Unsettled Friday Leads Into A Hot Weekend

Notably warm and humid weather in place over Southern Manitoba today will bring a threat for severe thunderstorm activity across the region as a shortwave trundles through. An upper-level ridge will then begin to rebound back into the Southern Prairies in response to a digging trough off the western coast of North America, bringing even warmer air into the region thanks to the resultant southwesterly flow aloft that will develop.

Friday
29°C / 17°C
Mixed skies with risk of a thunderstorm
Saturday
30°C / 20°C
Mainly sunny; hot and humid
Sunday
32°C / 19°C
A few clouds; hot and humid

Friday: Thunderstorms Possible Midday

A weak mid-level shortwave trundling across the region will bring a risk of thunderstorms to Winnipeg & the Red River Valley today[1] as warm and humid weather meets the colder air associated with the shortwave. As always, using our MIST principles:

  • Moisture: Adequate. Moderate moisture will be in place both at the surface and through the lower levels of the atmosphere as deep-layer moisture continues to build into the region.
  • Instability: Favourable. With both thunderstorm possibilities, both elevated and surface-based, enough instability will be in place. Surface-based convection would have greater potential to be severe, however it will rely on strong surface heating with mainly sunny skies until the shortwave arrives, which could be in question depending on what sort of nocturnal convection develops.[2] If it does end up cloudy, strong mid-level lapse rates associated with the shortwave should be enough to sustain showers or thunderstorms as it heads eastwards. All said, storms should have around 1000–2000J/kg of CAPE to work with, depending on their exact timing and where they’re based.
  • Shear looks quite good with around 35kt of 0–6km bulk shear and gently looping hodographs. Low-level winds are weak enough that tornado activity doesn’t look like a particular threat, but the directional shear is favourable for the organization of supercell thunderstorms.
  • Trigger: The shortwave moving through coupled with a weak surface trough will provide the convergence and trigger for convective initiation.
AWM Day 1 Convective Outlook
A slight risk of severe thunderstorms exists in the Red River Valley and southeastern Manitoba today.

All things considered, it’s likely that we’ll see some activity at some point today. The primary threats with today’s thunderstorms will be large hail and strong winds. Storm motions will generally be towards the southeast. Later in the day, a more organized heavy rainfall threat may develop with any storms still ongoing.

Those things aside, it will be quite a nice day. Temperatures will climb to around 28 or 29°C with a few clouds through the day. The humidity will begin to be more noticeable as dewpoints climb into the high teens by the afternoon ahead of the weak surface trough/low moving through. Winds will remain light.

Things clear out tonight with the humidity remaining in place and temperatures dipping down to about 17°C.

Hot & Humid Weekend Ahead

Temperatures will soar this weekend as warmer air moves into the region and sends daytime highs to 30°C or higher. Saturday will be a sunny day with a high around 30°C and dewpoint values in the high teens or low twenties making it feel more like the upper 30’s. Winds will be light. Expect a low near the 20°C mark on Saturday night.

Manitoba Health – Heat Alert Response System in Relation to the Heat Dial
This weekend could see provincial (pictured above) or federal responses to the heat and humidity over the region.

Sunday will see the daytime high climb even higher, most likely towards the 32 or 33°C mark as breezy southerly winds develop ahead of a developing low pressure trough. The humidity will remain in place with dewpoints in the high teens or low 20’s, making it feel more like the upper 30’s. There’s a slight chance we may see humidex values hit 40 on Sunday, which is Environment Canada’s criteria for a heat warning. That said, both Saturday and Sunday will likely qualify for the Province of Manitoba’s Heat Advisory and Response Pre-Alert which requires a humidex of 37 or higher.

There appears to be a slight chance late Sunday night or early Monday morning for some showers or thunderstorms to move through the area, but it looks very conditional at this point and it’s far to early to say much about it. We’ll put an update here early Sunday afternoon regarding the precipitation potential for Sunday night. Temperatures will likely only drop to around 19°C on Sunday night, however.

Long Term: Slight Cool-Down to Start Next Week

Looking ahead, it seems like we’ll see a slight cool-down next week as a frontal boundary stalls out over the region and brings a chance for multiple bouts of unsettled weather through the first half of the week. We’ll have more details about that bright and early Monday morning!


  1. Exactly when depends on the timing which will be affected by how much and what type of elevated convection developed with this feature overnight in Saskatchewan.  ↩
  2. If the nocturnal convection is in the right spot or strong enough, our sunshine could be replaced by cloud cover instead, dramatically limiting surface heating.  ↩

Summer Temperatures Return as Quiet Weather Continues

Temperatures will be returning to more summer-like values through the second half of this week thanks to an upper-level ridge that will push out the cold air drawn southwards behind this past weekend’s big storm and allow more heat to begin building into the region.

