Week Comes To A Stormy End in Southern Manitoba

A complex low pressure system will bring several chances for thunderstorms to Winnipeg & the Red River Valley today and tonight into Saturday morning, some of which may be severe. All the unsettled weather will clear out on Saturday afternoon, leaving us with a seasonably mild and dry weekend.

The risk of thunderstorms returns to Winnipeg today as an approaching warm front moves into the region. As it advances eastwards, leftover cloud cover from overnight thunderstorms in Saskatchewan will spread into the Red River Valley. Before we get into the thunderstorm details, today’s high in Winnipeg will be a balmy 27°C with dew points climbing up to the 16-17°C range, making it feel a bit humid in the afternoon. Winds will be out of the south-southeast at about 20-30 km/h. Expect a low tonight near 18°C. Now, onto the thunderstorm details!

The first potential thunderstorm threat is for this afternoon, and will be focused primarily over southwestern Manitoba.

  • Moisture: Surface dewpoints will climb into the 15-17°C range ahead of the surface trough moving into the region. This moisture will be relatively deep, dropping only to around 13°C at 850mb.
  • Instability: MLCAPE values will climb to 1000-1500 J/kg of CAPE through the afternoon, although capping may be an issue depending on the timing of the 700mb thermal ridge passage.
  • Shear: Shear is fairly good with veering profiles and 45-50 kt of bulk shear. Low-level shear is relatively unidirectional with moderate speed shear.
  • Trigger: Low centre with trough line extending northwards will provide focus for low-level convergence. Additional, the triple point of a frontal wave tracking along the U.S./Canada border will also provide more focus and convergence.

The main uncertainties are tied to how quickly warmer air at 700mb1 can exit area. While it’s in place, it will likely prevent the development of thunderstorms until the evening. Should thunderstorms develop, the primary threats would be large hail and strong winds. The storms should be moving quickly enough that the threat for localized flooding due to rain is minimized, and higher cloud bases coupled with relatively small amounts of low-level wind shear will also reduce the tornado threat. If these thunderstorms develop, they will track eastwards into the Red River Valley in the early evening and make their way through.

The second thunderstorm threat will develop this evening and will impact much of southern Manitoba. Another disturbance will push into the region and initiate thunderstorms.

  • Moisture: The low-level jet will be supplying air with dew points near 16-17°C, providing ample moisture for thunderstorm development.
  • Instability: MUCAPE values will hover near 1000-1500 J/kg, enough energy to strong to severe thunderstorms.
  • Shear: Will be excellent; a very potent low-level jet will develop, strengthening to 50kt by 03Z. 500mb winds will be out of the west to southwest at 45-50 kt. This shear will be very supportive of thunderstorm development.
  • Trigger: Shortwave and associated frontal wave will be trigger for thunderstorm development.

Even now, there’s significant uncertainty with this afternoon’s convection. That said, it seems likely that thunderstorms will likely develop over portions of southwest Manitoba near 6-7PM and then undergo rapid upscale growth and develop into a line that tears eastwards across the Red River Valley; the primary threats associated with these storms will be large hail and damaging winds. Significantly elevated precipitable water values also suggest very intense downpours are likely as well.

AWM Thunderstorm Outlook valid 12PM Friday June 9 – 12PM Saturday June 10, 2017

Saturday will bring some more morning showers or thunderstorms, then breezy westerly winds of 30 gusting 50 km/h will usher in drier air in the afternoon as the clouds break up and clear out. Temperatures will climb up to a high near 23°C. Expect a low near 13°C under mainly clear skies on Saturday night.

Sunday will bring mainly sunny skies to Winnipeg with winds strengthening out of the southwest to around 30-40 km/h. Temperatures will climb to a high near 25°C. Winds will taper off Sunday evening as temperatures dip to a low near 15°C.

Long Range

Next week becomes quite uncertain as a major low pressure system develops in the Northern Plains of the United States and then slowly meanders northwards. As we move into summer, these systems will increasingly be driven by thunderstorms, which carry an inherent level of uncertainty, especially in the long range as how the various rounds of thunderstorm activity develop can impact the overall development of the low pressure system. That said, conditions will turn unsettled next week with near-seasonal to slightly above-seasonal temperatures.

Winnipeg’s seasonal daytime high is currently 23°C while the seasonal overnight low is 10°C.

An Additional Note

This will be the last forecast we issue here at A Weather Moment for the next while. We’ll be taking a bit of a vacation and won’t have our regular forecast posts on Monday June 12th or Wednesday June 14th. We suggest you check Environment Canada’s forecasts while we’re away!

  1. Approximately 3km above the ground.

Warm Weather Quickly Rebounds Back Into the Red River Valley

While today will bring cooler highs in the low 20’s to the Red River Valley, the break from the heat will be short-lived. High temperatures will quickly rebound back into the upper 20’s for both Thursday and Friday alongside plenty of sunshine!

Mostly cloudy skies will persist over the Red River Valley today as an upper-level trough moves through the region. The cloudier skies will temperatures lower than the 29-30°C seen over the last couple days; today will reach a high of just 22°C. Winds will be out of the north to northwest at around 15-25 km/h. Skies will clear out overnight as temperatures head to a low near 13°C.

Thursday will be a beautiful day as high pressure moves into the region and brings partly cloudy skies and much warmer temperatures as highs through the Red River Valley rebound to 27-28°C. Winds will be out of the south at 20-30 km/h and humidity levels will be comfortable.

Temperatures will rebound into the upper 20’s across the Red River Valley on Thursday.

