Due to the NOTAMS (Notice to Air Mission Systems) failure, the FAA issued a nationwide ground stop for all flights within the United States with the exception of medevac and military flights. The ground stop which took effect at 0730 Eastern time and is estimated to last two hours, until 0930 Eastern time.

FAA NOTAMS UPDATE
The FAA has provided three updates and more are expected as they bring the NOTAMS back online.
Those interested may follow the FAA on Twitter for their periodic updates or directly on the FAA’s National Airspace Systems Status site: FAA Site