What is 'lake effect'? Snow storm science, explained

NOAA satellite image taken Nov. 19, 2014 at 12:45 a.m. EST. (AP / WEATHER UNDERGROUND)

A lake-effect storm that dumped more than a metre of snow in the Buffalo area trapped people on highways in an area where heavy snow is the norm for most of the winter. Up to another metre more is forecast to fall Thursday. Why was this storm so fierce? Some stories from the storm and tips on how to deal if you're caught in the next one:

ABOUT THE LAKE EFFECT

The images were striking: a city awash in daylight, about to be overcome by a thick bank of snow rolling off Lake Erie. Lake-effect snow happens every year around the Great Lakes, so why was this bout in Buffalo so severe?

It's about timing and temperatures, said Patrick Burke, a meteorologist with the National Weather Service's Weather Prediction Center in College Park, Maryland.

Typically, convection draws moisture into the lower atmosphere as cold air moves across a relatively warmer lake, and winds carry the system ashore. This time the air was especially cold, Lake Erie is warmer than it would be later in the year, and the winds stretched the length of the 240-mile-long lake in the right direction, making for an even stronger snow dump that hit land and persisted for an unusually long period, about 30 hours.

"In this case, all of those factors have been maximized," Burke said.

The good news? Though another round of lake-effect snow was forecast into Thursday, he said, the worst of it has passed.

WELCOME TO THE WORLD

Bethany Hojnacki went into labor around 7:30 a.m. Tuesday at the height of the storm. Getting to a nearby hospital was impossible.

So her husband enlisted firefighters aiding a stuck motorist, who turned out to be a maternity nurse at the hospital, The Buffalo News reported. The nurse remained with Hojnacki for hours until a fire department vehicle arrived to take her to the hospital.

When that vehicle got stuck, firefighters took the woman to their firehouse, where baby Lucy was born around 9:30 p.m. Tuesday, weighing in at 6 pounds and 2 ounces. Mother and baby were later taken to the hospital in an ambulance.

A TEAM TRAPPED

Heavy snow stranded many motorists the New York Thruway. Among them: the Niagara University women's basketball team. The team was coming back late Monday night from Pittsburgh when the squad was marooned for nearly 30 hours.

Players ran low on food and even melted snow for water, but local officials dropped off snacks and drinks. There were 25 players and coaches aboard the bus as well as coach Kendra Faustin's 1-year-old son.

The players' kept their spirits up. They posted selfies from the bus, watched movies and caught the Duke-Michigan State men's basketball game on television Tuesday night. Other motorists came aboard the bus seeking shelter and bonded with the team.

"There's been no complaining at all. They've been joking around: I want a steak, I want a soft taco, a Slurpee," Faustin said. "There's definitely nothing in the coaching handbook to prepare you for this."

State troopers eventually picked them up and brought them to a nearby police station where another bus was waiting.

NOT THE FIRST TIME

There have been other examples in recent years of motorists being stranded on highways during snowstorms.

In 2010, hundreds of motorists were stranded along the same stretch of the Thruway when a tractor-trailer jackknifed and backed up traffic. Some motorists spent 20 hours in their vehicles. In 2009, near the same area, more than 100 people spent the night snowbound in cars and trucks on the Thruway near the Pennsylvania border.

In 2011, a fierce snowstorm trapped about and 1,000 vehicles on Chicago's iconic Lake Shore Drive, stranding hundreds of people for as long as 12 hours. By the time the sun came up, three lanes of cars cluttered the road with snow reaching as high as the windshields.

In 2010 in Ontario, a snow-swept Highway 402 near the Michigan border at one point played host to more than 300 stranded motorists. Officials said as many as a dozen of those trapped were airlifted to safety by military helicopters, but there were no reports of deaths or injuries during a long, frigid night.

HELP! I'M STUCK. WHAT DO I DO?

What do you do if you find yourself stuck in the snow?

Pull off the highway and make your vehicle visible to rescuers by turning on hazard lights and tying a bright cloth to your antenna or door handle.

Call 911, if you can, and describe your location. Stay in your vehicle and stay calm. Keep fresh air in your vehicle and the exhaust pipe free of snow to avoid carbon monoxide poisoning. Run the engine at 10-minute intervals for heat and keep a downwind window cracked.

If you have passengers, one person should be awake at all times to look for rescue crews.