Last month, I warned you: U.S. retailers were due for a pileup on the highway to higher consumer debt. Consumer spending shot up in March, but personal income failed to keep pace, suggesting that the irresistible force of American consumerism was about to hit the immovable object of an empty wallet.

And then it happened. Same-store sales rose by a mere 0.5% in April -- barely a third of Wall Street's projections. Abercrombie & Fitch (NYSE: ANF), Aeropostale (NYSE: ARO), and Target (NYSE: TGT) all reported declines in monthly comps, and investors paid the price in falling share prices.

The U.S. Department of Commerce detailed the damage last week:

Spending

Why did it happen? As I warned in May, months of pent-up spending left the indefatigable American consumer totally tapped out. And so consumers refused to spend. But could the opposite be true this month?

Over the next couple of days, investors will be treated to a flood of monthly sales reports from the nation's largest retailers, and contrary to what we saw last month, the news this time could be good. A sharp rise in April's income looks likely to have replenished American wallets in time for May shopping. Analysts project a 3.8% rise in comparable sales figures this time around, and they might be right.

But don't go crazy
Or not. While business still seems good at some retailers -- such as Costco (Nasdaq: COST) and its 11.2% same-store sales increase in April -- last week saw American Eagle Outfitters (NYSE: AEO) confessing to seeing "weaker business trends early in the [current] quarter." Before this, Wal-Mart (NYSE: WMT) warned of possibly negative comps for the entire current quarter.

To my Foolish eye, this sets up a short-term opportunity for retail investors. Right now, the U.S. Census is in the middle of a 600,000-worker hiring spree. So I'd expect us to see another big bump -- and perhaps more than one -- in the income column over the next few months. And because these ultra-temporary jobs are by definition "pocket money" work, I wouldn't be surprised if the Census workers run right out and spend their paychecks.

Foolish takeaway
Problem is, once this money's gone, it's gone. The jobs won't last. The paychecks will stop coming. Until we see a real, sustained spike in permanent hiring, I fear we'll wind up right back where we were in April.

My advice: If retailers spike on "unexpected" good news this month and the next, use this opportunity to cash in, and cash out. This chance won't soon come again.

At least that's the way I see it. But what do you think? Take the Foolish Rorschach test, and tell us what you see in the chart up above, below.

Fool contributor Rich Smith owns no shares of any company named above. Costco Wholesale and Wal-Mart Stores are Motley Fool Inside Value picks. Costco Wholesale is also a Motley Fool Stock Advisor recommendation, and the Fool owns shares. The Motley Fool has a disclosure policy.