The skies of the U.S. economy are clear and sunny, but many analysts see storm clouds on the horizon.

By many measures, the economy is in its best shape since the Great Recession of 2007 to 2009. Unemployment hit an 18-year low of 3.8% in May. Average wage growth is widely expected to reach 3% by the end of the year. And the economy is projected to grow nearly 3% in 2018 for just the second time since the downturn.

Yet the economic expansion is the second-longest in U.S. history, leading many economists to forecast a recession as early as next year. Half the economists surveyed last month by the National Association of Business Economics foresee a recession starting in late 2019 or in early 2020, and two-thirds are predicting a slump by the end of 2020.

Why?

Precisely because things seem to be going so well.

The late stage of an economic expansion is most vulnerable to a popping of the bubble. It’s typically when unemployment falls, inflation heats up, the Federal Reserve raises interest rates to cool the economy down — often going too far — and investors and consumers pull back.

Paul Davidson, USA Today, June 11, 2018