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[blizzard1024]

My theory is that when the baroclinicity is higher than normal in winter especially in the NH, NOT lower than normal, you obviously have colder air over the continents which can contrast more with the slower responding seasonal temperature changes of the oceans. This increases baroclinicity which leads to larger and much deeper oceanic storms which in turn eventually advects warmer air northward and eventually builds upper level high  pressure to the north and forces much colder air well south to the mid latitudes and lower heights to the south. This is when you get blocking. So when there is excess cold air in the NH high latitudes, that is when you get blocking patterns as the atmosphere forces this colder air south and warmer air north due to increased storminess. The blockiness is an enhanced wave train.

 

Weaker baroclinicity leads to weaker storms which will reduce the massive warm advections into the Arctic. But the Arctic in these situations already is NOT as cold as it would be due to a warmer season. Also in these patterns you get more zonal flow and the mid latitudes get flooded with milder oceanic air versus polar air. This makes sense because in these less baroclinic environments the wave amplitudes are weaker, which makes sense because there is less energy. The baroclinicity drives how amplified the wavetrain becomes.

 

The 1960s and 70s showed major blocking episodes and that was globally a cooler period. All this Rutgers research about global warming leading to more blocking is very suspect in my opinion.