Normally there is a time lag before the -ve u wind anomalies hit the trop following the #ssw . The +ve U wind need to be flushed out of the system. But the mid-lower strat +ve u wind very weak this year, so quick propagation likely imo pic.twitter.com/POkpz1LjSe

— Ed O'Toole (@chionomaniac) January 2, 2021