For much of this winter season, the polar vortex winds at 60°N have been racing around the stratospheric polar region. During February alone, these west-to-east winds were two times stronger than normal for that time of year. However, the latest forecasts suggest that the polar vortex is about to switch gears with a major vortex disruption to happen this weekend. Read on to find out why the polar vortex could be bottoming out early this season.
Observed and forecasted (NOAA GEFSv12) polar vortex wind speeds at 60°N (bold blue line) compared to the natural range of variability (faint blue shading). Since mid-November, these stratospheric winds have been stronger than normal (thin blue line). However, that’s about to change as the latest forecasts (issued March 3, 2025) indicate the winds at 60°N are going to dramatically decrease over the next few days (bold purple line), indicating a polar vortex disruption. The big question is whether these winds will rebound toward their normal strength before the end of the season. NOAA Climate.gov image, adapted from original by Laura Ciasto.
Stratospheric pit stop
At the time of writing this post, the polar stratospheric west-to-east winds are still speeding around the Arctic [footnote #1], but forecasts suggest they are not only going to come to a screeching halt by the weekend, but they are then going to strongly reverse direction. When this wind reversal (i.e., winds become east-to-west) occurs at 60°N and 10 hPa (~19 mi/30 km above us), it’s called a sudden stratospheric warming. As the name suggests, these major polar vortex disruptions are linked to incredible stratospheric temperature increases over a short period of time [footnote #2]. For this upcoming event, temperatures in the mid-stratosphere could increase as much as 45°F (25°C) in less than 5 days.
Observed and forecasted (NOAA GEFSv12) polar cap temperatures compared to the natural range of variability (faint orange shading). Since October, these stratospheric temperatures (bold red line) have been colder than normal (thin red line). This is expected because strong polar vortex winds act as a barrier between cold Arctic air and warmer mid-latitude air. As the polar vortex becomes disrupted, the stratosphere will warm quickly and intensely (bold pink line), hence the name sudden stratospheric warming. NOAA Climate.gov image, adapted from original by Laura Ciasto.
Sudden stratospheric warming events usually come in two possible flavors in which the polar vortex either displaces off the pole or splits into two smaller vortexes. This particular event may be a bit of both. The initial warming event kicks off with the polar vortex shifted toward Europe, but the forecasts also show pieces of the vortex splitting off from the main lobes several days later.
Evolution and forecast of stratospheric conditions. Earlier this week (March 4 2025; left panel), the polar vortex winds (vec
4 Comments
rohan_
from March 6th
zeagle
Interesting article. We are past the usual -20 or lower six weeks where I am so feels like a typical year. If I choose a random northern place like Rankin Inlet NU it is still cold up there with a low of -33 tonight.
It is a sign of the times when I think huh, climate.gov… is that a reputable source?
timzaman
Very interesting article, but since it's 16 days old, seems like quite irrelevant news to hit the frontpage.
disposableuname
I can't say I even clicked through to the link – given the convulsions the federal government has been going through, I cannot trust a federal source speaking publicly on something with a strong political valence (e.g., climate) at this point.