# Stratospheric polar vortex collapsed 18 days earlier than any record in ERA5 data since 1959

- Published: 2026-11-14 04:37 UTC
- Section: Planet › Climate
- Tags: polar vortex collapse, sudden stratospheric warming, SSW record, ERA5 reanalysis, stratospheric wind reversal, North Atlantic Oscillation, Severe Weather Europe, Andrej Flis, jet stream, Arctic cold air
- URL: https://realtech.media/news/rt-56004f53445c1679cbb92ab7_stratospheric_polar_vortex/

**Wind at about 30 km over the Arctic reversed from westerly to easterly on 10–11 November, a major sudden stratospheric warming. Its effect on European weather remains uncertain.**

![Stratospheric polar vortex collapsed 18 days earlier than any record in ERA5 data since 1959](https://realtech.media/media/2026/11/01ba4d3795360a49.webp)
*novinky.cz*

Meteorologists had warned for several weeks of a possible record-early collapse of the polar vortex, and this week it happened, novinky.cz reports. Data on wind speed and direction in the stratosphere, where a large polar vortex forms over the Arctic in the cold part of the year, confirm it. [1]

According to an analysis by meteorologist Andrej Flis of Severe Weather Europe, the decisive moment came between 10 and 11 November. At an altitude of about 30 kilometres the flow reversed from westerly to easterly. This reversal is the main criterion of so-called sudden stratospheric warming (SSW). [1]

## Record against ERA5 data

Normally this circulation is fairly stable and helps keep very cold air at high latitudes. This time, strong planetary waves from the troposphere penetrated into the stratosphere and deformed and weakened the vortex. [1]

SSW usually occurs in January or February, when the vortex is fully developed. In the ERA5 reanalysis, whose records begin in 1959, no major SSW had occurred before 28 November. The previous record, set in 1968 and 2025, was beaten by 18 days. [1]

## Possible effect on European weather

Because of the unusually early timing, the consequences are hard to estimate. According to Flis, first signals of a possible influence on the lower atmospheric layers are beginning to appear. SSW effects can gradually spread into the troposphere and alter the position and waviness of the jet stream, which shapes the distribution of pressure systems over Europe and the North Atlantic. [1]

Model forecasts now suggest stronger blocking highs and a shift to the negative phase of the North Atlantic Oscillation (NAO) at the turn of November and December. That could ease the penetration of Arctic cold air into mid-latitudes. [1]

Flis also examined similar situations with climate simulations, focusing on a combination of early SSW, El Niño and the westerly phase of the equatorial stratospheric flow. The results show a tendency toward higher pressure over northern Canada and Greenland and lower pressure over Europe. Such a pattern may support northerly flow and an inflow of colder air into Europe, with better conditions for snowfall, especially in central Europe. [1]

Whether the disruption will actually affect the onset of winter in Czechia remains uncertain. Although Flis's simulations show a fairly pronounced tendency toward cooling in Europe, current forecast models are so far considerably more restrained. [1]

## Sources

1. [novinky.cz](https://www.novinky.cz/clanek/pocasi-polarni-vir-zkolaboval-rekordne-brzy-40608511)

---

Source: RealTech, realtech.media — https://realtech.media/news/rt-56004f53445c1679cbb92ab7_stratospheric_polar_vortex/