Winnipeg will see its hottest days of the heat wave ahead, but some relief will begin to work into the region on Sunday.
The massive upper high over the region will keep skies mainly sunny over the next two days and temperatures hot. Daytime highs will reach the mid-30s today and tomorrow in Winnipeg. Fortunately, the dew point will stay a comfortable range through the next couple days. Although it won’t be humid, the heat will be intense with little relief at night; lows will only reach around 22 or 23 °C both tonight and tomorrow night.
A trough approaching the province on Saturday will bring breezy southerly winds of 30–40 km/h and some afternoon cloud to the Red River Valley. Heading into the night, the trough will bring a chance of showers or thunderstorms to the region as it moves into the Red River Valley.
The chances for any rain will taper off on Sunday morning as the trough moves through. In its wake, breezy northwest winds in the 30–40 km/h range will develop. Skies should clear out in the afternoon with a high near 32 °C. Temperatures will head to a low near 18 °C on Sunday night
Long Range Outlook
Temperatures will return to seasonal values for the start of next week with variable cloudiness. Conditions look likely to turn unsettled around mid-week, with the potential for a couple rounds of showers/thunderstorms in the second half of the week.
Today’s seasonal daytime high in Winnipeg is 25 °C while the seasonal overnight low is 13 °C.
Winnipeg’s daytime highs will slowly warm this week as the immense dome of hot air over western Canada slides eastwards.
Winnipeg’s forecast: sunshine and heat. A potent upper high continues to sit over western Canada continues, baking British Columbia and the Pacific Northwest with record-shattering heat. This upper feature will slowly move from southern Alberta into Manitoba over the second half of the week.
To start off Wednesday, the Winnipeg area will see a few clouds as the remnants of some overnight convection in the Interlake drift south. There’s a small chance that some of the activity will survive into the region, but anything remaining will taper off quickly through the morning. As the upper high approaches, conditions will stabilize over the province and temperatures will climb. Winnipeg’s high will increase from around 31 °C today to 35 °C by the end of the week. Overnight lows will also creep towards the 20 °C mark.
Intense heat will spread through the entire Prairies this week. Virtually everywhere that isn’t near a notable body of water will see temperatures climb into the mid- to upper-30s by Friday.
Winds will stay light over the next few days, gradually shifting from northerly today to southerly by Friday. The forecast shows no chance for rain.
Long Range Outlook
The heat will increase further this weekend with highs climbing into the upper 30s on Saturday. The heat will ease back to the low 30s on Sunday, then into the upper 20s to start next week. Some instability is forecast to return mid-week as temperatures once again climb back into the 30s.
Today’s seasonal daytime high in Winnipeg is 25 °C while the seasonal overnight low is 13 °C.
Winnipeg’s hottest, most humid day of the year is on the way with humidex values forecast to climb over 40 on Saturday. A cold front will push across the province Saturday evening, bringing the risk of severe thunderstorms to the region.
An upper-level ridge building over the Prairies will spread a southerly flow over Manitoba today. Tapping into Gulf of Mexico moisture over the American Plains, this southerly flow will draw very humid conditions northwards into the Red River Valley for Saturday.
Before that happens, though, Winnipeg will see a breezy and warm summer day today. Under sunny skies, temperatures in Winnipeg will climb to a high near 29°C with a southerly wind increasing to around 30 km/h midday then closer to 40 km/h by the evening. Those winds will keep the boundary layer well mixed through the night and keep the overnight low mild; Winnipeg should see a low near 21°C.
An extremely humid air mass will build into southern Manitoba for Saturday.
If you have a sensitivity to heat, then Saturday will be bringing dangerously hot weather into the region. A strong southerly wind near 40 gusting 60 km/h will continue to tap into the humid air mass to the south, pushing dew points into the low 20s across southern Manitoba. The humid weather will combine with daytime highs in the mid-30s – Winnipeg should see a high near 34°C – to produce humidex near or over 40. Humidex values are forecast to be most stressful1 between around 1PM and 8PM.
Skies will remain fairly sunny until a cold front arrives in the afternoon, bringing with it the threat of [severe] thunderstorms. While it’s a bit early to say too much with regard to the overall threat posed to the region, it goes without saying that a cold front pushing through that hot and humid air mass will pose the threat for severe weather. With over 4000 J/kg of MLCAPE forecast alongside 35 to 45 kt of 0-6 km bulk shear, the cold front would favour the development of discrete supercell thunderstorms capable of all modes of severe weather (very large hail, damaging wind gusts, and tornadoes).
The hot and humid weather will create an extremely high energy environment capable of supporting severe thunderstorms.
The biggest unknown at this point is where exactly the thunderstorms will develop. A strong capping inversion should keep things quiet for most of the day, but thunderstorms will likely fire along the cold front early in the evening. Current forecasts place the cold front near or just east of the Red River near 6PM, making the threat conditional for the Red River Valley. Eastwards, towards the Whiteshell and the rest of southeastern Manitoba, the threat will be much greater.
Behind the cold front, westerly winds will begin to ease the humidity as the temperature heads to another mild low near 19°C.
Sunday will bring another sunny day to Winnipeg with northwesterly winds at 20 to 30 km/h and a high near 29°C. The dew point will continue to drop into the low teens, making for a much more comfortable day. Temperatures will drop to a low near 16°C on Sunday night under mainly clear skies.
Long Range Outlook
Next week looks like a prototypical July week: a fair amount of sunshine, plenty of warm days with daytime highs in the upper 20s, mild lows in the upper teens, and a chance for some showers or thunderstorms. The week looks great, but there is a chance that Winnipeg will see thunderstorms late Tuesday through the overnight.
Winnipeg’s seasonal daytime high is currently 26°C while the seasonal overnight low is 13°C.
We identify stressful humidex values as those which exceed the body’s normal temperature of 37°C. ↩
