JPG wrote in
:

Not much momentum in the stratosphere I would have thought, given the
low pressures, so my "first principles" thinking would suggest that
the influence of stratospheric winds would not be very significant.

There was an article in Nature about this a year or two ago - using
stratospheric circulation to forecast what's going to happen in the
troposphere - the two seemed to lag by about 30 days if I recall. Was quite
good for forecasting blocked episodes and periods of strong zonal activity.
I think Waghorn posted the links if I recall - Mr Waghorn?

Cheers
Richard