For the first time since the end of last November, there is finally no ice left on the Great Lakes. Goodbye and good riddance to the winter that just wouldn't die. Now that there's no more ice, what does this mean for weather patterns in the northern United States?
The year's lake ice was one for the record books. This was the latest complete melt on the Great Lakes since NOAA started keeping records back in the 1970s. The season also saw the second-highest amount of ice ever recorded, with just over 92% covering the five bodies of water at the beginning of March, coming close to the all-time record 94% coverage seen in 1979. This year also broke the record for the most ice seen so late in the season, with over one-third of the lakes still covered in ice on April 23.
The lack or presence of ice can have a huge impact on the weather, but it depends on the season.
The most obvious effect that lake ice has on the weather is lake-effect snow, which occurs when cold air moves over the warmer waters. The warmer lake water heats up air at the surface through conduction, and the warmer air begins to rapidly rise through the much colder air above.
The result is convection, which sets up as heavy snow bands that move over land. When the lakes freeze over, lake-effect snow stops. This is why areas on the eastern shore of Lake Ontario some of the highest annual snowfall totals in the country; Lake Ontario hardly ever freezes over during the winter.
On the summer side of things, the lakes don't have too much of an impact on the weather.
During the warm months, the lakes can have a cooling effect on areas immediately along the coast depending on the direction of the winds.
On rare occasions, the water can have an effect on storm systems. This was most notable in 1996, when a low pressure system sat over Lake Huron and started to take on characteristics of a subtropical cyclone, lending it the nickname "Hurricane Huron."
One of the most spectacular sights over the Great Lakes are waterspouts that tend to form during the summer and fall months. Waterspouts form when a column of rising air stretches out and begins to rotate; the low pressure inside the rotating column of air condenses the water vapor, leading to the visible condensation funnel.
Waterspouts are different from tornadoes in that tornadoes form from processes within a thunderstorm, whereas waterspouts are usually independent entities. Waterspouts can easily form in thunderstorms, though, due to the ample amount of rising air they require to survive.
Provided we don't have any freaky weather over the next couple of month, the Great Lakes should remain ice-free until sometime around Thanksgiving.
[Images via AP / GLERL / NWS]