Tag: Colorado Low

High waves due to the strong winds in Gimli.

Colorado Low Slams Southern Manitoba Over May Long Weekend

Brad 4 Comments

Southern Manitoba was slammed by a powerful Colorado Low this past weekend that brought a wide array of severe weather to the province. Between heavy rain, ice pellets, snow and very strong winds, the storm wreaked havoc on the regions infrastructure with widespread damage to trees, power outages, closed highways, structural damage and overland flooding.

The system was, fortunately, well forecast by Environment Canada with fairly accurate forecasts issued in the days leading up to it alongside special weather statements addressing the numerous impacts the system may have on the region.

Significant Rainfall Began Saturday Afternoon

Fortunately, the weather was able to hold for much of Saturday. Temperatures climbed into the low 20’s across Southern Manitoba with increasing cloudiness. Rain & thunderstorms developed through North Dakota & Montana and lifted northwards through the day, first spreading into SW Manitoba in the afternoon and then eastwards and northwards through the evening and overnight period.

Twitter user @AxeHaft snapped this picture of flooded farmland near Altona, MB.
Acres of flooded farmland between Winnipeg & Portage la Prairie. Photo via @CTVNewsBen.
Overland flooding near Oak Bluff, MB. Photo via @AnitaAnseeuw.
Overland flooding at the cottages in Albert Beach, MB. Photo via @lovestormsMB.

Some of the hardest hit regions were in SW Manitoba where hours of training thunderstorms & convective showers produced moderate to heavy rain. The Melita region was hit the hardest with 72mm of the grand total 90mm of rain falling by midnight on Saturday night. For areas further east, through, much of the rain fell through Saturday night & Sunday. Total rainfall amounts for Saturday and Sunday combined were:

Rainfall Totals for May 16–17, 2015 – Environment Canada & Manitoba Agriculture (*) Stations
Location Rainfall Total (mm)
Melita 90
Bede* 83
Gretna 63
Carman 60
Deloraine* 57
Deerwood 55
Morden 51
Kleefeld 48
Reston* 48
Dugald* 45
Pilot Mound 44
Emerson 43
Pierson* 43
Letellier* 41
Winnipeg (Forks) 41
Portage East* 40
Portage Southport 40
Woodlands* 38
Oak Point 37
McCreary 36
Winnipeg Airport 36
Pinawa 36
Great Falls 34
Carberry 33
Sprague 32
Virden* 30
Brandon 29
Fisher Branch 29
Cypress River 28
Glenboro* 27
St. Pierre* 25
Wasagaming 24
Dauphin 22
Teulon* 21
Killarney* 20
Wawanesa* 20
Minnedosa* 17
Eriksdale* 16
Roblin 16
Souris* 15
Berens River 14

This rainfall is in addition to the 25–50mm of rain many areas in the region saw just a couple days prior to this storm. There were several areas that saw significant overland flooding due to the sheer quantity of water that fell over the short time frame.

Additionally, there were reports of sewage back-up and spotty basement flooding across Winnipeg.

Then Came the Wind

Sunday is where the brunt of the storm impact was felt. As the main low pressure centre lifted northwards into the Dakotas, a strong 1037mb high pressure centre was building into the central Prairies.

Surface analysis for early Sunday morning.
This surface analysis for early Sunday morning shows the strong low in the Dakotas and the strong high building into the central Prairies.

These systems produced a strong pressure gradient over southern Manitoba and produced some of the strongest, longest-duration winds for a major storm in recent memory. Winds were in excess of 50km/h for 20 hours in Winnipeg with a 6-hour stretch beginning late Sunday with winds of 60km/h or greater. Very strong gusts also accompanied the winds with Winnipeg recording the highest wind gust at 93km/h:

Peak Wind Gusts for May 17, 2015
Location Peak Wind (km/h) Time (CDT)
Winnipeg 93 6:44PM
Gimli Harbour 89 9:38PM
Carberry 87 4:57PM
Brandon 83 10:00AM
Kleefeld 81 4:14PM
Cypress River 81 5:01PM
Pilot Mound 81 2:45PM
Gretna 81 2:28PM
Melita 80 6:11PM
Emerson 80 4:21PM
Gimli 80 4:21PM
Porgae la Prairie 80 4:51PM

The winds may have been the most significant impact from this storm. The strong winds resulted in havoc on the highways, property damage, hundreds of downed trees, and widespread power outages. The strong winds also produced significant wave action on Lake Winnipeg and some overland flooding as rising lake levels resulted in the lake overspilling its banks and pushing inland in some locations.

