The large-scale weather pattern that's now influencing much of the USA's weather – known as an omega block because of its resemblance to the Greek letter omega – isn't budging right now.

Tuesday’s upper-level pattern is a near-textbook definition of an Omega block. You can see in the graphic below a low-pressure system over the West Coast and a second low-pressure system of the ...

Rex blocks are more complex—and more disruptive. The other type of blocking we often see in the skies above Canada is known as a Rex block. This pattern is named after Daniel Rex, an American ...