In terms of data the last few gfs runs have been missing some automated aviation data from ARINC, this would probably effect all the models though. NOAA talk about critical and non critical data, the question is though is critical here meaning a model run has to be dumped or in terms of non critical does this mean the model run can go ahead and be accepted but with a likely higher error rate or forecast variability.
The variable here is that the Arctic area of the North Atlantic has a lack of observational data anyway and this has been commented on previously by NOAA, the upcoming pattern relies on the models calling this area correctly, they could overplay or underplay the extent of blocking in those regions. Given that the models can't even agree on events upto 96hrs i think many members are expecting too much from them, we need to wipe the slate clean here and start again focussing on the small changes within the 96hrs range that will snowball into large scale differences later.
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