Seasonal Outlook for North American Arctic Waters - Summer 2011

Freeze-up and Winter Ice Regime

Air temperatures averaged 2 to 4°C above normal throughout September and October, 6 to 8°C above normal in November and 12 to 16°C above normal from early December through to the third week of January. All ice cleared out of Foxe Basin in the first week of September, 2 to 3 weeks earlier than normal, and the entire region was ice-free by mid-September breaking the record for the lowest seasonal average ice coverage. Freeze-up was delayed in all areas with initial ice formation taking place during the first week of November along the shore of Foxe Basin, Southampton Island and along the western shore of Hudson Bay. Ice development was confined to these areas until mid-December due to the mild temperatures and strong winds associated with a continuous stream of low pressure systems moving through Hudson Bay, Foxe Basin and / or moving northward along the Labrador Coast into Baffin Bay. Therefore, the ice extent into all areas was slow to develop and was delayed by 6 weeks in Hudson Bay such that it was mid-January before it was ice covered. The ice migration and development eastward through Hudson Strait was delayed by as much as 8 weeks and only became ice covered during the last week of January. Ice formation in Frobisher Bay and along the Labrador Coast was also delayed by 8 weeks with new ice developing in the inner bays during the first week of January while new ice still predominated over the Labrador Coast by the end of January. Low ice coverage records were broken for all areas especially in Hudson Strait, Davis Strait, and the northern Labrador Sea where only 36% of normal ice coverage had developed by early January, becoming near normal coverage with new ice development for most areas by the end of January. The northern Labrador Sea, however, maintained record low amounts of ice coverage. The calculated theoretical ice thicknesses were much less than normal in all areas by the end of January.

By the third week of November new and grey ice with fast ice in sheltered bays had become established along the southwestern shore of Southampton Island and the western shore of Hudson Bay with new ice extending along Hudson Bay and James Bay western shores. In early December, grey ice covered much of Roes Welcome Sound and extended southward along the western shore of Hudson Bay to Churchill with mostly new ice further south along Hudson Bay southwestern shore and James Bay shores. Grey ice was also forming along the eastern Foxe Basin shore and in sheltered bays along the northeastern shore of Southampton Island at this time. Ice continued to spread south and eastward at a slower than normal pace through December with grey and grey-white ice forming southward through Foxe Basin and western Hudson Bay. New ice started to form in southern Ungava Bay and along the northwestern shore of Hudson Strait by the third week in December. By the end of December, most of Foxe Basin and western Hudson Bay was covered with grey and grey-white ice. New and grey ice was becoming established over much of central Hudson Bay as well as western and southern James Bay. A large area of open water, at the end of December was still evident from southern Foxe Channel to central James Bay. The total ice coverage for Hudson Bay and approaches was 15% less than normal at this time setting a new 30 year minimum record.

In early January, grey-white with thin first-year ice pushed southward into Foxe Channel with grey-white ice extending further east into central Hudson Bay and western James Bay. Ice growth was still well behind normal at this time with a large area of open water still remaining in southeastern Hudson Bay. Patchy new with some grey ice started forming in Hudson Strait at this time while Frobisher Bay remained opened with patchy new ice forming in the inner bay near Iqaluit and with a mix of new and grey ice drifting southward into the entrance of Frobisher Bay to Resolution Island. Hudson Bay did not completely freeze over until mid-January with ice thicknesses much less than normal with thin first-year ice predominating along with grey-white ice. Hudson Strait became ice covered during the last week of January with predominantly grey-white ice with thin first-year ice in the western portion and mainly grey and grey-white ice in the eastern entrance and into Ungava Bay. Low ice coverage records were broken for all areas and only 36% of normal ice coverage had developed by early January in Hudson Strait, Davis Strait and the northern Labrador Sea. The ice slowly formed and thickened to grey ice for the majority of Frobisher Bay during the last week of January with a tongue of thin first year ice drifting southward into the entrance of the Bay. Patchy new and grey ice started to form along the northern Labrador coast during the last week of January and thickened to mostly grey and grey-white ice and reached the approaches to Groswater Bay by mid February. The calculated theoretical ice thicknesses were less than normal in all areas with theoretical thicknesses varying from 15 cm thinner than normal in southern Hudson Bay to 30 cm thinner than normal in Foxe Basin, northern Hudson Bay, Hudson Strait, Ungava Bay and along the Labrador Coast. Theoretical ice thicknesses were as much as 44 cm thinner than normal in Frobisher Bay.

