GEFS accelerates this pattern change relative to the EPS likely due to faster CC Kelvin Wave progression thru the WP. Canonical progression of -EPO/+TNHs & tropical forcing suggest the W US &/or Rockies will turn cold before the E US does. I'd wager the E US flips ~ Jan 5-10 ish. https://t.co/btNYDF5uFa

— Eric Webb (@webberweather) December 17, 2019