Tag: Thunderstorms

Stormier Weather Ahead

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Rainfall expected on Monday night.

Rainfall expected on Monday night from the RDPS.

Unsettled weather will mark the start of the week as multiple disturbances move through Southern Manitoba in quick succession. A weak trough will push across the Red River Valley late this afternoon and through the early evening associated with a low pressure system moving through Northern Manitoba. That will quickly be followed up by a disturbance moving out of North Dakota through Southern Manitoba as well.

Today

Monday

28°C
Mainly sunny.
Monday Night

18°C
Increasing cloud. Rain with thunderstorms likely overnight.

Most of the day will be pleasant today as mainly sunny skies dominate and the temperature climbs to around 28°C. Clouds will develop a little later in the day as the trough line approaches and we’ll see a slight risk of a thunderstorm in the evening. At the same time as our slight risk of a thunderstorm, a more organized area of thunderstorms will be developing in North Dakota supported by an upper-level disturbance. This area of storms looks to expand into an area of rain with a few embedded thunderstorms as it moves northeastwards into Southern Manitoba and will likely bring rain with a decent chance of some storms through the overnight period to the Red River Valley. The rain could be quite heavy at times, with accumulations potentially reaching the 2” (50mm) mark. There’s still a little disagreement in the models regarding the development of this system, so we’ll be sure to keep an eye out in case it looks like this rain won’t develop. With how things look now, it seems likely that the rain would reach Winnipeg late overnight and move off by mid-day on Tuesday.

Tuesday

Tuesday

23°C / 13°C
Showers tapering off by the afternoon then clearing.

We’ll see a cloudy start to the day with showers likely as long as the convection in North Dakota develops as expected. They could still be quite heavy at times in the morning, so we’ll probably be off to a very wet start to the day. Things should taper off as the main support for the rain pushes into Northern Ontario by the early afternoon hours and then we’ll see sunshine work it’s way out. A few hours of afternoon sunshine should help push our temperature up to around 23°C by late afternoon. On Tuesday night we’ll see mainly clear skies with temperatures dipping to 13°C as we move into a slightly cooler air mass.

Wednesday

Wednesday

28°C / 15°C
Sunny.

Wednesday will mark the turnaround back into a hot weather regime. Sunny skies will dominate as we climb to a high of 28°C with fairly light winds. The sunny, warm weather will be thanks to a upper-level ridge building into the Prairies. We’ll drop to a low around 15°C on Wednesday night under clear skies.

Rest of the Week

The rest of the week will be increasingly hot as a southerly flow redevelops over the eastern Prairies and begins bringing Gulf moisture northwards into the region again. This will be marked by daytime highs near 30°C and increasingly humid air building into the Red River Valley. We’ll have more details on Wednesday, but at this point it looks like the second half of the week and the weekend will be marked by hot, humid sunny weather with a low risk of seeing any stormy weather.

Beautiful Weather Ahead; Summary of 2013 So Far

Brad Leave a comment

We’ll see a beautiful second half to the week as an upper ridge continues to dominate the Eastern Prairies bringing more heat and humidity to Southern Manitoba with daytime highs climbing to (or just over) 30°C.

Wednesday

31°C / 19°C
Mainly sunny.
Thursday

30°C / 18°C
Mainly Sunny. Becoming humid.
Friday

30°C / 18°C
Mix of sun and clouds. Humid. Risk of showers or thunderstorms.

The next couple days will bring mainly sunny skies with highs just over 30°C. Winds will remain fairly light and comfortable dew points will make for perfect summer weather. By Thursday afternoon, dew points will begin to climb ahead of an approaching trough line making things start to feel a little sticky.

On Friday, we’ll see continued hot weather however the upper ridge will have moved off and we’ll see a trough line pushing across Southern Manitoba. Depending on how things develop on Thursday night in Saskatchewan, we may see a few dying showers or thundershowers on Friday morning, but the main threat for any storm activity should hold off until the afternoon. Moisture pooling along the trough will push the dew points towards 20°C, making it feel very humid and closer to 37 or 38°C than the high of 30°C. There’s a decent chance we’ll see some thunderstorms on Friday afternoon develop along the trough line, a few of which may be able to become severe. MLCAPE values from 800–1000J/kg are fairly low, however SBCAPE values look to sit between 1500–2000J/kg; if a storm is able to get organized enough to really tap the surface moisture the main threats would likely be heavy rain given the ample moisture available coupled with fairly weak bulk shear and slow storm motion. We’ll have a more comprehensive look at the severe weather threat for Friday in the next blog post. Enjoy that summer weather!

