Updated 4:28 p.m.

Winter Storm Orlena blanketed the Boston area in snow Monday, with more than a foot expected on Monday and Tuesday.

Gov. Charlie Baker said the state could expect 12 to 18 inches inches of heavy, wet snow through the duration of the storm. He urged drivers to stay off the road as much as possible starting mid-afternoon Monday.

The storm could also bring with high winds with gusts of up to 55 miles per hour along the coast and the possibility of moderate coastal flooding, accordinf to Baker.

Boston Mayor Marty Walsh also urged residents and commuters to avoid driving in the city.

“I encourage everyone to stay off the roads, if at all possible, from pretty much right now until tomorrow,” Walsh said.

The National Weather Service echoed Walsh's warning, saying in a winter storm warning that "travel could be very difficult to impossible."

A snow emergency went into effect in Boston at noon Monday, which means parking is forbidden on main roads with snow-emergency restrictions. A full list is available at Boston.gov, along with discounted options for lots and garages where vehicles can be stored until the snow emergency is lifted.

Boston has 42,000 tons of salt available for spreading, Walsh said, and the ability to dispatch more than 700 vehicles to respond to the storm.

Most of the MBTA is operating on a normal weekday schedule.

Boston Logan International Airport advised passengers to check their flight status. On Monday afternoon, the airport's website showed dozens of canceled arrivals and departures.

The Massachusetts Emergency Management Agency reported 77 customers without power as of 2 p.m. Monday.

The storm is already disrupting the city's COVID-19 vaccination plans. The Reggie Lewis Center in Roxbury had been scheduled to open as a mass accination site today but all appointments are being rescheduled for the same time on Monday, Feb. 8, because of the weather.

Fenway Park, currently functioning as another mass vaccination site, was open as of Monday morning. Walsh said anyone with an appointment would be notified if plans changed.

"We're also asking people with scheduled appointments to arrive early if you can," Walsh said.

Speaking to reporters Monday, Gov. Charlie Baker said that the snow may postpone some appointments but won't harm the state's COVID-19 vaccination plan.

"This is obviously our second major storm of the season," Baker said. "We're used to dealing with snow this time of year, but it's important for folks to take this one seriously due to the heavy snowfall, the high winds and the speed with which a lot of this snow is going to fall when it starts to come down."

The governor said COVID-19 vaccine providers who have closed their doors for the storm will contact patients with appointments to reschedule them.

"I think the big goal for the mass [vaccination] sites is going to be to try to get as many of the folks who are scheduled today through, and they've been talking to people all morning about that. Folks who either are nervous about traveling in, given the storm and all the rest, they will do what they can to get them rescheduled this week," Baker said.

While activating it's usual snow-fighting operation, MassDOT will coordinate with vaccination sites to remove snow from entrances and parking lots to maintain access to the sites.

Baker also said that most vaccination sites have already received their allotment of shots for the week and he doesn't expect supplies to be disrupted.

This is a developing story and will be updatd througout the storm.

GBH News reporters Adam Reilly and Mike Deehan and the Associated Press contributed reporting.