The GFS and it’s ensembles are forecasting a dramatic reduction in westerly Zonal winds over the North Pole during the latter half of December and into January.
The northern latitudes have experienced very strong Zonal winds the last two months (Oct and Nov), which went hand in hand with the below-average temperatures recorded at the Pole:
But things look to be changing.
This last week or so, the westerly Zonal flow looks to have already begun reducing, and the 10hPa temperature at the North Pole is responding.
According to the GFS and its ensembles, by late December a serious blob of high pressure will build in the northern latitudes.
The coloured lines in the above chart (turquoise and pinks) are the four individual CFS runs which take us through to the end of March.
ALL FOUR runs are showing a continuation of the Zonal weakening that began late Nov, and by mid/late December they’re indicating a dramatic collapse altogether.
When all four runs are matched like this, it’s certainly something to pay attention to — the model is likely picking up on a sudden stratospheric warming (SSW) event, likely a result of the deep solar minimum our sun is entering.
Switching attention to the red dashed line, last year’s data, notice the sharp drop off in mid February — this coincided with Europe’s ‘Beast from the East’.
IMPACTS OF SSW
Following a sudden stratospheric warming event, the high altitude winds reverse to flow eastward instead of their usual westward.
The eastward winds progress down through the atmosphere and weaken the jet stream, often giving easterly winds near the surface and resulting in dramatic reductions in temperature across Europe and often North America to boot.
For a strong SSW event to occur this early in season is really quite unusual.
But the GFS and its ensembles have been consistent with this message for the last few months.
Stay tuned for updates.
Winter is shaping up to be a doozy, as solar activity continues its decline.
The Grand Solar Minimum is intensifying.
Weather extremes are ramping up.
We’ve known the mechanism for decades, as this 1975 article from Science News demonstrates:
Grand Solar Minimum