Under normal circumstances, Wall Street would be preparing to parse through September's retail sales report Thursday morning - but these aren't normal circumstances.

The federal government shutdown, inching toward its third week, has postponed many official data releases, including one of the more important monthly gauges into consumer health. The lack of data is posing a problem for investors, economists, and policymakers alike, given the Federal Reserve's data-dependent focus when it comes to setting interest rates.

Federal Reserve Chair Jerome Powell acknowledged that challenge on Tuesday, speaking at the annual meeting of the National Association for Business Economics in Philadelphia. But, he added, the Fed is routinely reviewing a variety of public and private sector data that have remained available.

"Based on the data that we do have, it is fair to say that the outlook for employment and inflation does not appear to have changed much since our September meeting four weeks ago," Powell said. "Data available prior to the shutdown, however, show that growth in economic activity may be on a somewhat firmer trajectory than expected."

When it comes to retail sales, third-party data suggests that consumer conditions remain "relatively sanguine on an absolute level," writes Ivan Holman, a consumer specialist at Bernstein. That said, there are signs that spending slowed slightly toward the end of summer, especially among lower-income and younger consumers, he added.

The Chicago Fed's advance retail trade summary reports that retail sales excluding car and car parts are projected to increase 0.5% on a seasonally adjusted basis in September from August, and 0.2% when adjusted for inflation. The report combines eight weekly indicators for weekly retail sales -- including card transactions, foot traffic, and gasoline sales -- to provide an early snapshot of national spending ahead of the official retail sales report.

Retail sales excluding vehicle and car parts rose 0.7% in August from July, according to the official report the Census Bureau released in September. Total retail sales rose 0.6% in August.

The median consensus estimate for September's report for total retail sales is a 0.4% month over month increase, according to FactSet.

Bank of America's credit and debit card spending data also reflects a slight slowdown. On a yearly basis, spending was up 2% year over year in September, and 0.2% on a monthly basis, an increase BofA U.S. economist Aditya Bhave describes as "modest." Several categories recorded meaningful declines on the month, including online retail, department stores, furniture, and clothing.

Bhave cautions against putting too much weight on a September slowdown, noting that any weakness in the report could be a function of seasonal adjustment factors, rather than a sign that spending has pulled back significantly, given the strength in spending from June to August.

"Even if the September retail sales report is as soft as we are projecting, we'd caution against jumping to the conclusion that spending is starting to feel the effects of a weaker labor market," Bhave writes in a research note.

Indeed, recent comments from big bank executives suggest that consumers' financial health is steady. Executives from Wells Fargo and JPMorgan Chase both noted that delinquencies improved throughout the third quarter and that spending has held up because income growth has generally kept pace with inflation and debt levels.

"You see strong consumer spend and stable deposits and those things just kind of paint a picture of a consistently strong consumer, even though what you read about is -- it would lead you to believe that they're being more cautious, our results just say that there's a high degree of consistency there without any real pockets of slowing," Mike Santomassimo, Wells Fargo's chief financial officer, said on an earnings call Tuesday.

JPMorgan CFO Jeremy Barnum said something similar on the bank's earnings call Tuesday, noting that the "current facts on the consumer side" show that Americans are resilient, spending is strong, and delinquency rates were below expectations.

Barnum did acknowledge, however, that there are risks to consumer health ahead -- particularly a starker labor market deterioration, which could lead to worse consumer credit performance.

"There are risks and that the fact that things are fine now doesn't mean they're guaranteed to be great forever," Barnum said.