While July has been relatively pleasant, temperatures have [somewhat surprisingly] been largely below seasonal for much of the month. That’s all about to change as significant heat builds across the region to round out the month.
A developing southerly wind of 20-30 km/h this morning will draw warmer air northwards out of the United States and help push daytime highs up to around the 30°C mark. Skies will remain mainly sunny and humidity in the mid-teens should keep things feeling relatively comfortable. Expect lows to fall to around the 19°C mark tonight with winds continuing out of the south and partly cloudy skies.
Saturday will see a cold front slowly sweeping across the province, bringing with it a severe thunderstorm risk. Before that, though, there will be a hot summer day on tap with highs once again near the 30°C mark under mixed skies. With the southerly winds slowly diminishing and dew points rising to around 19 or 20°C, it will end up feeling quite humid in the afternoon. The cold front will progress eastwards through the day, reaching the Red River Valley mid- to late-afternoon. As it pushes into the valley, it will bring with it the risk of severe thunderstorms.
Going over the MIST ingredients:
- Moisture: Low-level moisture will be plentiful with surface dew points climbing towards the 20°C mark and with deep moisture extending towards 850 mb.
- Instability: Slight to moderate instability will be in place. Mid-level lapse rates leave a bit to be desired with expected values only around 6-7°C/km, but this is somewhat offset by the substantial latent heat available through surface moisture. Depending on the exact orientation of this system, the heights may be rising as the front stalls, which would work against thunderstorm development.
- Shear: Bulk shear values around 25-30 kt will be in place which is on the lower end of values. Low-level shear will likely be weak and mid-level shear largely unidirectional.
- Trigger: The cold front will slowly slump southeastwards, gradually slowing into the evening hours.
The primary threats with any storms that develop will be large hail and damaging winds, although with dew points so high, torrential rain is likely as well. They would move southeastwards through the Red River Valley. The biggest question will be whether or not storms actually develop. The threat will exist generally around the Trans-Canada Highway corridor and south, but we’ll provide an update on Saturday with a new look at the day’s potential.
The thunderstorm threat will diminish before midnight and temperatures will then drop to a low near 17°C under clearing skies.
Sunday will be another hot day with a high near 31°C but more comfortable humidity as the dew point drops back towards the mid-teens. Skies will be partly cloudy and winds will be light out of the east. Winds will shift out of the south on Sunday night and increase to 15-25 km/h, keeping temperatures fairly warm; the overnight low will be just around 19 or 20°C.
Long Range
Temperatures will continue to be warm through the start of next week with partly cloudy skies and highs generally around the 30°C mark. Monday will likely be moderately humid again, but things will dry out on Tuesday as a cold front moves through. The rest of the week looks fairly quiet with near-seasonal temperatures and low humidity.
