“Crazy cold.”

It may not be the official scholarly terminology among professionals in the field, but coming from the mouth of Weather Underground founder Jeff Masters it seems about right to capture the mood this winter in Michigan and much of the eastern half of the U.S.

And, for sure, in the final week of January, throughout much of the deep south and along the Carolinas and mid-Atlantic seaboards. That’s all in harsh contrast with the prolonged drought plaguing much of California and the heat toasting much of the U.S. from the Rockies westward.

“Blame the jet stream,” Masters and a number of respected meteorologists and climatologists say in this month’s installment of The Yale Forum’s “This is Not Cool” video, by independent videographer Peter Sinclair.

Through a series of clips from across the country and across the ocean, the latter depicting severe storms slashing into the United Kingdom in December, the timely video serves up a well-sourced every person’s guide to understanding the bone chilling and often snowy days of January. It provides the meteorological explanation for them and outlines them also in the context of a warmer climate globally.