Stormy Tuesday Brings The Heat

The heat will be cranking up over the Prairies this week, and Winnipeg will see increasing warmth through the start of the week. A potentially stormy Tuesday will be a marked turning point as hot and muggy weather moves into the region. Heading into the second half of the week, conditions will be more settled but the heat sticks around for the foreseeable future.

A major pattern shift is underway that will bring a prolonged period of heat to much of western North America. Winnipeg will begin feeling the impact today as temperatures climb towards a high of 27°C under mixed skies. Winds will pick up out of the south-southeast to around 20 km/h in the afternoon as low pressure system begins approaching the province from Saskatchewan. The humidity will remain relatively comfortable today, though, with dew point temperatures expected to remain around 13 or 14°C.1

Winds will continue out of the south-southeast tonight with temperatures remaining warm overnight; the expected low is just 17°C as a warm front pushes across the Red River Valley.

The RDPS shows an organized line of thunderstorms developing on Tuesday afternoon.

Summer will arrive in all forms for Winnipeg on Tuesday. Now in what’s known as the warm sector, the humidity will rise quite quickly on Tuesday morning with dew points reaching around 18-19°C. Temperatures will climb towards a high of 29°C which will feel closer to the mid-30’s with the humidity factored in. For the afternoon, attention will turn towards the potential for severe thunderstorms as a cold front pushes southeastwards into the Red River Valley.

Going over the MIST ingredients:

  • Moisture: Plenty of moisture available with dew points in the upper teens being fed into any storms that develop. Moisture also seems to be relatively deep, so dramatic reductions due to mixing are unlikely.
  • Instability: MLCAPE values climb towards the 2000 J/kg mark with marginal capping. The low-level inversion will erode with the injection of 850 mb cooling while 700 mb temperatures remain below the 10°C threshold.
  • Shear: Surface – 6km bulk shear values peak around 30 kt which would be ample for storm organization.
  • Trigger: Two primary foci for convection: a pre-frontal trough that moves through midday, and then a cold front that pushes into the region mid- to late-afternoon.

These thunderstorms may be severe with the primary threats being large hail and localized flooding due to intense downpours. Strong wind gusts are possible with these storms as well. At this point, it seems like a tornado threat is unlikely, but we’ll keep an eye on things as they develop.

After the cold front slides through, winds will shift out of the northwest at around 15-25 km/h and the humidity will begin to ease as drier air moves into the region. Temperature will still remain warm, though, with overnight lows dropping only to around the 17°C mark once again.

Wednesday will be another hot day with temperatures climbing to around the 28°C mark with partly cloudy skies in the morning. The humidity will be much more comfortable than on Tuesday thanks to drier air that works in through the day and drops dew points back down to the low teens for the afternoon. Expect a low near 17 or 18°C on Wednesday night with a slight chance of another shower or thunderstorm as a weak disturbance slides through the region.

Long Range.

Looking further ahead, temperatures will cool towards seasonal to round out the work week as slightly cooler air moves in behind Wednesday night’s disturbance.

NAEFS 8-14 Day Temperature Anomaly Forecast — Valid July 10 – 17, 2017

The heat begins building back in through the weekend, and next week is looking quite warm and relatively humid as an upper ridge builds over the western Prairies, spreading above-normal temperatures across the region.

Winnipeg’s seasonal daytime high is currently 25°C while the seasonal overnight low is 13°C.

  1. The dew point only begins having a significant impact on how hot and/or muggy it feels once it begins climbing above 15°C or so. 


Brad lives in Winnipeg with his wife and two children and is the founder of A Weather Moment. He has loved weather from a very young age and has followed that passion through his life so far. He received a B.Sc. in Earth Sciences with Specialization in Atmospheric Sciences and is currently employed in the field of meteorology. You can find the author as WeatherInThePeg on Mastodon.

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