A Look at 2013 So Far

We’ve made it half-way through 2013! This year has started in sharp contrast to last year where unprecedented heat swept over North America very early in the year, leading to a record-breaking start to spring and summer that fast-tracked 2012 to one of the top–5 hottest years ever for Winnipeg. 2013 has seen a painfully slow start to the summer weather as the icy grip of winter hung on for an inordinately long time leading to one of the latest snow melt dates ever record in the Red River Valley.

2013 Monthly Temperatures

Monthly average temperatures from the Winnipeg Richardson International Airport for 2013. The dashed line represents the 1981–2010 average.

Looking at monthly average temperatures, perhaps most interesting is how “normal” this year actually has been. January and February ended up almost perfectly seasonal, as have May and June. March and April, however, clearly show the impact of the prolonged cold and snow pack. April finished with a monthly average temperature of –2.1°C which was 6.6°C below normal and a whopping 7.9°C below 2012.

Jan Feb Mar Apr May Jun
2012 –10.8 –9.8 2.2 5.8 12.2 17.7
2013 –16.7 –14.0 –8.0 –2.1 11.1 17.5
Average –16.4 –13.5 –5.8 4.5 11.4 16.9
Table of average monthly temperatures from the Winnipeg Richardson International Airport for 2013. Temperatures are in °C. Average is for the period 1981-2010.

Looking at the year-to-date average temperature, things look about as we would expect. We started off near-seasonal with things falling a little below-normal through our cold spell in the spring which has been maintained as we’ve seen temperatures climbing back to seasonal with no above-seasonal weather. We’re a good deal cooler so far than last year, but that’s expected given the start we had in 2012.

2013 YTD Average Temperature

Year-to-date average temperatures from the Winnipeg Richardson International Airport for 2013. The dashed line represents the 1981–2010 average.

Despite the spring that would never end, this year is shaping up to be surprisingly seasonal! The 30°C weather recently is certainly helping me forget the snow that stuck around for so long…

Jan Feb Mar Apr May Jun
2012 –10.8 –10.3 –6.1 –3.2 –0.1 2.9
2013 –16.7 –15.3 –12.9 –10.2 –5.9 –2.0
Average –16.4 –14.9 –11.9 –7.8 –4.0 –0.5
Table of year-to-date average temperatures from the Winnipeg Richardson International Airport for 2013. Temperatures are in °C. Average is for the period 1981-2010.

Precipitation so far this year at the airport has been near-normal and slightly less than last year. I’d just like to make a comment that this spring/summer, especially over the past month, has been extremely wet of portions of the Red River Valley. This season has had an abnormally high number of slow-moving thunderstorms that has locally produced huge amounts of rainfall. Even here in Winnipeg, once some stations from other areas of the city are included, amounts of precipitation so far this year has varied by almost 8 inches!

2013 YTD Precipitation for Winnipeg

Table of year-to-date precipitation from the Winnipeg Richardson International Airport & Rob’s Obs unofficial observing site in Charleswood for 2013. Average is for the period 1981–2010.

The observations from Rob’s Obs include two significant precipitation events that only part of the city saw: the first is a back building thunderstorm that brought over 75mm of rain to the southwest portion of the city as well as multiple showers that passed over western portions of the city last week that gave another 20mm of rain to that area. As can easily be seen, while the airport is sitting at near-normal amounts of precipitation, some areas of the city are approaching twice the normal yearly amount. For some other areas in Manitoba, such as areas near Reston, MB, they’ve already received an entire year’s worth of rain over the past month, and that’s on top of the precipitation that’s fallen earlier this year. It’s been very wet in general over Southern Manitoba so far this year. Here’s the year-to-date precipitation values:

Jan Feb Mar Apr May Jun
2012 12.0 16.5 63.0 102.0 200.0 262.0
2013 30.0 38.0 57.0 90.5 159.5 222.3
2013
Rob’s Obs		 3.0 8.6 24.8 66.9 185.6 441.6
Average 19.1 33.6 59.0 89.1 149.0 237.8
Year-to-date precipitaiton from the Winnipeg Richardson International Airport & a Charleswood observation site for 2013. Precipitation amounts are in mm. The dashed line represents the 1981-2010 average.

It will be interesting to see how the remainder of the year plays out. While 2012 started off very warm, we actually had below-normal temperatures in the second half of the year that brought us closer to seasonal – although it was still an exceptionally warm year – than it originally seemed that we would. We’ve had a cold start to the year, but we seem to finally be getting into the swing of summer and plenty of hot weather seems to be in the future as long-range models continue to support/sustain a large ridge over the Rockies.

