Category: Forecasts

Summer Warmth and Smoke Lead into an Unsettled End to the Weekend

Brad 1 Comment

Widespread smoke will remain in place today as a northwesterly flow gradually lightens and leaves the smoke to languish across Southern Manitoba. A low pressure system tracking into the northern Prairies tonight will bring a southerly flow at all levels to Southern Manitoba which will help clear skies out as well as lead towards an unsettled end to the weekend.

Today will bring partly cloudy skies which will seem a whole lot cloudier thanks to the widespread smoke that remains entrenched over Southern Manitoba today. That smoke will keep our temperatures slightly cooler than they would be under clear skies, leaving us with a high temperature later today of 26°C. Winds will remain fairly light through the day. The humidity will be more comfortable than yesterday’s dew points of 20°C; dew point values are expected to sit in the low- to mid-teens this afternoon.

Winds will begin picking up out of the south overnight which should help begin clearing the smoke out of our area. Our temperature will dip down to around 17°C.

Saturday will bring the humidity back to Southern Manitoba alongside gusty southerly winds to 30–40km/h. It will be quite a warm day with temperatures soaring into the upper–20’s or even hitting the 30°C mark while dew point values climb back towards the 20°C mark as the southerlies bring in more humid air from the Northern Plains.

GDPS 12hr. QPF valid Sunday morning.
The GDPS continues to forecast a swath of nocturnal convection occurring on Saturday night.

Saturday night will see thunderstorms initiate over Western Manitoba then slowly push southeastwards. There will likely be a chance for some severe thunderstorm activity over Parkland Manitoba; we’ll take a closer look and issue a convective outlook if warranted tomorrow. These showers and thunderstorms will slowly stall out towards the Red River Valley near morning and then sit over the region for much of Sunday. Temperatures will climb to a very humid 23°C or so on Sunday before the cold front finishes pushing through.

Behind the cold front, cooler and less humid air will begin working back into Manitoba. Sunday night will see the coolest overnight low in a while as it dips towards the low teens. With that cooler, drier air will come a northwesterly flow which will likely mean a return to smokier conditions.

Summer Warmth Under Smokey Skies for Canada Day

Brad Leave a comment

It’s safe to say that alongside all the smoke from forest fires raging across the Northern Prairies, summer has arrived. With daytime highs in the mid- to high–20’s for the coming 5 days and overnight lows similarly warm at nearly 5°C above normal, the cool weather of just under two weeks ago[1] is long gone!

Hot and increasingly humid weather is in store for the second half of the week, however temperatures will likely fall short of what their potential is given the haze and smoke that will advect over the southern half of the province from the fires to our northwest in Saskatchewan & Alberta.

Today will be a mild day with highs in the mid–20’s or so and some haze moving in. There’s a marginal chance of some isolated thundershower activity, but the haze & smoke aloft will likely keep things just cool enough that any convective activity is halted or severely limited.

The humidity will remain mild today with dew point values around 15–17°C. Expect temperatures to dip to around 16°C tonight.

Thursday and Friday will both be warm days with more noticeable humidity present. Dew point values are expected to climb into the upper teens, making it start to feel a bit swampy out there. There may be a bit of a reprieve from the smoke on Thursday, with just a bit of haze around, but it looks like more noticeable smoke will return for Friday. Both days will see highs in the mid- to upper–20’s, but with a bit of a footnote[2] that the high could be a degree or two higher or lower depending on exactly how much smoke manages to advect into the region for Friday.

Wet Weekend Ahead?

Weather models are beginning to come into agreement of a fairly significant storm system impacting the Prairies over the weekend.

GDPS 12hr. QPF valid Sunday Morning
The GDPS is forecasting a wide swath of rainfall across the Southern Prairies on Saturday night.

It’s still early to say, but it looks like there’s the potential for elevated convection on Saturday night, perhaps bringing some night-time thunderstorm activity to Winnipeg, and Sunday looks like it may bring a few showers to the region with a bit of remnant instability. We’ll keep tabs on this system as we head towards the weekend and have an update in Friday morning’s blog post!

  1. Overnight lows dipped to just 4.6°C on the morning of June 18th!  ↩
  2. Note: not an actual footnote.  ↩
Smoke over SK & MB - June 28, 2015

Smoky with a Risk of Thunderstorms

Scott Leave a comment

This week will start out with hazy skies from forest fires burning over Northern Saskatchewan and Alberta. There will also be a risk of thunderstorms today as a cold front moves through southern Manitoba.

