Spring 2023 eNewsletter

Understanding the Changing Patterns of Great Lakes Ice Cover and Winter Weather

Ice cover is an important part of the experience of coastal communities in the Great Lakes, from being an obstacle to vessel navigation to providing an opportunity for winter recreation. Ice plays a key role not only in regional weather, but also in environmental quality and economic prosperity. This year, ice coverage on the Great Lakes was at a near record low, and the impacts were felt across the region.

MODIS satellite image of the Great Lakes, February 13, 2023. The lakes were only 7% ice covered on this date, which is significantly below the 35-40% ice cover that is expected for this time of year. Photo Credit: NOAA GLERL.

“Warmer lake surface temperatures and low ice coverage in the Great Lakes can trigger severe lake-effect snowstorms, such as the December 2022 severe lake-effect snowstorm that gripped the majority of the Great Lakes region and included 41 deaths in Buffalo, New York,” said CIGLR Assistant Research Scientist, Ayumi Fujisaki-Manome. Ayumi leads CIGLR’s ice and snow research program that aims to improve the predictability of hazardous weather, ice, and lake/ocean events to support preparedness and resilience in coastal communities. “Typically a lake-effect snow season ends by early-to-mid February, as ice covers the surface of the lakes. However, with less ice, more late-season lake-effect snowfalls can be anticipated, such as the late March [2023] lake-effect snow event that impacted west Michigan, leaving 18 inches of snow in just a few days. Larger open water areas during the windy winter season also pose concern of high waves, which can damage shoreline when it loses protection of stable ice cover along the coast.”    

Air temperature is a main factor affecting ice cover on the Great Lake. Alarmingly, warmer than average temperatures were recorded this winter, especially in the month of January. A recent study by NOAA’s Great Lakes Environmental Research Laboratory (NOAA GLERL) reports that Great Lakes ice coverage is on a downward trend, showing a 70% decline in the lakes’ ice cover between 1973 and 2017. To many people, this seems like quite a different story from the recent 2019 winter. “In January 2019, a cold blast that closed schools, state offices, and other businesses is clearly remembered as one of the coldest, most extreme, ice-covered winters in recent years,” says Fujisaki-Manome.

So, what’s the story behind this variable ice coverage and winter weather?

“The year-to-year fluctuations of Great Lakes ice coverage became larger in the past two decades,” said Fujisaki-Manome. “Long-term patterns of climate variability over the Pacific and Atlantic Oceans are key factors that are contributing to the reduction of ice. There was an interesting shift in the patterns during the winter of 1997/1998. Before this shift, the Great Lakes annual maximum ice cover significantly correlated with a couple of well-known climate indices, the El Nino–Southern Oscillation and North Atlantic Oscillation. However, after this shift, these climate indices no longer presented significant correlations with the Great Lakes annual maximum ice cover. Instead, the Eastern Pacific Oscillation and the sea surface temperature anomaly over the North Pacific presented significant correlations.”

Dr. Fujisaki-Manome looks for process-based evidence that supports the relationship between Great lakes winter severity and the sea surface temperature anomaly over the North Pacific.

“So far we have found that notable wave energy emanating from the warm sea surface temperature in the North Pacific contributes to the meandering of the jet stream, which can ultimately contribute to the Great Lakes winter severity and warming,” said Fujisaki-Manome. “In addition to the ice cover, we are also investigating changes in winter storm tracks, storm intensity, and frequencies.”

Dr. Fujisaki-Manome and her team are focused on understanding what large-scale atmospheric circulations and patterns control the Great Lakes regional climate variability and extreme weather event occurrences.

“Year-to-year fluctuations of ice cover and winter severity are expected to remain high (if not increase further) and extreme weather events can be anticipated, such as the historic ice storm that struck southeast Michigan in late February 2023,” said Fujisaki-Manome. “It’s so important to understand these changes, how they can be attributed to climate variability and warming, and ultimately be able to make better predictions from our continued data collections and observations.”

Dr. Ayumi Fujisaki-Manome aims to improve predictability of hazardous weather, ice, and lake/ocean events in cold regions in order to support preparedness and resilience in coastal communities. Her research questions address the impacts of interactions between ice and oceans /ice and lakes on larger scale phenomena, such as weather, storm surges, and sea/lake ice melting. Dr. Fujisaki-Manome primarily uses numerical geophysical modeling to address her research questions. Then, scientific findings from her research feed back into the models and improve their predictability. Her work is applicable to the Great Lakes, the Arctic Ocean, the Alaskan coastal region, and the Sea of Okhotsk.

Related Articles & Resources:

• Lin, Y., A. Fujisaki-Manome and J. Wang. 2022. Recently Amplified Interannual Variability of the Great Lakes Ice Cover in Response to Changing Teleconnections. Journal of Climate. 35(19): 2683-2700. (DOI:1175/JCLI-D-21-0448.1).
• Wang, J., J. Kessler, F. Hang, H. Hu, A.H. Clites and P. Chu. 2017. Great Lakes Ice Climatology Update of Winters 2012-2017: Seasonal Cycle, Interannual Variability, Decadal Variability, and Trend for the period 1973-2017. NOAA Technical Memorandum GLERL-170.