A Brief Reprieve From Storms

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It’s been a wet and wild week in Southern Manitoba as muttiple rounds of thunderstorms have pummeled the region with heavy rain. On Thursday, 75mm of rain fell in southwest Winnipeg, causing substantial amounts of flooding to neighborhoods, schools and retail locations. On Friday night a area of heavy rain and thunderstorms pushed into Western Manitoba bringing as much as 175–200mm of rain to some regions in the southwestern portion of the province. The town of Reston, MB has declared a state of emergency after about 7.5” of rain fell on Friday night (~ 190mm). Approximately 2/3rds of the town’s population has been affected by the flood waters that engulfed the town as it’s drainage system simply could not keep up with the intense downpour.

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The village of Reston, MB has declared a state of emergency after heavy rain caused significant flooding. Photo credit: Jillian Coubrough/CBC

On Saturday evening, an intense line of thunderstorms developed along the western escarpment of the Red River Valley and remained stationary for almost 3 hours. The hardest-hit areas just west and northwest of Portage la Prairie where – as evidenced by RADAR-estimated rainfall accumulations and a report from the town of Westbourne, MB – as much as 225mm (9”) of rain fell. On Sunday, an area of rain and thunderstorms lifting northwards through western Manitboba brought another 50–75mm of rain. This additional rainfall in an already waterlogged region has brought more overland flooding and caused mutliple highways to be closed near Riding Mountain National Park.

But a reprieve is in store for Southern Manitoba as the upper low that has been drawing a moist, unstable air mass from the Gulf of Mexico and brought catastrophic flooding to Calgary and southwest Alberta finally moves out of the region. This will allow a slightly drier, more stable air mass to move into Southern Manitoba on Monday. Things are not meant to last, though, as the heat and moisture is set to return on Tuesday as another system pushes into the Prairies and brings the storm threat back.

The Next Few Days

Monday

26°C / 15°C
Mainly Sunny
Tuesday

29°C / 18°C
Hot and humid. Thunderstorms possible in the evening & overnight.
Wednesday

26°C / 15°C
Mostly cloudy; showers likely.

We’ll see a beautiful day today with mainly sunny skies. A westerly wind will bring in slightly dryer air which will help things feel a little more comfortable as we head to a high of around 26°C. Skies will be mainly clear tonight as we drop to around 15°C.

Heat and humidity will begin to build in on Tuesday as a southeasterly wind develops and begins drawing Gulf moisture northwards again. Dewpoints should climb back towards 19–20°C as our temperature soars into the high 20’s. While the high will top out around 28 or 29°C, when combined with the humidity it will feel much closer to 35°C out there. An approaching trough will push into SW Manitoba through the afternoon and move into the Red River Valley in the evening.

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CAPE values are expected to climb towards 2500–3000J/kg in southwestern Manitoba on Tuesday.

Thunderstorms should fire along this feature in the afternoon and pretty much every single thunderstorm parameter looks fantastic. CAPEs are expected to exceed 2500J/kg, LI values are expected to be beween –5 and –10°C, surface dewpoints should pool to around 20°C along the trough and a decent shear profile will be in place. It looks likely that any storms that develop will likely have the potential to become severe with threats of large hail, torrential rain and tornadoes. The storms will likely grow into a line of storms as they slowly progress eastwards towards the Red River Valley, with a good chance of heavy showers or thunderstorms in the late evening or overnight here in Winnipeg.

On Wednesday we’ll be stuck underneath a low pressure complex. The overnight convection should clear out through the morning hours then we’ll move into a mix of sun and cloud with scattered showers through southern Manitoba. We’ll see a high climb into the mid–20’s and clearing skies overnight with a low near 15°C.

Rest of the Week

It looks like we’ll finally move into a dryer pattern for at least a few days as a weak upper ridge pushes into the Prairies. Temperatures will be mid–20’s with significantly dryer air in place making for some pleasant, warm and comfortable summer weather. A few thunderstorms may be possible throughout the latter half of the week, but with less moisture available they shouldn’t produce the excessive rainfall totals we’ve seen over the past several days.

Winnipeg Hammered By Torrential Rain; Thunderstorm Threat Continues Through Weekend

Brad Leave a comment

Portions of Winnipeg experienced a tremendous amount of rainfall yesterday evening as a thunderstorm developed over the southern half of the city and sat in the same spot for over an hour. While many areas in the city saw less than 10mm of rainfall, reports of localized flooding were numerous as rainfall rates that climbed as high as 300mm/h dumped between 50–80mm of rain over a small area of southwestern portions of the city.

