Fresh back in D.C. from a Colorado ski vacation, it strikes me that the treacherous year ahead that we confront – littered with political, economic and security risks – presents all the challenges of a double black diamond ski run.

Those slopes are signposted as such to warn skiers of an approaching terrain that is steeper, narrower, and bumpier than all but the most expert skiers can navigate, made even more unpredictable by frequent weather changes. Their bone-rattling obstacles are seen (trees) and unseen (snow-covered boulders).

That's a good metaphor for a year during which volatility may be the only certainty for policy makers, business leaders and investors. That may be good news for the ilk of hedge funds that are designed to capitalize from price swings, and thus this could be a bumper year for them. For most of the rest of us, expect months of handwringing and headaches.

The first few days of 2019 have already set the tone.

Stock markets have sunk and soared in the first days of trading, falling on growing fears of a global slowdown and the economic hit of U.S.-Chinese trade tensions, only to rise again on good U.S. job numbers or encouraging Trump tweets. Yet risks lurk behind every global corner.

Will the Trump growth story turn belly up in the face of domestic turbulence: the Mueller investigation, the threat of impeachment and Fed interest rate policy? Will the United Kingdom crash out of the European Union or remain through a "peoples vote"? Will the U.S.-China trade fight end in a deal or escalate into something worse? Does U.S. troop withdrawal from Syria signal a less predictable U.S. ally?

And so on.

The list of risks is a growing one. A good many experts have already provided their "top ten" for 2019. Rather than add my own, here instead are five historic inflection points to watch, a handful of history-bending shifts this column will track in the months ahead.