Canada: Extreme water surpluses to persist near Ottawa

28 November

THE BIG PICTURE
The 12-month outlook for Canada through July 2018 (below) indicates large blocks of exceptional water deficits in eastern Quebec at the mouth of the St. Lawrence River, western Labrador and Newfoundland, New Brunswick, central Quebec, around the eastern and western shores of Hudson Bay, and northwestern Ontario into central Manitoba.

Severe to extreme deficits are forecast for the central Quebec/Ontario border, north-central Saskatchewan, central and northwestern Alberta, and pockets in British Columbia surrounding Prince George, east of Vancouver, and in the far northwest.

Exceptional surpluses are forecast for central Manitoba west of Lake Winnipeg and into Saskatchewan, and in northwestern Saskatchewan around Churchill Lake westward past Ft. McMurray, Alberta.

IMPACTS
Two months shy of the year’s end, 2017 has already earned the title of Ottawa’s wettest year on record. Extreme rainfall at the end of October across the Ottawa-Gatineau metropolitan region in southern Ontario into western Quebec left up to two feet of flooding, disrupting city operations, damaging roads, and creating power outages during a record-breaking storm. In the wake of increasingly frequent extreme precipitation events, which regional mayors describe as the new normal, many communities are recognizing infrastructure needs that their tax bases may not be able to support.

Flooding this year has cost Canada $600 million (US$469 million) in insured damages, prompting a second look at flood insurance coverage and program solvency. The Minister of Public Safety convened a day-long roundtable event recently for authorities and insurance leaders to discuss public education of flood risks and sustainable financial models. The federal government is facing some industry pressure to consider federally subsidized models like the US National Flood Insurance Program or Britain's Flood Re, though industry leaders readily admit that no adequate model currently exists.

The year-long drought in southern Saskatchewan persists, as the cities of Regina and Swift Current experienced the driest year on record between November 2016 and October 2017.

Slow drought from hydroelectric dam development is one of the many threats faced by Canada’s largest national park, a UNESCO World Heritage Site. Wood Buffalo National Park, encompassing 45,000-square kilometers along the Alberta-Northwest Territories boundary, is home to the world’s largest freshwater inland delta, which has experienced plummeting flows in the last three years, endangering the park's World Heritage status.

Further west, the worst wildfire season on record in British Columbia is being blamed on increasingly higher temperatures and drier conditions. Fire displaced 45,000 residents at the season’s peak. Nation-wide, the amount of fire activity has doubled since the 1970s, according to a wildfire expert at the University of Alberta.

A narrow isthmus is all that keeps the peninsula of Nova Scotia from becoming an island, but officials warn that projected sea level rise over the next 20 years threatens to severe the connection to mainland New Brunswick. The primary line of defense remains a system of 275-year-old dikes that protect electricity transmission lines and daily trade flows of $50 million (US$39 million) via road and rail. Local officials hope to secure federal disaster mitigation funds to help fund a multi-million dollar upgrade.

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

While the forecast for Canada remains a patchwork of water anomalies, the most noticeable difference in the near-term forecast – November through January – compared to the prior three months’ observed conditions is the widespread emergence of surplus conditions in Quebec and the downgrade of deficits west of Hudson Bay.

Significant deficits are forecast during this period, however, for many areas, including (east to west): western Labrador and Newfoundland, the mouth of the St. Lawrence River, and the southern portion of the Island of Newfoundland; eastern New Brunswick and Nova Scotia; Jamésie, Nord-du-Québec and the northern border between Quebec and Ontario; the southeast and southwest shores of Hudson Bay; northwestern Ontario into central Manitoba; southern Manitoba and southeastern Saskatchewan; from Calgary, Alberta across the border into British Columbia, and northeast through Slave Lake, Alberta; and, pockets of British Columbia west of Kamloops, surrounding Prince George, and in the northwest.

Surpluses ranging from moderate to exceptional are expected to emerge in much of northeastern Quebec. Primarily moderate surpluses will emerge in southern Quebec but conditions may be extreme near Ottawa. Surpluses will continue to emerge in a vast stretch of central Ontario and are expected to be exceptional north of the middle stretch of the Albany River in Kenora. Exceptional surpluses are forecast west of Lake Winnipeg in Manitoba and into Saskatchewan; in northwest Manitoba; and in a large block surrounding Churchill Lake in Saskatchewan leading west past Ft. McMurray, Alberta, and south along the Beaver River in SK. Surpluses ranging from severe to exceptional are forecast along the central border of Alberta and British Columbia and west past Williston Lake.

From February through April surpluses in Quebec and Ontario will shrink, leaving a large block of surplus in northeast Quebec, near-normal conditions in many parts of eastern Canada, and persistent blocks of intense deficits. Deficits and surpluses in the Prairie Provinces and in the West will moderate somewhat, though the distribution of water anomalies will remain the same.

The forecast for the final three months – May through July – moderate deficits across the north with more intense deficits in northeastern Manitoba.

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

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