A blizzard warning is in effect for all of Long Island starting Friday morning into Saturday afternoon, with at least a foot to 15 inches of snow expected to fall -- and perhaps more in some spots, according to the National Weather Service.
State officials urge commuters to be home Friday before the normal evening rush hour, and said shoreline residents should seek alternate shelter to avoid the teeth of the storm.
The storm could bring winds up to 60 mph, down trees and knock out power, said Jerry Hauer, director of the state Division of Homeland Security and Emergency Services.
"If you do have to go to work, plan for an early departure before the storm really gets going and we start getting three to four inches [of snow] per hour and it really gets dangerous," Hauer said at a news conference. "There's going to be a lot of blowing snow and very strong winds that will make travel Friday night into Saturday morning almost impossible."
The warning "means severe winter weather conditions are expected or occurring," the weather service said. "Falling and blowing snow with strong winds and poor visibilities are likely. This will lead to whiteout conditions . . . making travel extremely dangerous."
The North Shore could get a slightly bigger snow impact than the South Shore, as it's a little farther from the ocean and at a slightly higher elevation, said Bill Korbel, News 12 Long Island meteorologist. But that's based on information as of late Thursday afternoon, and conditions could change, he said.
Strong winds, not just snow, will be a problem, he said, "and you know what 50- to 60-mph winds do to power lines and tree limbs. It's one thing to lose power if it's warm out. It's totally another thing when it's below freezing."
Falling on Long Island for much of Friday will be "rain or something frozen -- snow or sleet," he said. By about 6 p.m., temperatures are expected to drop enough to result in heavy snow, he said.
The upgrade to a blizzard warning came as models were indicating colder temperatures and increased snowfall, said Joe Pollina, weather service meteorologist in Upton.
The heavy snow is expected to turn to light snow by about 7 a.m. Saturday, with possible lingering snow showers in the late morning and early afternoon, Pollina said.
The storm surge is expected to be 3 to 5 feet above high tide on the Long Island Sound and 2 to 4 feet on the south shore, said meteorologist Adrienne Leptich at the National Weather Service.
"If you live right on the water, the tidal surge is going to be higher than normal, with three to five feet of strong wave action," Hauer said. "We'd like you to plan on an alternate residence."
Hauer emphasized that shoreline flooding "is not going to be close to what we saw under Sandy," noting the October storm brought a 13- to 14-foot surge.
"But there is some possibility for some flooding along the beaches, along the shoreline," he said.
On the heels of the Long Island Power Authority's superstorm Sandy struggles, LIPA is giving contractor National Grid the "commanding" role in managing its response to the coming winter storm, the utility said Thursday.
In a statement, National Grid said the storm could cause more than 100,000 outages on Long Island, and said it was securing "hundreds" of extra workers to support the 500 linemen, 150 tree trimers and others already on site to respond to the storm.
It is also preparing restoration equipment and pre-stocking material such as transformers in wire around the Island.
It advised customers to take precautions in case of an outage, including securing batteries for radios and flashlights, filling water containers and getting first aid kits. The company said it expects that most outages will be restored within 24 hours, but "some could extend beyond that time."
Customers who experience an outage should call 800-490-0075.
Thursday night, drivers -- apparently fearful of a gas shortage similar to the one that took place in the wake of Sandy -- were lining up at gas stations to fill up their tanks. The lines at some stations were 20-cars long, especially on the North Shore.
Metropolitan Transportation Authority interim director Tom Prendergast said the commuter lines will issue updates Friday on when workers should leave, depending on the snowfall: "We certainly would like people to be home well before the afternoon rush hour. This is a very serious storm and we should treat it that way."
The Long Island Rail Road is "preparing for the worst" and will be prepared to temporarily suspend all service if the looming storm drops more than 10 inches of snow on the tracks, the agency's president said Thursday.
LIRR President Helena Williams said her staff is closely monitoring forecasts and will be ready with extra personnel and equipment in the event of a major snowstorm. That includes special trains that coat the electrified third rail with antifreeze and locomotives stationed at key locations to rescue stranded trains.
To handle "wintry conditions" at area airports, tunnels and bridges, the Port Authority is deploying added staff and readying "snow-fighting equipment," such as airport snow melters and trucks with plows, as well as sand and liquid anti-icer chemicals, according to a news release.
Speed restrictions may be imposed depending on weather conditions, the release said, and travelers should confirm departure times before heading to the airport.
In anticipation of snow accumulations, some of the busiest airlines that fly into and out of New York City have begun offering customers the opportunity to change their travel plans without a cash penalty.
Airlines including Southwest, the major carrier at Long Island MacArthur Airport in Ronkonkoma, and US Airways, JetBlue, American and Delta have all posted notices on their websites about change-fee waivers.
Customers who plans to travel between Thursday and Saturday can make new travel arrangements without being charged a change fee. The window for the rescheduled travel varies by airlines, so customers should check with their airlines.
Officials haven't suspended public transportation yet, but advised commuters to monitor the situation. The state has stockpiled thousands of pieces of snow and ice equipment and has more than 1,000 employees ready to deploy.
A winter storm watch was upgraded to a blizzard watch in Suffolk -- and later a warning for all of Long Island -- because of anticipated sustained winds of 35 mph and visibility of less than a quarter mile with falling and blowing snow for at least three consecutive hours, National Weather Service meteorologist Tim Morrin said.
Morrin said the system coming our way is reminiscent of "every major nor'easter that's caused upward to a foot of snow," citing the 2010 day-after-Christmas blizzard, as well as the storm of Feb. 6, 1978, that just marked its 35th anniversary.