Summer Scorcher Gives Way to Seasonal Conditions

A heat warning is in effect for Winnipeg with another two days of sweltering, increasingly humid, weather on the way. A cold front will move through Saturday evening, though, bringing a risk of thunderstorms and a return to seasonal temperatures.

Winnipeg will see daytime highs well over 30°C both today and tomorrow as an upper level ridge moves through. Temperatures will climb to a high near 32°C today under sunny skies. Winds will increase out of the west-northwest from light this morning into the 20-30 km/h range this afternoon. Winds will diminish to light tonight as temperatures dip to a low near 19°C. Saturday will be a scorcher. Southerly winds will strengthen to 40 gusting 60 km/h and draw a more humid air mass northwards. With highs expected to reach 34 or 35°C alongside dew points in the upper teens, Winnipeg will see another day with humidex near 40.

A sharp cold front will surge southeastwards through the Red River Valley on Saturday evening.
A sharp cold front will surge southeastwards through the Red River Valley on Saturday evening.

A sharp cold front sweeping southeastwards will bring a moderate threat of severe thunderstorms to the Red River Valley late Saturday afternoon into the evening. Going over the MIST ingredients:

  • Moisture: While surface moisture will likely be plentiful, it won’t be particularly deep. The southerly wind should help sustain moisture transport, though, with deeper moisture near the cold front likely as it pools.
  • Instability: With high surface moisture, SBCAPE values are impressive with over 3500 J/kg forecast. However, MLCAPE values will likely be substantially less in the 1000 to 2000 J/kg range as the moisture drops off with elevation.
  • Shear: Shear is moderate with 25 to 35 kt of 0-6 km bulk shear forecast. As storms progress into the evening, 20 to 30 kt of effective shear is forecast.
  • Trigger: Strong convergence along a cold front sweeping southeastwards.

The most likely scenario at this point looks like scattered thunderstorms will develop along the cold front in the late afternoon, stretching from the southern Interlake into southwestern Manitoba. These storms will push southeastwards into the Red River Valley, but timing will be important; winds are forecast to weaken aloft as the evening progresses, likely meaning that these thunderstorms will weaken as the evening progresses. The primary threat these storms will pose will be damaging hail and/or winds. The tornado threat looks low right now.1

Winds will shift north-westerly behind the cold front at 15 to 25 km/h as temperatures head to a low near 15°C.

Sunday will be a relatively pleasant day in Winnipeg. Temperatures will climb to a seasonal high near 25°C under partly cloudy skies, but winds will strengthen out of the west to around 30 gusting 50 km/h. Winds will ease on Sunday night with a low near 14°C.

Long Range Outlook

Winnipeg will see plenty of sunshine to kick off next week with slightly below-seasonal to seasonal temperatures. Warmer weather returns mid-week as an upper ridge builds back into the eastern Prairies. Unfortunately, rainfall remains elusive. No widespread relief is on the way for agricultural regions beginning to experience heat and moisture stress.

Winnipeg’s seasonal daytime high is currently 26°C while the seasonal overnight low is 13°C.

  1. If surface winds back a little more than currently forecast, tornadoes may be a threat with these thunderstorms, primarily through the late afternoon and early evening.

 

Winnipeg Continues To See Hot Summer Conditions

After an unsettled start early Wednesday morning, Winnipeg will see plenty of sunshine and hot weather for the remainder of the work week.

Winnipeg will see a generally unsettled morning today as a low pressure system rolls into Manitoba. The bulk of it will have occurred with the convective complex that has moved through the city early this morning, but a few more showers are possible along a cold front moving through later today. Before that happens, hot and muggy conditions will develop under mixed skies; temperatures will climb to a high near 32°C with dew points near 20°C. This will result in humidex values in the upper 30s. Once the cold front moves through, any lingering chance for showers will taper off, skies will clear, and drier air will begin working into the region from the west. Winnipeg will see a mild low near 19°C tonight under clear skies.

Winnipeg will see hot and humid conditions before a cold front pushes through Wednesday afternoon.

The next two days will bring more beautiful summer weather to the city as a ridge of high pressure builds in. Winnipeg will see mainly sunny skies both Thursday and Friday with daytime highs near the 30°C mark. Conditions won’t be too humid, and both days will see westerly winds; Thursday should see stronger winds in the 30 to 40 km/h range while lighter winds near 20 km/h move in for Friday. Lows will continue to be mild in the 17 to 20°C range.

Long Range Outlook

More warm weather is on tap for Saturday with daytime highs once again climbing above 30°C. A strong cold front passing through on Saturday night looks to bring a risk of thunderstorms to the region, followed by the arrival of a more seasonal air mass. The start of next week looks to bring plenty of sun, daytime highs in the 23 to 27°C range, and overnight lows in low to mid-teens.

Winnipeg’s seasonal daytime high is currently 26°C while the seasonal overnight low is 13°C.

 

Sweltering Summer Heat Will Bring Severe Thunderstorm Threat

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.

  1. We identify stressful humidex values as those which exceed the body’s normal temperature of 37°C.

 

 

 

Unsettled Wednesday Gives Way to Sweltering Summer Heat

After an unsettled morning, Winnipeg will see calmer weather and warming temperatures as an upper ridge builds across the Prairies.

Winnipeg will be starting the day with some unsettled weather as a line of thunderstorms moves through the Red River Valley. The stormy weather should clear out a bit later in the morning, leaving behind mostly cloudy skies and humid conditions. Dew points near 20°C will make temperatures in the low 20s feel more like 30 this morning. A cold front will pass through near lunch, bringing westerly winds to around 30 km/h. Along with the wind, markedly drier air will move into the the Red River Valley. Thanks to that, Winnipeg’s high near 25°C should feel comfortable by mid-afternoon. Under clear skies and a light west wind, Winnipeg will head to a low near 15°C tonight.

Conditions will settle quickly in the wake of Wednesday’s cold front. Hot on its heels, an upper-level ridge will begin building into the Prairies and bring sunny skies and increasingly warm weather. Winnipeg will see mainly sunny skies on Thursday with a seasonal high near 25°C. Winds will remain out of the northwest at around 20 km/h.

A ridge of high pressure will move through on Thursday night, bringing light winds, clear skies, and a low near 15°C.

An upper-level ridge will begin building across the Prairies on Friday.

Friday will mark the start of the warm-up as a southerly return flow develops behind the high. Winds will be light out of the south with sunny skies and a high near 27°C with comfortable humidity. Warmer air will continue to build into the region on Friday night, resulting in a mild low near 19°C.

Long Range Outlook

The weekend will be a scorcher as heat and humidity surge northwards into the region. Saturday will see temperatures climb into the low 30’s with dew points climbing into the upper teens. Humidex values on Saturday will climb towards 40. With all the heat and humidity, it does look like there will be a chance for thunderstorms. A “cool” front sweeping across the province on Saturday evening will bring the threat of severe weather back to Winnipeg. Sunday will still be warm with a high of 28 or 29°C, but the humidity will be much lower making for a comfortable summer day.

The warm weather will continue into next week with daytime highs expected to remain in the upper 20s with overnight lows near 18 or 19°C.

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