Update: 2 p.m. Subway service is expected to run close to normal for the evening commute, except the Franklin Avenue Shuttle, which is still suspended this afternoon, MTA spokesman Kevin Ortiz said.
The agency is also working to get all its buses back on the roads.
"Essentially we're working in conjunction with Sanitation and letting them properly plow streets to get service going," Ortiz said.
Meanwhile, MTA Chairman Jay Walder reported at a new conference this morning that the heavy snowfall forced the agency to cut off bus service around midnight and some train service in southern Brooklyn early this morning.
He called it "an orderly suspension" of service.
"We didn't send more trains out...and where we had trains, we tried to get them to the end of the line or get them back to Manhattan where they were underground," Walder said.
He acknowledged that there were some trains stuck for "short periods of time," but "there were no trains stuck overnight."
Subway service was restored by around 7:30 a.m., he said.
Update 10:45 a.m. MTA.info is back up again. Every subway line is showing delays or service changes, and bus routes are gradually being restored.
Update 8:15 a.m. The MTA is starting to resume bus service in Queens, and most train service is running, except parts of the Q line in Brooklyn, according to NYC Transit tweets.
MTA.info is still experiencing problems. Check out NYCTSubwayService on Twitter for your specific route.
Some 19 inches of snow fell in Central Park from Wednesday into Thursday, according to reports.
Earlier: A day after announcing that it would cut service during bad storms, the MTA has done just that.
Bus service throughout the city is suspended because of poor road conditions, and some outdoor train lines have been halted to clear snow and ice.
There is no train service in the Rockaways in Queens or to Brooklyn's Stillwell Avenue Terminal. There are also no trains running between E.180th St. and Dyre Avenue in the Bronx.
The agency has told riders to go to mta.info for updates on service changes, but MTA officials acknowledged this morning there have been problems with accessing the webpages.
Follow NYCTSubwayScoop on Twitter for minute-to-minute updates.