Winnipeg will see a chance for some thunderstorm activity this afternoon with the passage of a weak cold front late today, but today’s unsettled weather will lead into a beautiful August weekend.
Friday
30°C / 17°C
Afternoon cloud; late-day thunderstorm likely
Saturday
27°C / 12°C
Partly cloudy
Sunday
28°C / 18°C
Partly cloudy; risk of showers or thunderstorms late in the day
Thunderstorms Possible in Muggy Airmass
Today will be a hot and muggy day. Temperatures will climb to the 30°C mark by the afternoon with dewpoint values topping out around 20°C, making it feel like the upper 30’s. Winds will be light out of the south.
Things will change as a cold front slumping southwards through the Interlake pushes into the Red River Valley late in the day. Scattered thunderstorms are likely along the front late in the day into the evening; in general the storms will be non-severe, however an isolated severe storm with strong winds or large hail may be possible.
A pleasant night will follow the passage of the cold front; the temperature will drop to around 14°C with clear skies.
Beautiful Weekend Ahead
Saturday and Sunday will be beautiful days for late August with dry weather and warm temperatures in store. Things might take a turn towards the unsettled late in the day on Sunday, although there’s some disagreement on the timing of when the next significant system impacts Winnipeg.
Saturday will be partly cloudy with light northeasterly winds as a ridge of high pressure moves across southern Manitoba. Temperatures will top out around 27°C and drop into the low teens – around 12°C – on Saturday night. Humidity levels will be more comfortable as drier air moves into the province behind Friday’s cold front.
Sunday will be another partly cloudy day with a high near 28°C. More cloud will likely work its way into Winnipeg later in the day ahead of the next low pressure system trundling our way.
There’s fair disagreement on the timing of this next system; the US models bring it through the Red River Valley on Sunday evening, while Canadian models move the system slower and don’t bring it into our region until Monday afternoon. Either way, there’s fairly good agreement that this system will bring a broad area of showers and thunderstorms with it. Depending on the timing and evolution of the system, we may end up with the potential for some severe thunderstorm activity.
Sunday’s weather will be something we’ll keep monitoring and provide an update later in the weekend looking at how this upcoming system is evolving.
The hottest weather of the year will give way to a return to unsettled conditions with multiple low pressure systems tracking through the province over the next week.
Temperatures will soar over the next few days as very warm air moves into the region alongside increasing dew points, resulting in some blisteringly hot weather. The decidedly summer-like weather will be short-lived, though, as a system moving through on Saturday puts southern Manitoba back into an unsettled pattern with multiple follow-up low pressure systems expected over the coming week.
Dew point values are forecast to climb over 20°C today (shown in orange colors).
Start the Warm-Up
Friday
28°C / 19°C
Hot and increasingly muggy. Slight chance of a shower or thunderstorm.
Today will mark the start of a significant warm-up. Southerly winds at 20-30km/h will help our dew point rise through the day to around 20°C, making it feel fairly muggy outside by the end of the day. The temperature will climb to around 28°C, which will feel more like 35 or 36 with the humidity factored in.
There will be a very slight chance of a shower midday or early in the afternoon. The evening looks quite nice at this point, and then Winnipeg & the Red River Valley will see a chance of a thunderstorm overnight. The low will be around 19 or 20°C.
AWM thunderstorm outlook for July 4th into the 5th, 2014.
UPDATE: A discussion on today/tonight’s thunderstorm potential is available below in the comments.
Saturday: Sweltering Heat and Severe Storms
Saturday
32°C / 18°C
Hot and muggy. Slight risk of severe thunderstorms.
Make sure your A/C is in tip-top shape, because Saturday is going to be a scorcher. Even warmer air will push into the region on Friday night, making high temperatures on Saturday soar all the way into the low 30’s. Here in Winnipeg, the daytime high should sit somewhere close to 32°C. When combined with the humidity, it will feel more like 40 or 41 outside, easily making it the warmest day of the year so far. Winds will be fairly light out of the south shifting to westerly at around 20km/h.
AWM thunderstorm outlook for July 5th into the 6th, 2014.
UPDATE: A discussion on today/tonight’s thunderstorm potential is available below in the comments.
All that heat and humidity does mean there will be a risk for severe thunderstorms. At this point it there’s still a fair amount of uncertainty as to whether or not storms will develop or not, so we’re going to wait until tomorrow to do a detailed thunderstorm outlook. In general, most storm parameters look quite favourable, but a strong capping inversion will be in place in the low-levels. Two potential triggers will need to be watched:
A weak cold front slumping southwards through the day – I don’t think this is very likely to trigger much.