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24hr. rainfall accumulations from Thursday evening. Given that we had no significant precipitation on Wednesday in Winnipeg, this is effectively the rainfall accumulations for Thursday’s thunderstorm in Winnipeg. Amounts outside Winnipeg wiil be representative of the full 24hr. period.

The storm moved into Winnipeg around 7:15PM Thursday evening as a small thunderstorm southeast of the city near Ils Des Chene moved northwestwards toward another thunderstorm stationed over Headingly that had been warned for producing heavy rainfall in that area. By 7:40PM, the storm west of the city merged into the storm inside the city and intensified. At this point, everything stopped moving.

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Flooded Roads on Sterling Lyon Parkway; Photo courtesy @shelzolkewich.

In an area roughly bounded by McGillvery Blvd., Pembina Highway and Portage Avenue, the rain simply kept coming and coming. Numerous reports started showing up under #MBstorm on Twitter. Early on it was clear that areas near Kenaston & the Sterling Lyon Parkway were being hit very hard with photos coming in showing flooded roads with water as much as just over a foot deep.

Reports began to come in of actual rainfall amounts, too. @robsobs, a very reliable source for rainfall data in SW Winnipeg (as well as the person who runs the excellent Rob’s Blog reported a peak rainfall rate of 300mm/h under the heaviest rainfall. Near the end of the event, he reported a total of 69mm that fell over the course of 2 hours:

In addition to roads being flooded, there were numerous reports of ditches & pools overflowing. The heavy rainfall also impacted one of Winnipeg’s newest and largest stores: IKEA. The IKEA on Kenaston was evacuated yesterday evening as water began pouring into the main floor of the store:

It may not have seemed like a day where severe weather was likely since skies were mostly cloudy through the day and temperatures climbed only into the mid–20’s. There was plenty of moisture building into the region, though, and many of the conditions we look for with convection were in place.

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Another shot of the flooding on Sterling Lyon Parkway. Photo by @tracylkj.

While we didn’t have enough sunshine to get the storms started, a strengthening trough of low pressure laying across the Red River Valley managed to initiate storms which then fed off the abundant low-level moisture and produced just one significant storm that impacted Headingly and Winnipeg. The Winnipeg region was included in our Slight Risk area on Thursday morning.

Friday


26°C / 16°C
A mix of sun and cloud. Small chance of thunderstorms in the afternoon & overnight periods.

Today will be a warm, humid day with temperatures climbing once again to around 25–26°C and with dew points hovering in the 18–20°C range. Once again we’ll see a risk of thunderstorms develop in the afternoon as the atmosphere destabilizes. The key ingredient for today’s threat will be our daytime high. If dew points stay close to 19 or 20°C and we can get to 27°C, we’ll see a much greater chance of thunderstorms than if the dew point is closer to 18°C and we stay near 25 or 26°C. Should storms develop in the Red River Valley, they’ll see a potent environment to develop in with substantial instability aloft and CAPE values of nearly 2500J/kg. The big limiting factor in their development will be the near absence of shear. The wind will be extremely light below 500mb which will make it very difficult for storms to develop the structure required to make them long-lasting entities. As such, any storms that develop in the afternoon will likely be pulse-type storms whose main threats would be heavy rain and/or large hail.

By the evening another round of elevated convection looks to fire up and lift northwards. It may end up west of, over, or east of the Red River Valley. It’s simply too early to tell at this point. We’ll be sure to update our thoughts below as things become more clear. We’ll head to an overnight low of around 16°C tonight.

The Weekend

Saturday

23°C / 14°C
A mix of sun and cloud. Chance of a shower.
Sunday

23°C / 12°C
Mainly cloudy. Showers or thunderstorms likely.

We’ll see the main upper low that’s been pulling moisture northwards and setting up our instability begin to work it’s way eastwards through the Prairies this weekend. Saturday actually looks to be a fairly nice day; dew points will drop towards the mid-teens and we’ll see a slightly cooler high of around 23°C under a mixed sky. There will be a slight chance of showers as a trough swings through, but things seem stable enough that they would be fairly scattered and light. Saturday night will see some cloudy periods with a low of around 14°C.

On Sunday we’ll likely see showers and thunderstorms as the upper low moves over us. Things will destabilize under the upper low early in the day and the relatively warm, moist air mass should have little trouble supplying enough instability and moisture to get things going. No severe weather is expected. Sunday will mark the return of dryer air into the Red River Valley.