Fast bias for synoptic features at mid-ranges (is bad at forecasting slow-moving or stalled highs and lows in the mid-to-upper atmosphere in the 3-7 day forecasts)

Oh man this for sure. Lost count of the number of developing troughs the GFS has hitting the PNW 4 days out only for them to stall out or retrograde NW in the mean time resulting in the precip arriving 12-24 hours later than the initial solution. Really struggles with the first precip event after a ridge up there too, always underestimates how much work the incoming moisture has to do to overcome the dry air in place at the low levels. Not super uncommon to see it output 0.10" QPF in spots less than 24 hours out and have it end up as virga in that scenario...