12z EPS N hem 500mb run-run change from day 7 onward. Notice the trend to more -NAO that begins in the medium range & propagates forward throughout the run.
— Eric Webb (@webberweather) January 11, 2021
-PNAs like the one being shown by ~ day 10 don't have the same meaning when it's coupled with a giant west-based -NAO pic.twitter.com/6zxT3h7Qeh