Experts expect Great Lakes water levels to stay near or above average

By: Kevin Bunch | Roseville - Eastpointe Eastsider | Published December 2, 2015


Water levels in most of the Great Lakes are expected to stay at or above the long-term average over the next six months, according to the National Oceanic and Atmospheric Administration and the Army Corps of Engineers.

Water levels have rebounded after more than a decade of being at near-record lows the past two years, according to NOAA Great Lakes Environmental Research Lab hydrologist Drew Gronewald. With the exception of Lake Ontario, they are all currently seasonally above the long-term average. That average was compiled using data from 1918 through 2014.

Lake Michigan and Lake Huron — evaluated as one lake due to their connection at the Straits of Mackinac — were about half a foot higher than average, while Lake Erie and Lake St. Clair were both close to a full foot higher than average. Lake Superior was a few inches above its average.

“Monthly or seasonal water levels follow a predictable pattern: they rise in the spring, peak in summer and drop in fall,” Gronewald said. “Going forward, the question is, ‘To what extent do we expect them to depart from that seasonal cycle in the next few months?’”

Complicating matters is the El Niño event in the Pacific, where warm water reaches the surface of the ocean and impacts climate patterns worldwide for several months. Jim Noel, NOAA hydrologist with the National Weather Service, said the strength of the El Niño event puts it at one of the stronger ones on record, which should cause the Great Lakes region to be drier and warmer on the whole than usual.

“This does not preclude shorter periods of cold winter weather,” Noel said. “This means we’ll have winter still, but a repeat of the very cold winter, like the last two, is fairly low because of El Niño.”

Less precipitation than usual in the winter and spring months also means that the water getting into the lakes through over-water rain and snow, and land runoff, could be reduced, he added.

Army Corps of Engineers Detroit Division Hydrology Chief Keith Kompoltowicz said that on the flip side, warmer air temperatures in these fall months have reduced the amount of water evaporating from the Great Lakes, which speeds up as the air gets colder than the water. This in turn means there should be less of a seasonal drop in water levels in the winter months.

Looking past that point, Kompoltowicz said, requires looking to the past. Similarly strong El Niño events in 1982-83 and 1997-98 saw water levels react in completely opposite ways; in the 1980s, levels rose significantly for a few years, while following the 1997 event, lake levels dropped to new lows until around 2013. As a result, even though El Niño is a big factor, it is not the only one that can drive water level amounts.

“This shows a lot more in play here, and it’s impossible to pin what to expect on the Great Lakes to one climate signal,” Kompoltowicz said. “Yes, El Niño gives us some idea of what to expect, but it’s not the only signal out there.”

NOAA climate forecaster Matthew Rosencrans said that there are climate oscillations in the Arctic and North Atlantic that also play a factor every year, and that El Niño’s interactions with them make it hard to predict how the lakes will react in the short term.

Kompoltowicz did say that typically after an El Niño event, there is a greater amount of evaporation the following fall, as weather patterns fall back into their typical routine, and coupled with a drier winter and spring, this could lead to a drop in water levels.

He reiterated that climate researchers just do not know how things will end up at this point, not only for late next year, but for the following several years. Long-term climate modeling suggests that despite global warming, the Great Lakes will continue to oscillate between their already-reached record high and low levels for the coming decades, Kompoltowicz said.