Even if you get regular mammograms, knowing possible cancer symptoms is important. Thickening of the breast and nipple changes can also be signs.

Winter is coming—eventually. And while the Earth is warming, a new study suggests that the atmosphere is being pushed around in ways that cause long bouts of extreme winter cold or wet in some regions.

The study’s authors say they have identified giant meanders in the global jet stream that bring polar air southward, locking in frigid or wet conditions concurrently over much of North America and Europe, often for weeks at a time. Such weather waves, they say, have doubled in frequency since the 1960s. In just the last few years, they have killed hundreds of people and paralyzed energy and transport systems.

The new paper, titled “Recent Increase in a Recurrent Pan-Atlantic Wave Pattern Driving Concurrent Wintertime Extremes,” appears this week in the Bulletin of the American Meteorological Society.