Rare polar vortex split forecast for February 2025 could bring prolonged cold to North America
A significant cold outbreak is forecast for mid-February 2025 as a Sudden Stratospheric Warming (SSW) event splits the polar vortex, with one of its cores expected to move into North America.
startobserve polar vortex modelrun feb12025 valid feb162025
Image credit: Z. D. Lawrence (NMT)
A significant Sudden Stratospheric Warming (SSW) event is forecast for mid-February, potentially disrupting the polar vortex, and bringing prolonged cold outbreaks to much of the United States.
While North America is expected to experience a cold outbreak, the effects on Europe remain uncertain due to the polar vortex’s less direct influence in the region.
The polar vortex is a large, persistent circulation of cold air located in the stratosphere over the Arctic. It is strongest in winter and helps to contain frigid air within the polar region. When the vortex weakens or splits due to stratospheric warming, the disrupted air masses can move southward, impacting mid-latitude weather patterns.
Recent model projections indicate a major sudden stratospheric warming (SSW) event in early February 2025, potentially leading to a rare split of the polar vortex, according to an analysis by Andrej Flis of Severe Weather Europe. This process involves a rapid rise in stratospheric temperatures, weakening the vortex and sometimes breaking it into two or more smaller circulations known as “daughter vortices.”
According to Flis, one of these daughter vortices may shift over North America, increasing the likelihood of Arctic air intrusions into the United States and Canada.
While the exact regions affected remain uncertain, past events of this nature have led to prolonged periods of below-average temperatures and winter storms.The polar vortex is currently at or above its typical size and is stronger than usual. This image illustrates the geopotential height and temperature in the mid-stratosphere at the 10 mb level (30 km/18.5 miles). Image credit: SWE
Similar stratospheric warming events have been linked to severe cold outbreaks, such as those in early 2021 and 2018, which brought extended freezing conditions to large portions of North America. However, not all vortex disruptions lead to extreme cold. The degree and timing of tropospheric coupling—the interaction between the stratosphere and lower atmospheric layers—play a key role in determining surface-level impacts.
If the expected split occurs and successfully influences the tropospheric jet stream, parts of the Midwest, Northeast, and even the Southern United States could experience increased cold outbreaks in late February and March. Canada, particularly central and eastern regions, may also face prolonged winter conditions.
Similar stratospheric warming events have been linked to severe cold outbreaks, such as those in early 2021 and 2018, which brought extended freezing conditions to large portions of North America. However, not all vortex disruptions lead to extreme cold. The degree and timing of tropospheric coupling—the interaction between the stratosphere and lower atmospheric layers—play a key role in determining surface-level impacts.
If the expected split occurs and successfully influences the tropospheric jet stream, parts of the Midwest, Northeast, and even the Southern United States could experience increased cold outbreaks in late February and March. Canada, particularly central and eastern regions, may also face prolonged winter conditions.
