OUTLOOK FOR BREAK-UP OF ICE ON THE ST.LAWRENCE SEAWAY & LAKE ERIE ISSUED BY THE CANADIAN ICE SERVICE

Issued by Canadian Ice Service of Environment and Climate Change Canada

Prepared for The Saint-Lawrence Seaway Management Corporation 2 February 2021

CURRENT CONDITIONS Average temperatures over Lake Erie, Lake Ontario, and the Seaway have been well above normal values consistently since the start of the ice season in early November until near the end of January. At the end of January, temperatures were near to below normal. The highest temperature anomalies occurred in the second half of December and first half of January. The table below indicates the departure from normal temperatures at specific locations, on a bi- weekly basis, for the period from mid-November to the end of January:

November December January 16 Nov. – 16-30 31 Jan 01-15 16-31 01-15 16-31

Montreal +2.0 ºC +4.0ºC +4.1ºC +6.8ºC +0.9ºC +3.6ºC

Kingston +2.8ºC +2.3ºC +3.2ºC +5.4ºC +1.0ºC +2.9ºC

Windsor +1.5ºC +1.3ºC +2.0ºC +4.3ºC +1.4ºC +2.2ºC

Table 1: Departure from normal temperatures With the warm conditions experienced through November across the southern Great Lakes (Erie and Ontario), no ice formed in November. The first ice was recorded on December 16th in the Bay of Quinte and in sheltered bays in eastern Lake Ontario, which was a week earlier than normal. In Lake Erie, the first ice was seen a week and a half later, on December 26th, in line with climatology.

Chart 1: Season ice coverage Lake Erie

Chart 2: Season ice coverage Lake Ontario Due to the continued above normal temperatures through December and January, some ice did continue to form in the western basin of Lake Erie, however, the ice was easily destroyed as low pressure systems moved through. Ice conditions remained well below normal through most of January before normal to below normal temperatures return at the end of January and ice started to grow. The ice in Lake Ontario was slightly more robust, residing in protected bay, but ice was still slow to form, remaining relatively unchanged since first forming in mid-December. Much like in Lake Erie, temperatures dropped at the end of January and ice expanded in the eastern portions of the lake. Ice in the seaway first formed in mid-December with some new and thin ice. Ice growth became stagnate shortly after the first formation, with only slight changes between periods of ice growth and ice melt. As was the case for the southern lakes, towards the end of January ice did grow more substantially with the colder temperatures. The table below indicates the monthly average temperatures at three locations along the Seaway and in western Lake Erie.

Average temperatures

December 2020 January 2021

Montreal -2.1ºC -6.5ºC

Kingston -0.8ºC -4.5ºC

Windsor +0.4ºC -1.6ºC

The table below indicates the accumulated freezing degree days (FDD), the normal accumulated FDD and the percentage (%) of accumulated FDDs at various locations as of January 31, 2021.

Accumulated Normal % of normal accumulated FDD accumulated FDD FDDs (2020-20)

Montreal 289 557 52%

Kingston 190 389 49%

Windsor 83 224 37%

Ice conditions in the St Lawrence Seaway are described based on Radarsat Constellation Mission (RCM) and Sentinel-2 images from January 29 to February 2, 2021. From Kingston through to Cornwall, new and thin ice mainly lines the shore of the seaway with lesser concentrations found in the main channel. From Cornwall to the Beauharnois Canal, the seaway is completely ice covered with mainly thin ice. Within the Beauharnois Canal, there are some stretches that are open water, but most of the central section is completely ice covered. East of the canal to Montreal and the St. Lambert lock, the seaway is mainly ice covered with thin ice, while some short segments of the main channel are still open water. Most of this ice has formed in the last week of January due to the near to below normal temperatures we have experienced across the region.

GENERAL OUTLOOK

Average surface air temperatures will be above normal for the next few days before near to below normal air temperatures will return for the rest of February. For March and April temperatures are forecast to remain near normal to slightly above normal through the southern Great Lakes and the Seaway. Due to the recent ice formation and expected near to below normal temperatures for February, ice is expected to remain and thicken through the month.

Lake Ontario to Cornwall – The ice that already lines the shores will continue to thicken. Ice will also continue to expand through February into the main channel of the seaway. With near to slightly above normal temperatures expected through March, no substantial thickening is expected and the ice will begin to break up in mid-March. Open water conditions are expected by early-April.

Cornwall to Montreal – The area is expected to remain ice covered and thicken through February before break-up is forecast for mid-March. Predominantly open water conditions are forecast by early-April.

Lake Erie – Ice cover will rise, especially in the western Basin of Lake Erie during the month of February and peaking by late-February. With above normal temperatures forecast for March, break-up and melt is expected to occur through March with predominantly open water conditions expected by the end of March.

Contact: Canadian Ice Service Email: [email protected]