Slower than normal ice growth was observed for the second half of February and into the month of March. At the end of February, a mix of thin and medium first-year ice covered most of the central section of Hudson Bay and southern Davis Strait, while mostly thin first-year ice covered the rest of Hudson Bay, Hudson Strait, Frobisher Bay and Cumberland Sound. However a narrow band of grey ice with patchy grey-white ice was predominant along the western shore of Hudson Bay. A trace of multi-year ice was observed in the pack ice over Davis Strait. Along the Labrador Coast, ice concentrations remained slightly less than normal with mostly grey-white ice. As well, the eastern extent of the ice edge was located farther west than normal for the end of February. The ice continued to thicken during the month of March with medium first-year ice covering the eastern section of Hudson Bay, while a mixture of medium and thin first-year ice prevailed over western Hudson Bay, in James Bay, in Hudson Strait and Cumberland Sound. The ice was generally thicker in southern Davis Strait, while the ice was compressed along the Labrador Coast during the month of March with a trace of old ice embedded in the pack ice. A series of deep storms moving across the area during the last two weeks of March has loosened up the pack ice north and east of Belcher Islands, in most of Hudson Strait and along the ice edge over the Labrador Sea. Similar ice conditions continued to prevail during the month of April with medium first-year ice over most of Hudson Bay and Hudson Strait, while thick first-year ice dominated over southern Davis Strait and along the Labrador Coast. However, embedded areas of very open drift multi-year ice drifted southward to reach the extreme northern portion of the Labrador Coast by the end of April. During the second half of April, a large area of grey-white and grey ice developed along the western shore of Hudson Bay and the southern shore of Southampton Island.

During the first half of May, ice conditions persisted in most areas except for the eastern regions. However, the ice started to decay quite significantly over the eastern section of Hudson Strait and along the Labrador Coast where large areas of bergy water were observed resulting in lower than normal ice concentrations. Meanwhile, areas of very open drift multi-year ice were embedded in the pack ice over southern Davis Strait, while a trace of multi-year ice persisted along the Labrador Coast. During the last two weeks of May, large areas of bergy water developed over Frobisher Bay and the northern section of Hudson Strait. Clearing was already underway along the eastern and northwestern shores of Hudson Bay. At the end of May, loose ice conditions were present over southern Davis Strait and along the Labrador Coast.

Observed Ice Conditions

The regional ice chart in figure 3 was based on the analysis of Radarsat 1 and 2 and NOAA/MODIS imagery from around May 23, 2011. This chart revealed some of the following features:

1. Lower than normal ice concentrations and bergy water areas are present along the Labrador Coast, Frobisher Bay, in northern Hudson Strait and in eastern Ungava Bay. This is indicating that the ice breakup is 2 to 3 weeks ahead of normal.
2. A trace amount of multi-year ice is embedded in the pack ice along the Labrador Coast and in the eastern entrance to Hudson Strait, while isolated areas of 2 tenths of multi-year ice are present over western Davis Strait.
3. Areas of open water along the northwestern and eastern shores of Hudson Bay are 1 to 2 weeks ahead of normal.
4. Ice thicknesses over all areas are 15 to 25 cm less than normal for this time of year.

Figure 3: Hudson Bay Regional chart for May 23, 2011

Outlook for Hudson Bay

The summer temperature outlook from June to August suggests above normal temperatures along the Labrador Coast and Hudson Strait and near normal temperatures over the eastern section of Hudson Bay. Over western Hudson Bay, temperatures should remain slightly below normal values for the period. However the presence of multi-year ice over the southern section of Davis Strait and along the Labrador Coast will slightly delay the ice decay but not enough to have an impact on the breakup. Accumulated freezing degree days at mid-May are still well below normal values which will result in an earlier than normal breakup. The trend for the clearing for this summer will be from north to south over Hudson Bay and from west to east across Hudson Strait. As for the Labrador Coast, the ice will continue to retreat northward. However areas of fast ice are still present in bays and inlets along the Labrador Coast and in Lake Melville. The first area to open will be the open water route across northern Hudson Bay where it will occur during the first week of July.

At the end of the first week of July, a bergy water route will develop in Hudson Strait, while the ice will melt completely along the Labrador Coast. By that time, an open or bergy water route will be established from the eastern entrance of Hudson Strait into Churchill. With the ice retreating northward east of Hudson Strait, the ice will loosen up in Frobisher Bay resulting in an open drift or less route to develop over the area during the second week of July. With the clearing occurring from west to east, the last ice to remain will be over eastern Hudson Strait and southern Ungava Bay, where clearing will develop during the third week of July. A week later, the ice will melt completely along the shipping route to Frobisher Bay. The last remaining ice to melt will be located over southern Hudson Bay where it should clear during the third week of August. Breakup events for Hudson Bay and James Bay will be normal due to the clearing pattern that is expected this summer.

Figure 4: Hudson Bay sea ice concentration anomaly outlook for July 2011

Note: Based on Canonical Correlation Analysis (CCA) techniques similar to those used to produce the Canadian Meteorological Centre seasonal temperature outlooks. For details see: Tivy, A., S.E.L. Howell B. Alt, J. Yackel and T.Carrieres (2011) Origins and levels of seasonal forecast skill for sea ice in Hudson Bay using Canonical Correlation Analysis. Journal of Climate, doi:10.1175/2010JCL13527.1.