Having nothing better to do I checked FR24, Flightaware, etc. There were around 100 diversions of flights bound for JFK. I counted 18 international diversions to ORD and two to MIA (XL 1438 from Guayaquil got to the NYC area before diverting), Obviously closer alternates couldn't cope with the demand.
LGA was closed for most of the day - there were a few DL ops late in the evening.
Other flights that appear to have returned to base:
DY 7019 (CDG)
IB 6253 (MAD)
VS 25 (LHR)
Obviously the weather turned out worse than forecast, but the met guys can't get it right all of the time. At least the pilots & despatchers knew to load a lot of contigency fuel.
Last edited by Peter47; 7th Jan 2018 at 20:52.