Heavy rainfall is creating havoc with watersheds across northwestern Ontario today. 

The Ministry of Natural Resources in the Thunder Bay district, has declared a flood outlook for the western portion of the region.

"People in the Shebandowan, Raith and Upsala areas, should ... be aware of the potential for flooding, based on the weather conditions we have and the forecast for heavy rain," said Patrick Gidley, MNR district planner for Thunder Bay.

"The watersheds are high right now and, obviously, with additional water coming into the system, there is potential for flooding."

Most rivers and streams in the region are swollen already, and rising water may impact water crossings, Gidley noted. He said flooding in low-lying areas may persist for some time. 

Road washout

Earlier today, provincial police closed Highway 11 west of Fort Frances due to a road washout.

"Heavy amounts of rain falling overnight have resulted in both lanes of the highway being completely washed out," Cst. Anne McCoy said.

Drivers travelling between Fort Frances and Emo are being diverted to Highway 602. McCoy said the Ministry of Transportation is assisting with the highway closure points. Canada Border Services and emergency services were also notified of the closure and traffic diversion.

Significant rainfall today and tonight

The low pressure system that has been tracking across northwestern Ontario will continue to do so this evening, and the city of Thunder Bay can expect more showers overnight.

A warning preparedness meteorologist with Environment Canada said there is a gradual clearing starting in the very far west of the province, and most areas of northwestern Ontario will be sunny by Friday, with a high of 20 C — a bit cooler than average for this time of the year.

"But the bad news is it starts all over again late on Saturday or Sunday, so we have more rain in store, particularly on Sunday," Peter Kimbell said.

On Saturday another system will be moving toward northwestern Ontario from the Dakotas, Kimbell noted. That system will bring rain to Kenora and Fort Frances again on Saturday and will be moving into the Thunder Bay area late Saturday evening or overnight.

"Amounts ... are too difficult to pin down at this stage but it looks like, unfortunately, for the people in Fort Frances and Atikokan, they may get the most again of this next system on Sunday," Kimbell said.

"So not very good for those folks they've already had so much rain and there's localized flooding going on."

As of 2 p.m. in Thunder Bay on Thursday, Thunder Bay's rainfall was nowhere near as much in the Western parts of northwestern Ontario. Fort Frances received 71 mm, Atikokan had 42 mm, and Dryden and Sioux lookout both received 32 mm and 33 mm.  Thunder Bay only received about 6 mm

The high level of precipitation led H2O Power to advise that flows from the Raft Lake Dam on the Seine River near Atikokan will be fast, in excess of 150 cubic meters per second.

High flow conditions are expected to continue for several days, as water moves through the river system with flows into the lower Seine River at Calm Lake and Sturgeon Falls dams increasing as well.

In an email to CBC news, H2O Power advised the public "to reconsider use of all activities along the Seine River until flood warnings have been terminated and levels/flows have receded towards normal conditions."

Weather watchers get training

Weather watchers in the northwest are learning this week how to properly spot and report extreme weather to Environment Canada.

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Geoff Coulson, a warning preparedness meteorologist with Environment Canada, is teaching a series of workshops across the region where volunteers are trained to be the department's eyes on the ground — and the skies — during storms. (Supplied)

Geoff Coulson, a meterologist with the weather service, is giving a series of workshops across the region, where volunteers are trained to relay information to the department during storms.

Coulson said weather spotters play an important role.

“Things like radar, satellite imagery, and lightning detection systems can give the forecasters a pretty good sense that a storm could be severe,” he said.

“But oftentimes the final piece of the puzzle will be that confirmation from someone on the ground, in terms of large hail size or damage done from damaging winds.”

'Eyes and ears for Environment Canada'

Coulson trained about 26 people in Thunder Bay on Monday, and has two sessions in Kenora on Thursday. Training will be wrapped up with sessions in Dryden on Friday.

Describing these weather watchers as "the eyes and ears for Environment Canada", Coulson said most of their volunteers are involved with amateur radio, although people from other walks of life are getting involved too.

"It helps us to get a better sense of the severity of certain types of storms by having these trained eyes on the ground to tell us what's going on."

“Even with the state of the science right now, in terms of forecasting, oftentimes we can only provide 10 to 15 minutes advance notice before a tornado occurs — maybe 20 to 25 minutes before a severe thunderstorm is expected to strike. So these ... volunteers can help [and] perhaps lengthen those lead times a bit."

Coulson added Environment Canada still takes observations from the general public too.