The National Football League did something it has not done in almost 10 years. It moved a game from Buffalo, New York because of snow. It was the right call because the area could see snowfall totals measured in multiple feet by Sunday. Even as I write this Friday morning, the region is seeing jaw-dropping amounts of “thundersnow.” Let’s break down the meteorology of what is going on with this lake effect snow machine.
Earlier this morning, the National Weather Service (NWS) in Buffalo tweeted, “Heavy lake effect snow with snowfall rates of 3 inches per hour….The band off Lake Erie will shift slightly north, moving into more of the city of Buffalo.” Some places have already reported around a foot of snow, and it is far from over. Even the NWS Weather Prediction Center (WPC) is calling for a potentially historic storm over the next few days. While some 5 to 6 feet totals have been mentioned, WPC expects 1 to 3 feet of snow but mentions the possibility of around 4 feet in Buffalo. Lake Effect snow will persist through Sunday but Friday will likely be the day with the heaviest snow rates. So what’s going on?
At this time of the year, the Great Lakes are still relatively ice-free. Water tends to stay warm longer than land as we transition to the cold season because of its heat capacity. Under certain conditions, this can produce a prolific snow machine downwind of the lakes. The NWS website notes, “Lake effect snow is common across the Great Lakes region during the late fall and winter.” However, this is an epic setup. Lake Effect snow happens as cold Canadian air moves across the relatively warmer lake waters. The NWS goes on to point out, “….warmth and moisture are transferred into the lowest portion of the atmosphere….air rises, clouds form and grow into narrow band that produces 2 to 3 inches of snow per hour or more.”
The wind direction is very important for the largest potential totals. If the wind fetch is oriented with the longest axis of the lake, there is significant snowfall potential. Because of this orientation, there can be very isolated areas of heavy snowfall and virtually noting a few miles away. The Lake Effect snow machine is also affected by the physical geography and certain atmospheric conditions such as temperature and stability. In the satellite imagery taken Friday morning (below), bands of snow-producing clouds over the lakes illustrate the optimized fetch for snowfall. The greenish-yellow colors are indicative of lightning.
If lightning is present, that causes “thundersnow.” Our newest geosynchronous weather satellites carry a lightning mapper, which enables detection of lightning activity in these types of systems. With this particular system, the instability and moisture are ideal for the production of grapple, according to winter weather expert Tom Niziol on his Facebook page. Dakota Smith’s tweet below places the “thundersnow” activity in perspective, and we have a few days of this to go.