Friday will start off with sunshine, but clouds will move in through the day as a low pressure system approaches from the west. Winnipeg may see a chance of shower in the afternoon. Temperatures will remain warm with highs near 28°C, and winds will strengthen out of the south to around 30-40 km/h. The chance for rain will continue on Friday night as temperatures drop to around 18°C.

Long Range

There’s quite a bit of uncertainty for the weekend, but the general idea is that Winnipeg may see a few bouts of showers or thunderstorms as a series of low pressure systems move through. The beginning of next week also looks unsettled, with a slow-moving low pressure system forecast to impact the region, bringing multiple chances for rain across several days.

Winnipeg’s seasonal daytime high is currently 23°C while the seasonal overnight low is 10°C.

Warm Weather Continues for Winnipeg

Winnipeg will continue to see above normal temperatures as an upper-level ridge basks the eastern Prairies in summer warmth. Conditions will turn more unsettled on Tuesday, though, with the chance of showers and thunderstorms moving into Southern Manitoba.

Today will be a beautiful day in Winnipeg as temperatures climb to a high near 29°C under sunny skies. Winds will increase out of the southeast to 20 km/h for the afternoon. There’s really not much to say about today; it’ll be great! Temperatures will dip to a mild low near 17°C tonight with partly cloudy skies.

Tomorrow will bring slightly more interesting weather to the region as a trough of low pressure pushes into the region through the morning. Skies will start off partly cloudy, but Winnipeg will see clouds increase through the morning. From midday into the evening, Winnipeg & the Red River Valley will see a decent chance of some showers or thunderstorms, but no severe weather is expected at this point. Temperatures will climb to a high near 26°C with breezy winds out of the south to 30-40 km/h in the morning becoming light for the afternoon.

A narrow band of showers or thunderstorms is possible on Tuesday as a trough of low pressure moves through the region

The clouds will stick around tonight along with a continued slight chance of showers as temperatures dip to a low near 15°C.

Wednesday will bring mainly cloudy skies to Winnipeg & the Red River Valley and slightly cooler temperatures with highs near 23°C and relatively light winds. There will be a continued chance for showers as a weak disturbance hangs back over the region behind Tuesday’s trough. Expect a low near 12°C on Wednesday night with light northerly winds and clearing skies.

Long Range

The remainder of the work week looks pleasant with daytime highs in the mid-20’s and mostly sunny skies. Heading into the weekend, it looks like the heat will return with Saturday potentially hitting 30°C once again, however things may turn stormy as multiple low pressure systems track through the region. We’ll be keeping an eye on things as we get closer to the weekend!

Winnipeg’s seasonal daytime high is currently 22°C while the seasonal overnight low is 9°C.

Summer Heat Brings First Significant Thunderstorm Risk of the Year

The mercury will soar today thanks to the significant upper-level ridge over the region that has brought very warm air into the province. That hot weather will moderate a bit for the weekend, though, as a low pressure system moving through tonight will bring a threat of thunderstorms to the region and push temperatures down closer to seasonal values.

A scorcher is on the way today as temperatures climb above the 30°C mark across much of southern Manitoba. Southerly winds around 30 km/h will help bring up some humidity from the United States, and by the afternoon it may actually begin to feel muggy as well.

The weather will turn later this afternoon over the southwestern corner of the province as a cold front pushes eastwards across the province. Thunderstorms will develop near the Saskatchewan border mid- to late-afternoon and then grow into a line along the cold front as they progress eastwards through the evening.

Thunderstorms are possible across Southern Manitoba today with a risk of severe thunderstorms over the Parkland, southwestern portions of the province, and the western Red River Valley.

The biggest risk for severe weather will be in the afternoon during the early stages of thunderstorm development. Thunderstorms will have more energy to work with with temperatures in the 30’s combining with dew point values in the mid-teens providing 2000-2500 J/kg of CAPE. Shear will be a bit lacking, at 20-35 kt of 0-500mb bulk shear depending on the position with respect to the cold front.

That said, there’s a slight risk of severe thunderstorms across southwestern Manitoba tomorrow with the primary threat being large hail. Some of these thunderstorms may also produce strong to severe wind gusts.

The energy and dynamics to support these storms will shift as the evening progresses, with the best support slumping into the United States. As the line moves into the Red River Valley, the threat for severe weather diminishes, however thunderstorms will likely continue to roll eastwards through the night.

The expectation for thunderstorms to decrease in severity as they progress eastwards is based on the belief that models are being too aggressive in their advection of elevated dew point values into Southern Manitoba. If higher dew point values pushing into the upper teens do in fact show up in the region, the threat for severe thunderstorms will persist all night, and there would be an increased likelihood of a severe squall line along the cold front. Strong linear forcing could produce bowing segments with severe winds should that outcome occur.

The Weekend

Saturday will bring clearing skies in the morning, and then a few afternoon clouds with a slight chance of another shower or thundershower in the afternoon. The showers will move down from the northwest on the backside of Friday’s low, but as of writing it seems like most guidance suggests the showers will stay to the north and pass through the Interlake. That said, there’s a chance Winnipeg may see a little more rain in the afternoon.

The GFS is an outlier forecasting widespread showers across Southern Manitoba on Saturday afternoon

Aside from that, it will be a pleasant day with a high near 26°C and westerly winds to 20-30 km/h. Temperatures will dip to around 15°C on Saturday night with clearing skies.

Sunday will bring mainly sunny skies and a high temperature near 25°C to Winnipeg. Winds will be 15-25 km/h out of the north. All things considered, a great day!

Winnipeg’s seasonal daytime high is currently 22°C while the seasonal overnight low is 9°C.