It’s chillingly clear the weather has been brutal this winter, and undeniable the cold and storms have stalled parts of the U.S. economy. What isn’t known – or knowable – is exactly how much the deep freeze and snowy streets have restrained economic activity.

This will be a lasting source of confusion, debate and excuse-making among economists, investors and business executives for months, complicating the interpretation of every fresh economic-data release and the handicapping of the Federal Reserve’s response to them.

As Lauren Lyster and I discuss in the attached video, the second-coldest winter since 1970, with 66% more snow than last year, has been cited by automakers for a January decline in car sales and the unforeseen drop in the ISM manufacturing index Monday, which was a catalyst of that day’s 2% stock-market slide.

Related: Baby, it’s cold outside: Will the economy get frozen?

Natural-gas bills will surge by 73% this winter, according to analysts at Sterne Agee, resulting in a potential 6% drag on consumer spending lasting into the spring, with particularly dramatic effects in the Midwest and Northeast. Casual-restaurant customer traffic fell more than 4% in January, according to industry trackers.

Investors are hoping the employment report for January on Friday will confirm broad suspicions that December’s surprisingly weak 74,000 new-job gain was mostly undercut by severe cold that month. The consensus forecast is for 185,000 new jobs in January.

But might the January chill have cost the economy some payroll gains, too? How should Wall Street interpret another weak report well below the past year’s trend?

The ADP private-payrolls release today was a modest shortfall versus forecasts, estimating 175,000 additions to the worker ranks. Mark Zandi, chief economist at Moody’s Analytics and a participant in the ADP data-crunching, said in the latest release: "Cold and stormy winter weather continued to weigh on the job numbers. Underlying job growth, abstracting from the weather, remains sturdy."

Related: Economic recovery? That's "offensive to a lot of people who are struggling," says Heidi Moore

And yet, among the stronger segments of the latest report was construction, which added 25,000 employees in the month.

This is the kind of dissonant message being heard in nearly all the economic inputs of the past few months. Retailers notoriously resort to the excuse of bad weather when sales disappoint.
Even the claims of Ford Motor Co. (F), Toyota Motor Co. (TM) and others about the freeze-out of would-be car buyers has been questioned by analysts, as Bloomberg reports.