Lake-effect snowstorm could dump 40 inches in parts of New York
Residents living east of lakes Erie and Ontario could be in for some severe weather
Imagine getting more than 100 centimetres (40 inches) of snow in under two days. Then picture driving a few towns over and finding they didn’t even have to plow. This is the world of lake-effect snow.
That scenario could unfold late east of Lakes Erie and Ontario. Downwind of Lake Erie, 25 to 50 cm is forecast. East of Lake Ontario, double that — in some locales, more than three feet.
Blizzard warnings are in effect downwind of both lakes. Strong westerly winds gusting up to 96 km/h at times will channel building snow streamers to the lakes’ eastern shores while reducing visibility at times.
The gales could also trigger scattered power outages and sculpt snow drifts up to 2.4 metres high.
Early Thursday, the National Weather Service in Buffalo warned of the “rapid onset of blizzard conditions this morning.”
“Winds will rapidly increase and temperatures will drop through mid to late morning, resulting in the development of severe blowing and drifting snow and near zero visibility,” the weather service wrote.
In Watertown, N.Y., the visibility dropped from 14 km to 800 metres as snow abruptly began. Winds at 9 a.m. were gusting over 64 km/h ; earlier in the morning, they were listed as calm. Blizzard conditions were observed there beginning at 7 a.m. Thursday.
“We’ll have six-hour amounts approaching a foot,” said Jim Mitchell, a meteorologist at the National Weather Service in Buffalo. “Two inches per hour on average, some areas will see three to four inches per hour at times. The heaviest snow will be east of Lake Ontario; the biggest window will be Thursday into early Friday.”
It’s the perfect recipe for a ripping lakeeffect band that produces snow. A few claps of thundersnow are even possible.
“It’s about wind direction,” said Mitchell. “How long is that wind going to stay in the same orientation? Obviously, if the winds shift, the band is going to waver.”
But a stalled low-pressure system to the north will help an ideal wind pattern become established.
It’s late in the season to see such hefty lake-effect snow. In Watertown, for example, the overwhelming majority of its biggest snows historically have occurred before the end of February. But Mother Nature is doing everything in its power to generate a winter wonderland.
Instrumental in the ongoing snow is the lack of ice over Lakes Erie and Ontario. Lake-effect snow can only develop when a lake’s waters are exposed to the atmosphere above it. This year, a significant deficit in ice coverage has allowed lake-effect snow deeper into the season than usual.
“Lake Erie a lot of times shuts off because it freezes, but we usually still get some effects from the lake,” said Mitchell. Among these influences can be frictional convergence, or the development of snow showers enhanced by easier air flow over the smoother lake surface.
“It is well below average,” said Elizabeth Thomas, an assistant professor in the geology department at the University at Buffalo. “It’s low, but it is not unprecedented in this record.” She said ice coverage records date to the early 1970s.
Frank Marsik, an associate research scientist at the University of Michigan, offered numbers on the ice deficit.
“This year, we’re considerably below normal,” he said. “Last year at this time of year, we were looking at about 70 per cent Great Lakes ice coverage. This year, we’re looking at about 10 per cent.”
He noted that 2012 and 2017 also featured below-average ice coverage.
“Most of the lakes are running one to two degrees above where they were last year, and that’s playing a role in ice coverage,” said Marsik. He attributes that to mild temperatures this season.
Thomas said that a warming world in the future could favour more lake-effect precipitation and reduced ice coverage. But not all of what falls will be snow.
“If winters continue to get warmer, we might get more rainfall,” she said. “Though if we continue to get those outbreaks of Arctic air ... we could get some pretty severe lake-effect storms.”
As winds drive water across the lakes, water is piling up along their eastern shores. Lakeshore flood warnings are in effect, the National Weather Service calling for “flooding along the shoreline ... especially in bays and inlets and other low lying shoreline areas.”
This flooding will be heightened by lakewater levels that are running up to a several centimetres above average this year, thanks to recent precipitation. Marsik said 16 of 24 months in 2018 and 2019 had abovenormal precipitation in the southern Great Lakes.
Fluctuating water levels and chaotic swings have proved a headache for coastal residents, some of whom have suffered flooding of their homes or even taken a hit on their property values.
There is even the possibility of several feet on the east ends of Lakes Erie or Ontario through Friday. That occurs when strong winds or a rapid change in air pressure slosh water from one side of the lake to the other.
Water levels could be more than three feet above normal along the eastern shores, while the west end of the lakes may see below normal levels.
A two-metre seiche accompanied strong westerly winds in Buffalo in October. Toledo, on the opposite end of the lake, saw water levels drop by about a metre.