High waves due to the strong winds associated with this weekend’s Colorado Low in Gimli, MB. Photo via @OlleBear.
Large tree down in Winnipeg Beach on Spruce Ave. Photo via @SeanLedwich.
Strong winds ripped the roof off of The Bridge Church in Winnipeg, MB. Photo via @CTVNewsBen.
Photo of a downed tree in Winnipeg, MB. Photo via @mikki_co.
Large tree snapped by strong winds in Winnipeg at Corydon & Nassau. Photo via @MattCundill.
A semi-truck blown by strong winds blocking the Trans-Canada Highway into Portage la Prairie. Photo via @ctvwinnipeg.

Winds tapered off to 40 gusting 60km/h on Sunday night, but remained fairly strong until tapering off Monday afternoon.

Oh, Snow Too

If the rain and the wind wasn’t enough, cold air moving in with the high pressure system resulted in precipitation switching over to ice pellets then snow beginning over Parkland Manitoba and then spreading southeastwards through the Interlake, Red River Valley & Whiteshell through the afternoon and evening. Areas through the Interlake southwestwards towards the Melita region saw the heaviest snow, with MacGregor reporting the highest amount of snow at 15cm. Amounts of 10–15cm were seen from Arnes, on the western shores of Lake Winnipeg, through Teulon, MacGregor, Treherne and down towards Boissevain:

Snowfall Totals for May 17–18, 2015 – EC Spotters & Social Media
Location Snowfall Total (cm)
MacGregor 15
Teulon 15
Arnes 10
Boissevain 10
Treherne 10
Hollow Water FN 5
Albert Beach 5
Dauphin 5
Deloraine 5
Wasagaming 5
Winnipeg 3

In Winnipeg, we saw just a few cm of snow on Friday evening and overnight. Flurries persisted through Monday but temperatures were warm enough to prevent any more accumulation.

A damaged fence alongside substantial snow accumulation in MacGregor, MB. Photo via @JBMEquiFarms.
A broken tree sits atop a damaged structure in Dunnottar, MB amidst a fresh coat of snow. Photo via @alan_tabak.
MODIS satellite imagery showing the snow swath through the southern Interlake. Photo via @robsobs.
Substantial snow accumulation near Teulon, MB. Photo via @TrishG27.

All in all, this was certainly one of the most powerful storms Southern Manitoba has seen in a good long while. Perhaps the best thing that can be said is that at least it happened now and not a month earlier, where almost certainly it would have been a historic blizzard.

Wet Week Leads to Gradual Improvement

Brad Leave a comment

A couple more days of unsettled weather will give way to some of the warmest temperatures of the year.

The main weather story will be gradual improvement as the week progresses. Currently we’re under the influence of a broad trough of low pressure that has brought scattered showers to the Red River Valley over the past couple days.

A complicated, high-amplitude flow is developing over the eastern Prairies.
A complicated, high-amplitude flow is developing over the eastern Prairies.

Multiple bands of precipitation will be in place over Southern Manitoba today thanks to multiple disturbances and a fair amount of instability. As the upper-level flow finally organizes itself, a Colorado Low eject northeastwards on Thursday bringing potentially significant rainfall to the Red River Valley and Southeastern Manitoba. The unsettled weather will linger through Thursday night but then a weak ridge of high pressure will begin building in from the west, bringing more settled weather with relatively warm temperatures, especially compared to what we’ve been suffering through so far this spring.

Wednesday
12°C / 6°C
Mainly cloudy. Occasional showers likely.

Thursday
12°C / 4°C
Showers, possibly heavy at times. 5-15mm.

Friday
15°C / 5°C
Clearing.

Today

Today will bring mainly cloudy skies to the Red River Valley as a large low pressure complex stretching from Northern Saskatchewan to Colorado slowly begins organizing itself. More organized showers will fall through much of the day west of the Red River Valley through southwest regions and the Parkland with total accumulations around 5-10mm, but here in the valley we will likely only see scraps of elevated convective showers occasionally moving over the area.

