Four things you need to know about Monday, July 21

Monday, July 21, 2014, 7:58 AM - Wondering what you missed overnight or what you can expect for the day ahead? 

Here's your weather briefing for Monday, July 21.

1. Dense fog slows morning commute in southern Ontario

Dense fog slowed the early morning commute for drivers across southern Ontario Monday.

Yikes! #Foggy. RT @BTT_GTA: This is a look at the 410 North of the 401! Drive safe! #trafficandweather #gta #BTT pic.twitter.com/q6j0JiwKaG

— Emily Vukovic (@EmilyTWN) July 21, 2014

"Near zero visibility in fog is likely until mid morning," said Environment Canada in a fog advisory issued for the region. "Visibility may be significantly and suddenly reduced to near zero. If traveling, be prepared for areas of near zero visibility."

2. Humidity builds into northern Ontario, significant rain in thunderstorms likely

Tornado watches and warnings were issued in northwestern Ontario Sunday, ahead of a system that brought severe thunderstorms to the region.

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The chance for more severe storms is possible again Monday in southern Manitoba and northwestern Ontario, with strong winds and significant rainfall being the greatest threats.

"Current indications suggest that some areas may see 30 to 40 millimetres of rain tonight," said EC in a special weather statement early Monday. "Even higher amounts are possible locally in areas that receive several thunderstorms. The area of heavy rain is then expected to affect areas north of Lake Superior towards James Bay mainly on Tuesday."

A heat warning is also in effect for some places as a warm and humid airmass remains in place.

"Areas near the Minnesota border will likely see humidex values of near 40 during the afternoon," adds EC.

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Heat warnings are issued when very high temperature or humidity conditions are expected to pose an elevated risk of heat illnesses, such as heat stroke or heat exhaustion.

"Drink plenty of liquids especially water before you feel thirsty to decrease your risk of dehydration. Thirst is not a good indicator of dehydration," officials warn.

3. Tornado footage from a fallen soldier

On July 18 every year, Wendy Hayward takes time to remember and reflect.

On that day in 2008, her son, Corporal James "Jim" Arnal, born in Kelvington, Sask., was out on foot patrol when he was killed by an explosive device, becoming the 88th Canadian soldier to die during the Afghanistan mission. He was 25.

As she always does when the anniversary of her son's death comes around, Hayward took the day to go through her memories of her son, but this time her search through his effects turned up something very unexpected: Video footage of Arnal and his friends, driving their car past a massive tornado.

To read more about this incredible story, check out this article from digital reporter Daniel Martins.

Today's thunderstorm risk for the Prairies:

4. Poor air quality remains in B.C.

Firefighters are hopeful cooler, wetter weather will continue to help bring fires under control.

According to the B.C. Wildfire Management Branch, a change in weather has allowed firefighters to contain 50 per cent of the blaze near West Kelowna, which forced 2,500 people from their homes.

Despite improving weather conditions however, a special air quality statement remains in effect for several communities.

"A wildfire smoke advisory is in effect for the omineca region and north East British Columbia including Quesnel, Vanderhoof, Prince George, Mackenzie, Chetwynd, Dawson Creek, for St. John, and Fort Nelson," the statement reads. "A wildfire smoke advisory is also in effect for the East Columbia including the town of Golden, and parts of the Kootenays including Creston and Castlegar, and their surrounding areas."

Persons with chronic underlying medical conditions are being urged to postpone strenuous exercise until the advisory is lifted.