Could be the season/s final stratospheric warming event.
Images from 15-FEB-17 ECMWF run.
Weak high-altitude zonal flow returns after the recent SSW event.
Flow above 30 mb reverses and strengthens as the PV is once again displaced.
Flow throughout the depth of the troposphere (evidence of the downward propagation from the previous SSW?) also reverses.
Stratosphere Diagnostics courtesy Freie Universität Berlin