-39.3 C 700 mb coldest temperature of winter to date, where?: White Lake Michigan USA

~The entire Arctic winter of 2018-19 was never colder at that altitude.
~Until next day in Siberian Russia
~North American continent is easily capable of creating such temperatures
~Provided less snow insulation covering ground frozen hard from extensive exposure at the peak of darker winter, from a just prior warmer or late coming winter,  a barer dark lit Great Plains ground is onto itself a byproduct of Antthropological Global Warming (AGW).

    The specific heat capacity of dry soil is less than snow or ice, it means soil can loose (or gain) its temperature quicker,  especially if continental snow coverage has been reduced:

                                                 
     ASCAT 02/28 2019 gives a good idea of where the snow lies,   it shines bright white here,  there are many locations with scant coverage namely the Prairies or the Great North American Plains:

  January 29 2019 winds over none existent forests areas (link)  coincided with the 700 mb flow hitting  the State of Michigan (link).  Consider also vast American deforested farmlands adding to different specific heat capacity characteristics of the landscape.  Note ,  same day entire  North American Arctic was warmer than Michigan at that level as well,  even for since the start of winter (from actual Upper Air measurements)!  This is a very compelling bit of evidence suggesting that vortices within the Arctic Polar Vortex,  may take quite independent temperatures then the rest of the APV.    I call one of these vortices simply as a vortice.  Usually a Southern NE American vortice becomes rogue because it is pushed Southwards by Quebec\Labrador massive cyclones ascending towards Baffin Bay,  which also warms a great chunk of the Polar Vortex concurrently,  cutting off the Southern vortice to be on its own, thus a rogue.  The idea suggesting the jet stream pushing down a rogue vortice has long been accepted as the reason why they are displaced,  but a vortice is usually part of the Polar Vortex where the jet stream is at its perimeter,  not within.

   As the world warms extreme weather increases because the Polar Vortex is shrunken and or stretched. 

         To make this evident,  consider thinner Arctic Ocean sea ice warming the Upper Air directly above.  Observing what happens to the Upper Air there is key.  What has and is happening is Arctic Polar Vortex stretched to from Maine towards Northern China, on the Axis aligned with Greenland to Vladivostok.  The core of the Vortex is hollowed over this Ocean once frozen with mainly 10 meters of sea ice, now reduced to 1.5 to 2 meters.   therefore the Polar Vortex of late is usually stretched and can split in two,  especially  during a warm winter similar to 2016.    The weather of the Northern Hemisphere is thus rapidly changing by the shrunken Polar Vortex which favors the winter warming of Alaska and Norway,  but cooling at times of Central Southern Russia  and Midwest North America during winter.  As an example I use the Polar Vortex event of January 29 2019:

                             White Lake         Fairbanks
                            Michigan  USA  Alaska USA
January 29              -19.7                     -11.5
January 30              -39.3                      -9.5
January 31              -28.3 C                  -16.5   700 mb temperatures.

      The North was and is very often warmer some 3000 Southwest miles away

    It is very possible to have such extreme events given the right circumstances.   However winters great deep freezes well South of the Arctic are furtive,  they may not be long lasting,  as White Lake's current +9C weather may attest, compared to Fairbanks current -13 C even still warmish.  As AGW increases,  the weather in many places in the Northern Hemisphere will get even more strange and extreme. WD February 3 2019