The 183 was a return due to snow, I believe there was another.
As to why did they go on the first place? My best guess would be the weather forecast valid at departure time indicated it was ok to go from an aviating POV but as the situation on the ground developed and people at JFK saw what they were really dealing with then maybe other issues came into play..
Cancellation/major delays to some the earlier BA flights outbound from JFK would have made ramp/gate space unavailable for the inbounds (gate space at the terminal BA use at JFK is very limited). If general ground infrastructure or onwards connecting flights were badly effected by the weather there might have been probs getting pax (and crew) away from JFK post arrival and the port authority might not have appreciated any more arrivals.....
In short the decision to return might not have been purely down to aircraft operating limits.
Last edited by wiggy; 5th Jan 2018 at 06:52.