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 ...

An omega block weather pattern is causing heavy rain and severe thunderstorms, particularly in Texas. Heavy rain is expected to worsen existing river flooding and cause flash flooding.