I say likely since there is pretty high uncertainty in exactly how this system will evolve today. The band of showers to our west will slowly creep eastwards towards the RRV through the day and likely push into the western Red River Valley this afternoon. There’s a chance that it will continue pushing eastwards, and if that’s the case then we might see some more organized precipitation later in the afternoon into the evening. There’s also a very outside chance that this whole thing bumps eastwards mid-morning and we’re the ones stuck under the showers for the day.

Complicating matters will be a secondary band of precipitation that will develop this afternoon and lift northwards out of North Dakota and Minnesota. It’s currently forecast to just clip SE Manitoba, but if the upper level trough tilts a bit more, which it has been doing more than the models have been forecasting for 2 days now, that band of rain could end up inside the Red River Valley.

As a third complicating factor, there seems to be fairly unstable mid-levels over most of Southern Manitoba, so even if the precipitation stays to our west and east, there will still be a chance for some light showers zipping across the valley.

Total precipitation by Thursday evening from the RDPS. The question is will it even be close to right?
Total precipitation by Thursday evening from the RDPS. The question is will it even be close to right?

It’s a very complicated setup; most models agree that there will be rain on the western and eastern fringes of the Red River Valley with little in between[1], however slight variations in the actual positions of systems could change things quite dramatically. For that reason I’m say that there’s a good chance we’ll see occasional showers today. We may see more, we may see less, but this is a situation where trying to be any more specific than that will likely be a futile effort.

What is a little more certain is that we’ll see a high near 12°C today with light southeasterly winds.

The threat for showers will continue through the overnight period through most of the Red River Valley. We’ll drop to a low around 5 or 6°C with winds shifting around to the north.

Thursday

Thursday looks to be the most active day. A strong Colorado Low will track into Minnesota, spreading rain ahead of it into Southern Manitoba. Moderate instability aloft coupled with strong lift and enhanced convergence thanks to the deformation zone will result in showers, potentially fairly heavy at times, through much of Southern Manitoba. There may even be a very slight chance of a rumble of thunder or two.

The wet weather will likely last through much of the overnight period as well. By the end, anywhere from 5-15mm of rain seems likely over the Red River Valley; amounts will likely vary over short distances, and it’s impossible to say where will see the most rain until we’re closer to the event. I’d really love to be more specific, but with this rapidly developing, complex system, the models can be quite misleading and the best forecast will come from observing what’s actually happening and how things are developing in real time.

The high temperature on Thursday will be near 11-12°C once again, and the overnight low near 5°C.

Friday and Beyond

The weather finally looks to turn towards a more pleasant pattern for the end of the week. A cut-off cold low will spin aimlessly over the northwestern Prairies, leaving us on the warmer side of things as slightly milder air manages to work its way into the region. No substantial warm push is on the way, but with the cold air locked up well to our northwest, temperatures should manage to climb to around 15-16°C on Friday, Saturday and Sunday.

It seems quite likely that we’ll see our warmest day of the year this weekend. Currently, the warmest day we’ve had was a mere 15.1°C on April 23rd, but Saturday looks likely to beat that by a degree or so. Overnight lows are expected to sit near 5-6°C through Friday, Saturday and Sunday, which will be right around normal for this time of year.

Skies should be mainly sunny on Friday and Saturday, however we will likely see some cloud and a very slight chance of a shower on Sunday as a weak low pressure system pushes into western Manitoba.

  1. And I’m inclined to believe it given how often any sort of convective precipitation manages to end up on either side of Winnipeg.  ↩

A Glancing Blow

Brad Leave a comment

A Colorado low responsible for a tragic severe weather outbreak yesterday across the the Southern United States, and Arkansas in particular, has spread rain northwards into Southern Manitoba this morning. A decent soaking is in store today and then see a cooler, unsettled week ahead as the Colorado Low persists through much of central North America.

Monday
8°C / 0°C
Periods of rain ending by the evening. 10-15mm. Breezy.

Tuesday
10°C / 0°C
A few clouds.

Wednesday
7°C / 0°C
Showers likely.

Late last week it looked as if we were set to get as much as 25-30mm in a widespread swath through much of Southern Manitoba, however we pointed out the complexities of the setup and how minor changes in the positioning of features could cause big changes in how much precipitation is produced.

