From an email blast of the USCIS:
Please be advised that due to the impending snowstorm […], United States Citizenship and Immigration Services is acting to cancel all existing appointments for benefits and services […] for Wednesday, January 12th. We are in the process of individually contacting as many customers as we can to advise them that their appointments will be rescheduled as soon as possible. We ask that you further circulate this message to concerned parties in your service area.
Thank you in advance for your cooperation
We suggest to contact USCIS prior to any trip to confirm that they are open. As always, it is important that USCIS has your current contact information. It is the law to notify and relocation timely to USCIS.
und viele Grüße aus Charlotte
Reinhard von Hennigs