Flooding picture still weather dependent

What happens between now and spring here, and in the U.S. and Saskatchewan, will be the determining factors

Flooding picture still weather dependent

The province continues to keep a watchful eye on spring flood conditions, but says the true picture won’t be clear until winter is over.

The comments came from Infrastructure Minister Ron Schuler February 4, in a release announcing a new Basin Conditions Report that provided an updated snapshot of river levels and soil moisture conditions.

“The report will present Red River and Assiniboine River Basin conditions as of late January,” said Schuler in the release. “The actual extent of spring run-off is still largely dependent on weather conditions between now and April.”

As noted in the province’s Fall Conditions Report, soil moisture levels range from well-above average in southeast Manitoba including the Red River Valley, southwest and southeast Manitoba to near normal in northern Manitoba. In the United States portion of the Red River watershed, soil moisture levels were at record-high levels.

Since November 2019, precipitation is tracking below to well-below normal in most parts of Manitoba and Saskatchewan. However, precipitation in the United States portions of the Red and Souris rivers are tracking as much as 150 to 300 per cent of normal accumulation.

Frost depth is below normal in most areas. As moist and frozen soils reduce infiltration of meltwater and increase spring run-off, below-normal frost depth is considered a favourable condition in reducing the extent of spring run-off.

Base flows and levels in Manitoba rivers have been declining since the fall of 2019, but are still above normal for southern and northern Manitoba, and normal to above normal in central Manitoba basins.

Manitoba’s Hydrologic Forecast Centre is starting to build its first full Flood Outlook, which will be released in late February.

Forecasters will compile data from several sources including points south and west of Manitoba. Weather developments from now through April will largely determine the occurrence, extent and severity of spring run-off in 2020.

Spring run-off in Manitoba rivers is dependent on soil moisture, snow cover, soil frost depth, base flow and levels of rivers, along with the snowmelt rate and the amount and timing of the spring rain. Peak flows on Manitoba rivers are also dependent on the timing of peak flows from the United States and Saskatchewan portions of the basins.

The full Basins Condition Report is available at the Manitoba government website.

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