On Sunday, just 7 of 64 members indicated a split of the Stratospheric Polar Vortex during early January. Each day, we've seen an increase of this number. Monday was 8, Tuesday up to 17, and now today is at 21 members. pic.twitter.com/R1PnSzAmeM

— Mike Ventrice (@MJVentrice) December 19, 2018