If last week's modest drop in initial unemployment claims offered a modicum of good news, today's new report from the Department of Labor is cause for real celebration -- that is, except for the catch.

The great news is the new totals haven't just improved sharply, they've also reached a level unseen in four years. The discouraging news is, the drop is more the result of one-time factors, instead of a remarkable economic turnaround.

U.S. jobless claims fell by 26,000 last week to 350,000, but onetime factors such as fewer auto-sector layoffs than normal likely caused the sharp decline, the Labor Department said Thursday. The level of claims is the lowest in four years, although they could move higher in the next few weeks as onetime seasonal factors unwind. The four-week average of claims, meanwhile, decreased by a smaller 9,750 to 376,500. The monthly average reduces seasonal volatility in the weekly data and is seen as a more accurate barometer of labor-market trends.

To reiterate the point I make every Thursday morning, it's worth remembering that week-to-week results can vary widely, and it's best not to read too much significance into any one report. That's especially true with a report like this one.

In terms of metrics, when jobless claims fall below the 400,000 threshold, it's considered evidence of an improving jobs landscape, and when the number drops below 370,000, it suggests jobs are being created rather quickly. We've only managed to dip below the 370,000 threshold twice in the last 14 weeks.

And with that, here's the chart showing weekly, initial unemployment claims going back to the beginning of 2007. (Remember, unlike the monthly jobs chart, a lower number is good news.) For context, I've added an arrow to show the point at which President Obama's Recovery Act began spending money.