Know doubt in my mind that without the strat responding you will not see big freezes as in Feb 56,winter63, 87, 09/10, Dec 10 etc. Whether this perculates from a minor strat warming or a full blown SSW. The strat at least up to 30mb is normally affected to see strong enough hlb's to deliver potent cold to our shores. There is a big difference also between splits and displacements. This time around we have had a split in quite a favorable way with the vortices displaced to either side of the pole and greater gph to our north. The only problem lies in the very slow downwelling.
Dispite a slight knee jerk reaction to the output yesterday and demise of the easterlies by the end of the working week I am convinced we will see a prolonged period of cold/very cold wintry weather to come. My money would be on the gfsp synoptic development, with high pressure to the east building over the top of a sinking trough and then strengthening heights to our north ushering in frigid continental Arctic air.