Atmospheric rivers (AR), elongated tendrils of highly concentrated moisture in the atmosphere, are often thousands of kilometers long. They tend to move moist air from the tropics or subtropics northward toward the pole and play a critical role in the water cycle. Though some are severe, the majority over time have been helpful rather than the reverse. Pretty much all assessments agree though that, due to global warming, ARs will become more destructive, especially under the current high-emissions trend scenario that currently obtains. There may be an increase in the number of days under an AR of between 200%-300% by century’s end and meanwhile, places like the Pacific Northwest are being drenched.