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Volume 10 Issue 8 Nov 2021
Great Lakes Ice Outlook for Winter 2021-2022
Benjamin Baucco, Meteorologist

Ice typically begins to form in the Great Lakes in late December to early January, with the peak ice coverage in late February. Factors that affect the onset of ice formation include water temperature, the position of the polar jet stream (which regulates air temperature), and the ENSO cycle (La Niña/El Niño).

We are currently in the La Niña phase of the ENSO Cycle, which is expected to persist through the winter season for the Great Lakes. La Niña typically yields average to slightly colder temperatures and more snowfall to the Great Lakes regions during the winter, however it has been a very slow start to the winter season so far, which is offsetting this effect. The air temperature across the Great Lakes has been above average, which has resulted in water temperatures significantly above normal (+1°-3°C in most areas).

Sea Surface Temperature Anomaly (°C), as of November 17, 2021.  httpss://

The official seasonal temperature outlook from CPC indicates a 33-40% chance of above normal temperatures across much of the Great Lakes region throughout the winter, and while this forecast generally agrees with climate models for December, the climate models display a signal for colder than average temperatures for January and February (which is more consistent with La Niña).

We are expecting a two-week period of below normal temperatures for the end of November into early December, however this will be followed by a similar duration of above normal temperatures, and is not expected to result in any early onset ice formation.

CPC Seasonal Temperature Outlook for Dec 2021, Jan/Feb 2022. httpss://

Considering the current trend of warmer waters and expected milder temperatures into December, WRI predicts a late onset of ice cover for the entire region with no areas experiencing any significant ice cover by the end of December. With temperatures expected to be closer normal or slightly below normal during January, we anticipate ice formation onset during the first two weeks of January in the narrows of the St. Lawrence River, Georgian Bay, western lake Erie, Saginaw Bay, areas surrounding North Channel/Sault Ste. Marie, Green Bay, Thunder Bay, and the shallows of far western Lake Superior.

Looking further into the winter season, long range analysis has been consistently indicating a cold “blocking” type pattern in place, particularly affecting the eastern lakes by February, which would translate to below normal temperatures and above normal snowfall for much of the northeastern U.S. This type of pattern would be expected to accelerate ice formation in Lake Erie and eastern Lake Huron by late January and throughout February, though would probably not have as much of a cooling effect on the western Great Lakes.

CFSv2 Climate Model Forecast 500mb Height Anomaly for Feb. 2022 indicating a strong signal for a blocking pattern over the eastern U.S.

While during a typical winter this would result in overall above normal ice coverage across the eastern Lakes, the late onset of ice formation is expected to result in near-average ice conditions by the end of February. With more dominant ridging and generally milder temperatures indicated for the western lakes, WRI is predicting an overall below-normal ice forecast for the western Great Lakes this winter.

Baltic Sea Ice Outlook for Winter 2021-2022
Brandon Capasso, Director of Maritime Operations

Ice formation in the Baltic Sea typically begins in November, but only over the far northern portions of the basin within the shallow bays near the shore. As the winter progresses, further ice formation is heavily dependent extent of cold temperatures, which can vary significantly from year-to-year. To further complicate this matter, scientific studies indicate a clear trend of warmer temperatures and decreasing sea ice extent over the Baltic Sea over the past 100 years, which has been notably accelerating over the past 10-20 years. This observation holds true to the notion that climate change certainly affects some parts of the world far more than others.

The ice extent during the 2020-2021 winter season was below average at a maximum coverage of 127,000 km2. Much of the central Gulf of Bothnia and southern Baltic Sea remained ice free for the entire season, which has been the case for most seasons dating back to 2012-2013 (with the exception of 2017-2018).  During the winter of 2012-2013 the maximum ice coverage was 177,000 km2, which is considered average, and the onset of ice formation was considered to be late.

Baltic Sea maximum ice extent during winter of 2020-2021. Finnish Meteorological Institute

When comparing sea surface temperature anomalies between now and this time last year, we note that water temperatures were notably warmer last year, with most areas between 2°-3°C above normal on November 16th, 2020 (right panel). While temperatures are still above normal this year (left panel) the anomalies are generally 1°C cooler than last year.

Sea surface temperature anomaly (°C) on November 16th, 2021 (left), and on November 16th, 2020 (right). httpss://

Looking ahead, there are strong indications that temperatures will be well above normal during the month of December, with climate models predicting a significant 500mb height anomaly centered over Germany and extending northward across much of Scandinavia. This indicates a tendency for the polar jet to remain oriented from Iceland east-northeastward to north of Norway, allowing milder air to flow from the southwest across the Baltic Sea.

CFSv2 forecast mean 500mb anomaly for December 2021.

As the winter continues, there are strong indications of a dramatic shift to a below normal temperature pattern during January and February, and possibly well below normal. This would translate to above normal precipitation (snowfall) during late December/early January, and accelerating ice formation from January through much of February, peaking between late February and early March.

CFSv2 forecast mean 500mb anomaly for January 2022 (left) and February 20200 (right).

While it is difficult to predict the maximum ice extent at this stage, considering the delayed/minimal formation expected during December, followed by two months of above average ice development, it would be reasonable to expect near average ice extent (175,000 km2), with the southern Gulf of Bothnia and southern Baltic Sea remaining ice free for much of the winter, and potentially developing more extensive ice coverage during mid-late February and early March, not unlike the winter of 2012-2013.


Bohai Sea Ice Outlook for Winter 2021-2022
Christine DiGiovanna, Meteorologist

Ice in the Bohai Sea can be extremely variable from year-to-year, with some seasons experiencing very little ice coverage (limited to coastal bays/inlets) and other years experiencing extensive ice coverage across a significant portion of the Bohai Sea.

Sea ice typically begins to develop first in the northern portions of Liaodong Bay during late December/early January (Jinzhou, Bayuquan, and Panjin), with more rapid development throughout January in theses areas and along the western and southern coastal areas of the Bohai Sea, including Huanghua, Tianjin/Caofeidian, Jingtang, and Shanhaiguan.

Sea ice extent in the Bohai Sea on various dates throughout the 2021 winter season.

As shown in the above diagram, the 2021 winter ice season was rather short and below normal, due primarily to a late start and minimal duration of cold temperatures. Another contributing factor was above normal water temperature to start the season, which is shown in comparison to the current water temperature in the figure below.

Bohai Sea SST Anomaly, November 16, 2020 (left) and Nov 16th, 2021 (right). httpss://

The above plot shows that water temperatures were 1.5°-3.0°C higher than normal across nearly the entire Bohai Sea by mid-late November last season, with a majority of the Bohai Sea at or below normal at the same time this season. Countering this factor is the expectation for moderate (slightly above average) temperatures during December, which will likely balance out to a near normal onset of ice formation in late December or early January.

Long range outlook for winter temperatures does not display a strong signal in either the warm or cold direction, and instead indicates near normal or slightly above normal temperature conditions across eastern Asia this winter.

CFSv2 Forecast 500mb Height Anomaly across eastern Asia for Jan (left) and Feb (right) 2022.

Considering the above, we anticipate sea ice conditions in the Bohai Sea to be near normal or slightly below normal this season, with peak ice conditions during mid-late January and receding fairly quickly during late February and March, similar to the 2020-2021 season.

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Webinar: Seasonal Ice Outlook - December 07 2021
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