CANADA: INTENSE WATER SURPLUS TO PERSIST IN SOUTHERN BC

17 May 2018

THE BIG PICTURE
The 12-month outlook for Canada through January 2019 (below) indicates water deficits of varying intensity in many parts of the country, with the exception of southeastern British Columbia and the northern border shared by Alberta and Saskatchewan, where intense surpluses are expected.

Deficits are forecast to be intense in: a large block of eastern Quebec from the Caniapiscau Reservoir to the St. Lawrence River, and around Lake Mistassini in central Quebec; Ontario’s eastern border; and northeastern Manitoba, north of Lake Winnipeg, and southern Manitoba. In the West, significant deficits are forecast for central Alberta north and west of Edmonton, northwestern Alberta, a large pocket in British Columbia surrounding Prince George, and northern BC.

Surplus conditions are expected in a large block of northwestern Saskatchewan around Churchill Lake westward to Fort McMurray, Alberta; and surrounding Kamloops and Kelowna, BC.

FORECAST BREAKDOWN
The 3-month maps (below) show the evolving conditions in more detail.

Two noticeable transitions stand out in the near-term forecast through July: a change from surplus to deficit in northern Quebec, and the widespread emergence of exceptional surplus in southeastern British Columbia. Though deficits are forecast for much of Quebec, southeastern Quebec near the mouth of the St. Lawrence River is expected to transition from deficit to exceptional surplus. Deficits in Ontario will diminish considerably but will persist along the eastern border with exceptional intensity. Exceptional deficits will increase in northeastern Manitoba on Hudson Bay and in a large pocket north of Lake Winnipeg; deficits in the south will be severe.

Moving west, exceptional surplus conditions will increase from Churchill Lake, Saskatchewan to Fort McMurray, Alberta. Deficits of varying intensity are forecast for the remainder of Saskatchewan and large pockets of intense deficits are expected in Alberta north and west of Edmonton, and also in the far northwest corner of the province. Moderate to severe surpluses will emerge in southern Alberta along the South Saskatchewan River. In British Columbia, as previously mentioned, a large block of exceptional surplus is forecast in the southeast surrounding Kelowna and leading north well past Kamloops. Surpluses are also forecast in northeastern BC around Fort St. John; large pockets of severe to exceptional deficits are expected surrounding Prince George and in the northwest.

From August through October, surpluses are forecast in easternmost Labrador and directly south in easternmost Quebec. Deficits will shrink overall in Quebec but deficits of varying severity are forecast stretching from west of Lake Mistassini eastward into Labrador, and may be intense around the Caniapiscau Reservoir. Aforementioned anomalies elsewhere across the country will diminish. Some intense deficits will persist in northeastern Manitoba around Hudson Bay, deficits of varying severity will persist in northern BC, and surpluses in northern Saskatchewan and southern BC will begin to transition to both surplus and deficit.

The forecast for the final three months – November through January – indicates a significant downgrade in anomalies nationwide.

(It should be noted that forecast skill declines with longer lead times.)

IMPACTS
The eastern province of New Brunswick experienced historic flooding on the St. John River when regional snowpack melted in a late April warm spell. Over 1,500 residents were forced from their homes, and many riverside and lakeside cottages were submerged, damaged, or swept away entirely. The flooding is reported to be one of the worst spring floods since 1973 and cleanup operations are expected to last several weeks, with health officials warning of bacterial and chemical contamination.

April temperatures reaching as high as 30 degrees Celsius (86 degrees Fahrenheit) and two days of rain in May rapidly melted enough of this year’s large snowpack to cause flooding in several areas of the British Columbia interior, evacuating occupants of roughly 3,000 homes this month. In some areas the flooding was the worst seen since 1948.

Overland flood insurance is expanding in Canada, and one Canadian insurance company has become the first and only to offer storm surge coverage in the high-risk areas of coastal Nova Scotia and British Columbia. The company's leader cites overland flooding as the most pervasive and costliest cause of damage to Canadian homes. A 2017 survey conducted by a research network to advance flood resiliency indicated that almost all Canadians living in high-risk areas are unaware of their flood risk.

A dry spring on the heels of a dry winter is worsening a moderate-to-severe drought in southern Manitoba, southern Saskatchewan, and parts of Ontario. Dry conditions have encouraged early-season grass fires that destroyed a number of homes in southern Manitoba in late April, prompting burn bans in many cities. The Saskatchewan government likewise banned open fires indefinitely in several places south of the Churchill River.

NOTE ON ADMINISTRATIVE BOUNDARIES
There are numerous regions around the world where country borders are contested. ISciences depicts country boundaries on these maps solely to provide some geographic context. The boundaries are nominal, not legal, descriptions of each entity. The use of these boundaries does not imply any judgement on the legal status of any territory, or any endorsement or acceptance of disputed boundaries on the part of ISciences or our data providers.

Subscribe to our monthly Water Watch List

Search blog categories

Search blog tags