Monday

Today will feature hazy skies, as extensive smoke from northern Saskatchewan/Alberta continues to pour south-eastward into southern Manitoba. The smoke will likely hold down high temperatures to the mid twenties, when they would otherwise be in the upper twenties. Despite the cooler temperatures, it is still expected that storms will develop along a cold front ahead of an incoming upper disturbance. At this point it appears that storms will be strong to marginally severe, with the highest potential for severe storms being in south-eastern Manitoba. The main threat with storms tomorrow will be large hail, although gusty winds are also possible. The main uncertainty surrounding tomorrow’s storm threat is how much the smoke will affect atmospheric (in)stability. If smoke is less extensive than expected, storms could potentially be stronger due to extra daytime heating.

Tuesday

Tuesday will be a nice day, with temperatures in the mid twenties under mainly sunny skies and light winds. There may still be some lingering smoke, but it shouldn’t be as extensive as earlier in the week. No precipitation is expected.

Wednesday

Wednesday will be another pleasant day in southern Manitoba. Temperatures will be in the mid to upper twenties under mainly sunny skies. Winds will be light once again and there is only a slim chance of showers.

Long Range

The medium-term forecast suggests we’ll generally see normal to above-normal weather for the next week or so. Beyond that it appears there may be slightly more unsettled conditions as we see more frequent chances for stronger weather systems passing through the region.

Warm Weekend Brings Severe Thunderstorm Threat

Brad 1 Comment

True summer warmth is on the way for Winnipeg with temperatures soaring into the upper 20’s and overnight lows in the mid- to upper-teens. However, alongside the warmer weather, multiple threats for severe thunderstorms will return to the region.

Friday

Friday
29°C / 17°C
Partly cloudy, chance of a thunderstorm

Today will be a very warm day with temperatures climbing into the upper 20’s and light winds. Skies will start off sunny, and then we’ll see some afternoon cloudiness develop over the valley alongside some scattered thunderstorms. There’s little organizational feature, so it will be rather hit and miss as to whether you see a thunderstorm where you are or not.

Further north and west, there will be a slight risk of severe thunderstorms. MUCAPE (a measure of instability) values of 1000–1500 J/kg coupled with 25 kt of bulk shear will be substantial enough to support the organization of severe thunderstorms. A mid-level disturbance will slump to the southeast into Parkland Manitoba and the Interlake by early- to mid-afternoon and provide a focus and trigger for thunderstorm initiation.

AWM Day 1 Convective Outlook valid Friday June 26, 2015
A slight risk of severe thunderstorms exists today over southwest Manitoba into the Interlake region.

Severe thunderstorms are not expected widespread, but isolated severe cells are possible. Over the western sections of the slight risk area, large hail and heavy rain will be the primary threats. Those threats also exist further east in the slight risk area – mainly along the Red River Valley escarpment into the Interlake – there will also be a slight chance for funnel clouds or weak landspout tornadoes due to the additional “spin” provided by a shortwave moving through.

Temperatures will remain quite warm overnight with lows dipping to just around 16 or 17°C.

Saturday

Saturday
27°C / 14°C
Mixed skies; risk of a severe thunderstorm

Saturday will see a severe thunderstorm threat return to Winnipeg as more humidity pushes northwards ahead of a significant shortwave and associated trough line approaching from Saskatchewan. Dew point values are expected to climb into the upper teens producing MLCAPE values over 2000 J/kg. Strongly veering wind profiles coupled with over 40 kt of bulk shear will result in a moderate severe thunderstorm threat. While some models show surefire convection, there may be issues with a capping inversion depending on exactly how warm it’s able to get.

AWM Day 2 Convective Outlook valid Saturday June 27, 2015
A slight risk of severe thunderstorms exists on Saturday through the Red River Valley, Interlake and eastwards to the Ontario border.
An updated convective outlook graphic is available in the comments below.

Given the uncertainty, a slight risk for severe thunderstorms exists on Saturday through the Interlake into the Red River Valley. As the issues with the capping inversion become clearer, the threat may be upgraded to a moderate risk.

The primary threat with storms on Saturday would be damaging hail, strong winds and torrential downpours. Shear profiles are supportive of supercells, and while it’s not considered a significant likelihood, it’s important to remember that supercell thunderstorms can produce tornadoes.

Regarding non-thunderstorm weather on Saturday, temperatures will climb into the upper 20’s which will feel more like the low- to mid–30’s with the increased humidity. The winds will be out of the south at around 20km/h. Skies should clear on Saturday night as temperatures drop to the mid-teens.

Sunday

Sunday
28°C / 15°C
Mainly sunny

Sunday will finally see both warm temperatures and quiet weather. Temperatures will climb back into the upper 20’s with winds out of the north at around 15–25km/h. With those northerly winds, the humidity will be quite a bit more comfortable than on Saturday.

Some thunderstorm activity will occur in Manitoba on Sunday, but it will most likely be constrained east of Lake Winnipeg & down into the northern Whiteshell. The thunderstorm activity does not look like it has an organized severe threat.

Expect temperatures to dip back to the mid-teens on Sunday night.