From the 2020 thread
GFS (and other models) are showing a wave of low pressure develop and ride up along the strong cold front projected to move through. It's all heavily timing dependent, front has to clear just as the wave moves past your latitude then deepen and slow the progression of the front to see those big totals. Don't get invested in anything you see with this, it won't be resolved until very short lead times.
That's the difference in 2020. This is a totally different set up