A shortwave and associated jet maximum moving along the international border overnight.
If any thunderstorms develop, they will likely be severe. The main threats will be torrential rain[1], large hail and strong winds. Right now it seems most likely that thunderstorms will hold off until overnight, but we’ll take a closer look later today and add a thunderstorm outlook to this post.
Sunday Showers?
Sunday
26°C / 15°C
Chance of showers or thunderstorms.
Sunday will be a generally unsettled day with a risk of showers or thunderstorms as a cold front pushes across the province. Winds will pick up out of the west to around 40-50km/h as we head to a high of around 26°C. Severe weather is not expected right now, but the showers or thunderstorms moving through the region could be heavy/strong.
Winds will stay strong through the night as temperatures dip to the mid-teens.
Unsettled Week Ahead
There will be plenty of chances for showers or thunderstorms in the coming week. Right now it looks like the best chances are Monday, Tuesday night, then Friday. Highs will likely be in the mid-20’s with lows in the mid-teens and the humidity will remain at more comfortable levels.
Temperatures will be on their way up as a warmer, more humid air mass begins moving in from the south, but ample cloud will keep sunshine relegated to “rare resource” status.
The cooler weather of the first half of the week is on it’s way out as a broad trough pushes across the Prairies. A southerly flow will spread through Saskatchewan and Manitoba today which will begin tapping into both warmer and more humid air pushing northwards through the American Plains.
The Canadian forecast model shows the muggy air expected to move in by Friday.
The warmer and more humid air will, unfortunately, also result in more unsettled weather bringing plenty of cloud to the region. Multiple disturbances tracking into the region by week’s end will also result in the return of thunderstorm activity.
Wednesday
20°C / 14°C
Mostly cloudy with a chance of midday showers. Clearing overnight.
Thursday
25°C / 16°C
Increasing cloudiness in the afternoon. Chance of showers overnight.
Friday
26°C / 17°C
Mainly cloudy with showers or thunderstorms.
Another Cool, Cloudy Day
Today will be cool and mostly cloudy through much of the Red River Valley. A few sunny breaks may develop this morning, however with daytime heating more clouds will likely be generated to take their place. There is a slight chance of some showers in Winnipeg and the rest of the Red River Valley beginning late this morning through the afternoon, but anything that develops looks to be fairly light. The high today will be around 5°C below normal at 20°C.[1] Winds will gradually shift from northeasterly this morning to southeasterly by the end of the day, remaining relatively light throughout.
Skies should clear out a fair amount on Wednesday night as temperatures dip to a low near 14°C.
Warmer, Unsettled Weather Moves In
Thursday will be the transition day for the Red River Valley into a warmer, more humid air mass. The day will likely start off mostly sunny – or perhaps a high overcast – with winds out of the southeast increasing to 20-30km/h. The temperature should reach around 26°C, however more notable will the rising dew point[2] which should reach around 17°C by the end of the day. While not too high, the extra humidity will definitely be noticeable by the evening.
Total precipitation forecast by the GDPS for Thursday evening to Friday morning.
In addition to the rising humidity, cloud cover will spread into the Red River Valley from as a trough works its way into southwestern Manitoba. Showers and thunderstorms will be likely over southeastern Saskatchewan and southwestern Manitoba late in the afternoon and into the evening. Although it appears that the worst – and more likely to be severe – weather will remain in Montana and North Dakota, an isolated severe thunderstorm cannot be ruled out, particularly in SE Saskatchewan.
The afternoon storm activity will weaken after sunset but likely continue through the night pushing eastwards and northwards. There will be a fairly good chance of some shower or thundershower activity tomorrow night through most of the Red River Valley; no severe weather is expected at this point. Thanks to the more humid air, the overnight low will sit around 17°C.
Stormy Friday
Friday will mark a return to wetter weather as a low pressure system lifts northwards out of North Dakota through the Red River Valley, bringing with it a surge of warm, muggy air. Temperatures will climb into the high 20’s – likely around 26 or 27°C – while the dew point rises to around 21 or 22°C, making it feel very muggy.
Thursday’s overnight activity may be lingering in the morning, but it looks quite likely that things will become unstable late in the morning or early in the afternoon again, bringing more shower and thunderstorm activity. It’s still a little early to make very specific predictions, but if things pan out the way it looks now, there would be a very slight chance of severe thunderstorms in the Red River Valley with the main threats being torrential rain causing flash flooding[3] and large hail. We’ll be refining our convective outlook closer to the event since small changes between now and then – particularly with the night-time storms – can dramatically alter the forecast.