It turns out the models did fairly well with the overall picture. Thanks to a little more tilt to the upper trough and the upper low being captured a little sooner than originally forecast, the system as a whole won’t push as far northwards as it looked last week and as a result we’ll see a little less rain than it looked like then.

We’re still in for a decent soaking today, though. Periods of rain will persist through the late afternoon or early evening, and in general much of Southern Manitoba will see 10-20mm of rain. Areas further north, towards the Interlake and much of Parkland Manitoba will see in the 5-10mm range, but it does appear that, for the most part, anywhere along and south of the Trans-Canada corridor in SW Manitoba and the Red River Valley will see between 10 and 20mm with the higher amounts closer to the U.S. border. The temperature will sit around 8°C today with breezy winds out of the east at 30km/h with gusts to around 50km/h.

Total rainfall expected today across Southern Mantioba.
Total rainfall expected today across Southern Mantioba.

Near the border there’s a slight chance of accumulations creeping up towards 25mm (1”) or so, but that will depend on fairly heavy rain and some lingering rainfall a bit longer than it seems like it’s likely too. The rain will taper off by this evening and we’ll see gradual clearing through the evening. The temperature will drop to around 0°C.

Another Short-Lived Break

Tuesday looks to be a cool but pleasant day with a high temperature of around 10°C and mostly sunny skies. Temperatures will drop to around 0°C once again on Tuesday night with increasing cloudiness.

Wednesday brings back the showery weather as another shot of rainfall pushes into Southern Manitoba from east to west on the back-side of the Colorado Low. Accumulations don’t look significant at this point, perhaps 3-5mm on the high end, but it does seem like it will be a cool, dreary day with a high of only around 7°C. The showers should taper off by the evening as we drop to the freezing mark yet again, this time under cloudy skies.

Where’s Summer?

Unfortunately, not here. Below-normal temperatures are once again forecast for the 7-14 day outlook, meaning we’ll likely see high temperatures only in the high single digits or low teens for the next week or two.

But it’s gotta warm up eventually, right? Right? Here’s hoping for a big turnaround in May.

A Brief Reprieve

Brad Leave a comment

This weekend will bring a brief reprieve from the wet weather before a Colorado Low begins impacting the region for the start of next week. Temperatures will remain below normal, but we should see plenty of sunshine with just relatively light south-easterly winds.

Friday
8°C / 0°C
Mainly cloudy. Chance of showers or drizzle.

Saturday
10°C / 3°C
Partly cloudy.

Sunday
11°C / 4°C
Increasing cloud.

Today will bring mostly cloudy skies with a chance for some lingering showers or drizzle as the system that’s been impacting us over the past few days slides off into Ontario. Clouds will begin to break up a bit in the afternoon as we head towards our high of around 8°C, however it won’t be until the evening or overnight period until we see the clouds actually begin to clear out.

Saturday look like the nicest day of the next few, with more sun than cloud and a high near 10 or 11°C. The wind will be out of the southeast at around 20-30km/h, but otherwise it’ll be a pleasant – albeit cooler than normal – spring day. We’ll drop to around 2 or 3°C on Saturday night under mainly clear skies.

Sunday will herald the arrival of the next storm to impact the Prairies: a massive Colorado Low that looks to stall out over the northern Plains of the United States and absolutely smother the Prairies in precipitation.

24hr. precipitation forecast from the GDPS showing anywhere as much as 30-40mm of rain from Sunday night through Monday.
24hr. precipitation forecast from the GDPS showing anywhere as much as 30-40mm of rain from Sunday night through Monday.

This system looks to be extremely complex with multiple features interacting with each other: the Colorado Low itself, a large inverted trough that looks to develop along a north/south line through Saskatchewan, and the occlusion of the upper-level low centre that will stall the system out over the Northern Plains. Subtle variations in any one of these features can dramatically alter the weather outcome, let alone how those variations will interact with each other across these features. In addition, there will be a fairly significant high pressure system through Northern Manitoba that will surely do it’s best to inject dry air into the system and really sharpen up the northern edge of it. Needless to say, we’ll be keeping a close eye on this one and have more details on where, and how much, precipitation might actually happen in the comments below as things begin to come together.