A significant Arctic cold outbreak is forecast to spread across much of Europe in the days ahead, ending unusually warm winter season. The cold is expected to last through the end of March, with another blast expected at the beginning of April. Prolonged, dangerous frost conditions are likely in many parts of the continent.
Although a wide swath of Europe is experiencing unusually warm period this week, a major change is set to come this weekend as the North Atlantic Oscillation (NAO) turns into a negative phase, giving way to a strong upper-level ridge over the Atlantic and expanding into Europe over the weekend, Severe Weather Europe (SWE) meteorologists said.
"A powerful Rex block pattern develops with an increasing potential for a significant Arctic cold outbreak from northern Russia into eastern and central Europe this coming weekend. Much colder air mass at the surface could also spread towards western Europe. This will develop dangerous frost conditions for early blossoming trees. But more importantly, it could worsen the ongoing COVID-19 pandemic outbreak," SWE said.
"The pattern change over Europe is quite obvious on the forecast charts-- deep troughs over the North Atlantic will be replaced with strong ridge and surface high-pressure system," said SWE.
Over the weekend, the upper ridge extends into the northern half portion of Europe, intensifying into an extensive Rex block. SWE said this boosts the surface high-pressure system beyond 1 040 hPa after Sunday, March 22.
"The ridge will be gradually drifting its center towards east-southeast, with also a deepening upper core along its southeast flank moving towards central Europe, allowing advection of Arctic air mass with the northeasterly flow towards central Europe and potentially even further west," SWE added.
While global models are yet to release a more accurate track of the deep upper low, both the European ECMWF and American GFS models are hinting a very major cold outbreak for late March, but there are important differences.
The ECMWF model indicates that the sore of the outbreak will spread across eastern Europe, the Balkans and Mediterranean; the GFS model, on the other hand, is simulating the core more towards the central region of Europe.
The outbreak starts over the weekend across Russia, said SWE, in response to an intensifying Rex block and an associated powerful, high-pressure system over the northern half of Europe.
Through the early days in the coming week, the Arctic cold air mass will sweep across eastern Europe, towards central Europe.
Temperatures are expected to be around 10 to 15 °C (18 to 27 °F) colder than usual, which is considered very extreme for the end of the month of March.
Featured image: GFS 850 hPa temperature anomaly for March 25, 2020. Credit: GFS, Tropical Tidbits