From the GRR AFD this afternoon:
We will also be watching model trends with a potential clipper on
Thursday or Friday followed by extreme cold for next weekend. The
ECMWF has been going ballistic the past couple days in painting
historical (hysterical?) outbreaks of arctic air across the Great
Lakes and surrounding areas. That signal is also in other models
but not as strong. Even so, highs around 10 above and lows 10
below are well within the realm of possibilities by the end of
the week.