Wednesday
27°C / 11°C
Mainly sunny
Thursday
28°C / 13°C
A few clouds
Friday
30°C / 16°C
Mixed skies, risk of a thunderstorm

The coming two days will be gorgeous with plenty of sunshine, light winds and warm temperatures. Today will see daytime highs near 26 or 27°C while Thursday will bring highs a degree or two warmer. Overnight lows both nights will be near 12°C. The most significant weather feature will be the significant amounts of smoke that will be pushing into the region sourced from wildfires raging in the northwestern United States. At this point, it seems like it should mainly be aloft and not pose much of an air quality issue.

NAM Forecasted MUCAPE & Bulk Shear valid Friday evening.
The NAM is showing large values of CAPE (energy) and shear on Friday afternoon which suggests the potential for severe thunderstorms.

Friday will see a low pressure system moving through the region, bringing warmer temperatures alongside a thunderstorm threat. The major question mark, at this point, appears to be whether or not any smoke in the region inhibits temperatures from climbing high enough to trigger thunderstorms or not. That said, it looks like the potential will be in place for severe thunderstorms with over 3000 J/kg of CAPE expected and over 50 kt of bulk shear in place.

We’ll be taking a closer look at the severe thunderstorm potential on Friday morning in the next blog post, but for now, just keep aware that the threat for severe weather may return to the Red River Valley on Friday.

Other than the storm potential, daytime highs should sit near 30°C with mixed skies. There’s also a reasonable chance that it will be quite humid, making it feel more like the upper 30’s.

Heading through the weekend, it looks like Winnipeg & the Red River Valley will see highs near 30°C with plenty of sunshine, making up for the miserable weather during the last weekend. Other than the blip on Friday, there’s plenty of warm, dry and sunny weather ahead, so enjoy!

Slowly Warming Up

Conditions will slowly warm this week as the weekend’s potent weather system departs our region. Temperatures should return to seasonal values by midweek.

Monday
19°C / 6°C
Mainly sunny
Tuesday
22°C / 9°C
Mainly sunny
Wednesday
27°C / 16°C
Mix of sun and cloud

Monday

Today will remain on the cool side, with high temperatures in the upper teens. Winds will remain gusty as well, as we continue to deal with the stiff north-west flow behind the weekend’s low pressure system. Skies will finally become sunny however, which is a welcome change from the grey and rainy conditions of the weekend.

Tuesday

Tuesday will see temperatures warm further, with highs reaching the low twenties. Skies will remain mainly sunny and winds will be light making for a nice day.

Wednesday

Wednesday should see temperatures climb back toward seasonal, or even above-seasonal values. High temperatures will be in the mid to upper twenties as we return to a mild southerly flow. Skies may be somewhat variable due to the passage of an upper-level disturbance.

Northern Hemisphere Waters Seeing Increased Storm Activity

The hurricane and typhoon seasons (Atlantic and Pacific basin, respectively) both ramped up this past week as three significant storms spun up with another one expected to strengthen.

Different model tracks for Danny - some models want to curve it northwards faster than others. (Source: Tropical Tidbits)
Different model tracks for Danny – some models want to curve it northwards faster than others. (Source: Tropical Tidbits)

The first, hurricane Danny, formed a few days ago west of Cape Verde Islands, in the Atlantic basin. The conditions in the past days were good for steady intensification, until about Friday midday when the hurricane encountered dry air and began ingesting it. Before then however, a recon plane flew into Danny and registered winds that suggested the storm was already a major hurricane, of category three on Friday morning. This is the first major hurricane of the Atlantic this year and the earliest since 2009. As Danny is still far from the US mainland it is impossible to say which states it will affect, if any at all. Before then however, it is expected to move through the northern Antilles, but only as a tropical storm due to the fact that it will continue to gradually weaken due to high shear/dry air present east of the Antilles.

Two typhoons are also currently spinning simultaneously in the western Pacific, one off the western coast of Thailand (Goni), and one further west (Atsani). These were both once very powerful typhoons, of category four and five (super typhoon), respectively. They have since gradually weakened to category two equivalent storms however. Neither of them are expected to make direct landfall, but Goni has already had adverse effects on the northern Philippines and Thailand, bringing heavy rain and fairly strong winds as it brushed the islands. What is special about these two very powerful storms (category four and higher) was that they were churning in the western Pacific simultaneously, a feat that is fairly uncommon.

Beautiful satellite image taken on the 20th that captures both Goni and Atsani in the western Pacific. (Source: NASA)
Beautiful satellite image taken on the 20th that captures both Goni and Atsani in the western Pacific. (Source: NASA)

Finally, the last storm of concern is tropical depression Kilo, located southeast of the Hawaiian Islands. As of Friday night Kilo was only a weak storm with sustained winds of 60km/h. However, Kilo is expected to continue curving northwestwards towards the Hawaiian Islands and strengthen. National Hurricane Centre is forecasting that it will strengthen to a category two hurricane and could come very close to making landfall on the island of Kauai. There’s still some uncertainty of its exact track this far out but it appears that this will be a major event for at least the western Hawaiian Islands.