The major Sudden Stratospheric Warming (SSW) event predicted for about a month now is currently underway. Meteorologists are expecting brutal Arctic conditions to plunge into the US and Europe within the next 15 – 20 days.
This SSW began a week-or-so ago and is now slowly progressing from the stratosphere down into the troposphere — the lowest layer of Earth’s atmosphere. Not all SSW’s behave the same, though by mid-to-late January the impacts of this one will be known, and if it’s anything like last years expect ‘Beast from the East 2’ headlines to propagate the front pages.
The coloured lines in the above chart (turquoise and pinks) are the four individual CFS runs which take us through to the end of May.
ALL FOUR runs are showing a dramatic collapse in the Zonal winds.
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 strong 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.
A strong SSW event occurring this early in season is really quite unusual.
Winter is still 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