The Unpredictability of a Disrupted Stratospheric Polar Vortex

Recent stratospheric disruptions appear in the forecasts but continue to confuse global models.

• Large polar vortex anomaly is confusing the model outlooks.

• 25-28th July System remains highly divergent on the models.

• Last few days of July also look to carry potential as the polar node fades and transitions eastwards.

In recent weeks we’ve seen a rare event unfold in the stratospheric polar vortex (PV), known as a sudden stratospheric warming (SSW) event. Only a handful of these have been recorded in the last four decades 2002, 2010, 2019 and now in 2024.

This years event is turning out the be the earliest on record, where it has occurred mid-winter with an unpredictable outlook on the horizon.

NOAA’s forecast (green trace lines) and observed polar vortex temperature at 10 hPa. With the observed temperature trace (red) exceeding the ‘maximum’ range (top black trace), this large anomaly appears to confuse models given the limited precedence. Source: NCEP/NOAA

Debunking The Polar Vortex Mistruths

Before we break down the possibilities of this event, let’s look at what the polar vortex is and how it can impact the Southern Hemisphere winter.