Friday night will be cloudier than not with an overnight low of 17°C. It looks fairly likely that a line of thunderstorms will develop through North Dakota along a weak cold front and track northeastwards through the overnight period. At this point it looks like that system will continue to bring a risk of thunderstorms to the Red River Valley through much of the night, but the best support for severe weather looks to remain in North Dakota/Minnesota.
Unsettled Weekend
The unsettled weather will continue through the weekend as yet another upper low begins building into the Prairies (the third in as many weeks). Saturday will likely see showers and thundershowers to the east and north of the Red River Valley to start the day. Much of the day may end up being fairly pleasant, so if that materializes get out and enjoy it!
A shortwave is forecast to move across the province on Saturday night, likely bringing another outbreak of thunderstorm activity. Severe weather may be possible.
Sunday looks to be a nice day, with the sun likely finally making an appearance and a high near the mid-20’s. The humid air should be off into Ontario by Sunday, so it will likely be quite a comfortable afternoon here in the Red River Valley.
Unless a little more sun develops, then we may see 21 or even 22°C before showers take over. ↩
Dew point is a measure of how much water is in the air. Compared to relative humidity, it’s a more consistent representation of how humid it is. ↩
Which wouldn’t be particularly difficult, given the high water levels already in place. ↩
Slightly cooler weather will move in this weekend behind a low pressure system forecast to move through tonight and tomorrow. In addition to the cooler temperatures, this system will bring a chance of rain and thunderstorms to the Red River Valley.
Tonight & Tomorrow
Friday 27°C / 18°C Increasingly cloudy; risk of a thunderstorm late in the afternoon into the evening. Humid.
We’ll see gradually increasing cloud today as the surface trough associated with a low pressure system pushing into the northern Interlake approaches. There may be some ongoing thunderstorm activity along the trough this morning as it pushes through SW Manitoba and that threat will move eastwards into the Red River Valley by the late afternoon or early evening. A southerly wind ahead of the trough coupled with a capping inversion will draw moisture northwards once again and trap it near the surface, making for another hot, sticky day here in Winnipeg. Our high temperature will only climb to around 27 or 28°C, though, thanks to the increasing cloudiness through the day. That hot, humid weather will bring the threat for thunderstorms – potentially severe – late in the afternoon into the evening hours. At this point, it seems like somewhere between 8PM and 11PM seems like the most likely time for seeing any potential storm activity. After that we’ll see our temperature drop to around 18°C under a partly cloudy sky.
Saturday 25°C / 12°C Becoming cloudy, good chance of showers or thundershowers. Humid again.
Saturday will be another humid day as we remain in the moist air mass ahead of the cold front. We’ll see a fairly good chance of showers or thundershowers beginning later in the morning and through the afternoon. Skies will start off as a mix of sun and cloud but should become fairly cloudy in the afternoon as things become more unstable with the approaching cold front. We’ll see a high of around 25°C which will mark the last day in our hot, muggy air mass. The threat for showers or thunderstorms will persist until the cold front passes.
500mb winds forecast by the NAM show an intense upper-level low pushing into Southern Manitoba which may be the catalyst for showers and thunderstorms on Saturday afternoon and evening.
The cold front will push through overnight, bringing northwesterly winds that will clear out much of the moisture and drop us to a comparatively cool 12°C for an overnight low with clearing skies.
Sunday & Holiday Monday
Sunday 23°C / 8°C Sunny. Cooler and much less humid.
Monday 25°C / 13°C Sunny and warm.
Sunday and Labour Day Monday look absolutely beautiful. Sunday will be slightly cool with a high of only around 23°C and lead into a chilly night with a low dropping into the single digits bottoming out around 8°C. The heat starts to return on Monday with sunny skies continuing as we climb to a mild 25°C.
The Trend Next Week
Looking further into the week, it looks fairly nice overall as the upper ridge begins rebounding back northwards into the Prairies. Highs will push back into the upper 20’s with humidity staying fairly low until late in the week. Things look fairly dry through the first half of the week, with a few weak disturbances bringing the threat for isolated-to-scattered thunderstorms late in the week. For the most part, though, it looks to be a beautiful, warm week. Summer may be late, but it doesn’t look like it’s going anywhere soon!
