The City of Winnipeg and much of the Red River Valley may see their first large thunderstorm of the season on Sunday.

"Considering the conditions and substantial potential for severe thunderstorm development Sunday afternoon and evening in the Pembina and Red River Valleys we need to shift our thinking into severe Summer weather mode today," says CMOS Accredited Weathercaster Chris Sumner.

Sumner who is reminding Manitobans that severe thunderstorm season is here, and they need to plan accordingly.

"Strong southeasterly winds Sunday will pump the atmosphere full of a warm, moist air-mass as a warm front moves northward out of the Dakotas," explains Sumner Saturday morning. "The current forecast models are indicating storm development mid to late afternoon, and continuing into the evening hours."

Sumner says that considering the high level of instability in the atmosphere and the potential for supercell thunderstorms (the strongest type of thunderstorms) developing, most types of severe weather will be possible including very heavy rainfall, large hail and strong wind gusts of more than 110 km/h.

Sumner adds the risk for tornadoes can't be ruled out, but noted it was a small risk, and primarily for areas near the U.S. border.

Seeing how this is the first significant risk of severe thunderstorm development this season, Sumner stresses the importance of knowing the forecast before heading out the door Sunday, and keeping on top of changing conditions/watches/warnings and having a plan for where and how to take shelter in the event of severe thunderstorms developing.

"Being prepared ahead of time, and having that plan in place, is crucial if you're going to be away from your home," explains Sumner. "Thunderstorms can develop very quickly, and being caught off guard with no plan or way to receive updated notifications, puts you at risk."