories categories. The company, a mall-based seller of music-related items, said total sales rose 5% to $48.4 million.

Zumiez ( ZUMZ), however, turned in another month of huge sales growth. The seller of extreme-sports clothing and accessories said its same-store sales jumped 28% in February. Total sales grew 53% to $14.4 million, from $9.4 million.

American Eagle Outfitters ( AEOS) also provided a bright spot, with same-store sales growth of 6%, beating expectations for a 4.1% increase.