Frontier Airlines EarlyReturns (Pre-Alignment) - East Coast weather and (lack of) flight cancellations

As of this writing, F9 510 DEN->LGA is apparently in the process of diverting to PIT, (according to their flight status page) before making a further flight to LGA about 4 hours behind schedule. Things are really messed up right now...


510
Operated by:
Frontier From: Denver (DEN)
Scheduled: 10:45 AM
Estimated: 1:45 PM
Actual: 1:55 PM
Status: In Flight
Gate: A25 To: PIT (PIT)
Scheduled: 7:30 PM
Estimated: 7:30 PM
Actual: Data Not Currently Available
Status: On Time

510
Operated by:
Frontier From: PIT (PIT)
Scheduled: 8:30 PM
Estimated: 8:00 PM
Actual: Data Not Currently Available
Status: On Time
Gate: To: New York (LGA)
Scheduled: 9:20 PM
Estimated: 8:50 PM
Actual: Data Not Currently Available
Status: On Time

Update: 511 (510's return) was cancelled, along with 513 (the 9:40 LGA->DEN) and 516 (the 3:15 DEN->LGA). What did they do with the extra aircraft that ended up at LGA... ?