Monday will bring Winnipeg fully into the tropical airmass that has been building to our south for the past several days. As the upper ridge over the central United States continues to push north, Winnipeg and the rest of the RRV will want to break out the air conditioners.
A building upper ridge will continue to push north out of the United States into Southern Manitoba overnight and tomorrow. After a very slight chance of rain or a thunderstorm in the morning, the temperature will soar into the low 30’s through much of Southern MB. Dewpoints close to the SK border will be low enough to not warrant too much of an issue, but as you move east towards the RRV, positively tropical dewpoints of 22C to 25C will persist resulting in Humidex values reaching into the low 40’s.
Fortunately, unlike as was forecast in the long range models last week, there is a fairly consistent agreement that the hot weather will not last. A large MCS is forecast to develop on Tuesday night in northeastern Montana, which will likely head west of Winnipeg, however for most of the day we will be clouded over with debris cloud from the system and have a chance of showers or thunderstorm. Tuesday will still be muggy, however, with dewpoints still in the low 20’s. With all the cloud, though, the temperature will only climb into the mid 20’s instead of the low 30’s.
After that a powerful impulse is forecast to sweep across the northern Prairies on Wed/Thur/Fri, which will bring Winnipeg into a drier air mass next week.