It’s a tale of two continents. While temperatures have remained above normal all winter long in the U.S. and North America, much of Europe recently flipped from a mild pattern to its coldest in 20 years.
The cold in Europe
Consider all of the following...
* At least 450 deaths have been blamed on the cold weather (Reuters), mostly in central and eastern Europe - a large fraction in the Ukraine
* Much of the Danube river is iced over, halting or restricting navigation in Serbia, Croatia, Bulgaria, Romania, Hungary, and Austria; Bulgaria set a new record low of -28.6 C (-19.5 F) this morning (Reuters)
* 93 stations from the Czech Hydrometeorological Institute reported record low temperatures on February 5 (Bloomberg via Climate Central)
* Up to 8” of snow fell in Rome last weekend, the most since 1986 (AP)
* Paralyzing snow has cutoff entire villages in northern Italy, Serbia and Bosnia
* More snow and extreme cold is expected in northern Italy into the Balkans Friday into the weekend as a storm drops southward. The Toronto Star reports “Rome’s mayor has ordered schools in the Italian capital closed on Friday and Saturday as more snow and frigid temperatures are expected in the forecast.”
* The cold and snow extended into Northern Africa last weekend: 2-3” of snow fell in Tripoli, Libya, perhaps the most since 1956 (Wunderground); 4” fell in Algiers, Algeria - the first snowfall in 8 years, and the most in decades (Reuters)
The mild air in the United States
Now consider this...
* January was the 4th warmest on record (since 1900) and 3rd least snowy in the last 46 years (NOAA)
* The Great Lakes have much below average ice cover, especially Lake Erie
* For only the 2nd times in 106 years of records, Chicago has yet to drop below 5 F. (ChicagoWeatherCenter)
* Almost the entire mid-Atlantic and Northeast U.S. has received less than 50% of its average annual snowfall, with many observing stations well less than 30% (Capital Climate)
What’s the cause of the pattern?
The UK Met Office offers a nice explainer for the extreme cold in Europe and it relates to an area of “blocking” high pressure that has set up over Scandinavia and northwest Russia:
Easterly winds on the southern edge of this system has transported cold continental air westwards, displacing the more usual mild westerly influence from the Atlantic Ocean all the way to the British Isles.
A ‘blocking anticyclone’ [or high pressure area] can be thought of being like a very large boulder in a stream. This boulder acts like a damn, stopping the flow of the stream. In this instance a block stops the more normal westerly flow that brings milder conditions, allowing colder conditions to win out from the east.
For the large parts of North America to get cold, we need such a ”block” to set up over Greenland. That has not happened thus far this winter.
Climate Central: What’s Causing the Deadly Cold in Europe?