Time for a long #wx #gif loop; focus on possible #US #christmas #cold shot. A complex multi-step process:

1)#MJO convective outflow enhances NPAC jet
2)#AWB induces #PVS, picking up moisture n/ Hawaii
3)Ridge building forms omega block over #Alaska
4)#TPV forced S w/ arctic air pic.twitter.com/BqQyHnA3ip

— Philippe Papin (@pppapin) December 18, 2017