The sweeping pattern that's now influencing much of the USA's weather is called an omega block because of its resemblance to the Greek letter.

A strange atmospheric pattern known as an "omega block" is preventing the usual eastward progression of weather across the U.S. — but what is this weird block, and when will it go away?

It’s about to rain for days in eastern states because of an unusual atmospheric phenomenon known as an omega block.

Find out whether flooding or severe storms are possible where you live this week as an uncommon phenomenon known as an omega ...

“The main threats are large hail, damaging wind gusts ... Plains into the southeastern U.S. Omega blocks can persist for several days to over a week, leading to prolonged periods of unusual ...