Latest stratosphere analysis charts from the JMA show that temperatures have risen somewhat in the past three days at 10hPa and 30hPa. 30hPa temperatures have gone back to average whilst 10hPa temperatures remain on the cold side. With the forecasted healthy Polar Vortex, expect these temperature charts to drop back down again.
Latest GFS does not hold any promise on the Polar Vortex changing any time soon with cooling taking place then flat lining.
GFS ensembles agree with the operational run too as shown by the diagrams below.
It's not all negatives for cold lovers though as it's better to have the Polar Vortex locked in undisturbed over the North Pole through this period as it's a cooling time of year. As it's locked in, the cold can get deeper and deeper. When northern blocking does form sometime in Winter or Spring then, the cold can be more extreme than say if you were to have the northern blocking beginning in Autumn.
Some interesting charts from GFS runs today mind you in Fantasy Island*. The 0z showed a Greenland High and a northerly flow forming bringing down 850hPa temperatures between -5 to -10c on November 22nd/23rd. The 06z showed a very stubborn area of high pressure near Russia and Scandinavia of up to 1050mb. Not affecting us on the run as we're under high pressure also but it could have been the start of nature's teasers for what was to come if it were to verify.
*Note: Fantasy Island so will change in next runs of the model and is shown just for fun.