The unsettled weather that’s been in place for the last few days will continue through the end of the week as the general instability remains in place as more weather systems push through the region.
Today will be a fairly pleasant day that’s quite similar to yesterday other than a couple degrees warmer. Temperatures should climb to around 28°C this afternoon with more clouds popping up and developing into an afternoon/evening chance of some scattered thunderstorms. Thunderstorm activity should be fairly limited as the main story will be the low pressure system that will move into Southern Manitoba overnight and will set the stage for Thursday’s weather. Expect temperatures to dip to just 19°C as increasing cloud and the humidity continue to keep temperatures warm.
Thursday Brings Heavy Rain Potential
Tomorrow may actually end up being quite a wet day as multiple models are showing a low pressure system moving through tapping into the ample moisture in the region to produce a fairly large, and intense, area of rain.
NAM Precipitable Water Forecast for 15Z Thursday July 16, 2015
The NAM (shown above) is forecasting precipitable water values as high as 1.8 to 1.9” (in the 45–50mm range) which is very high for our region. Precipitable water correlates strongly to potential rainfall amounts of storm systems[1], so it’s not unrealistic to say that rainfall totals of 1.5” to 2” (~ 35 – 50mm) are not out of the question albeit on the high end. If heavy convection were to set up, then even higher amounts would be possible. We’ll keep an eye on things and see how the storm progresses this evening; if the outlook changes much, we’ll provide an update at the bottom of this post.
So, the general forecast for Thursday would see the rain moving in overnight on Wednesday night and see the rain persisting at least until mid-day, but possibly into the late afternoon or early evening. Rainfall totals may end up being variable, but in general will likely be 20–40mm with the potential of seeing double that if system becomes vigorous enough. The high temperature will be in the 21 to 23°C range with an overnight low around 16°C. Winds will be fairly light much of the day.
Friday
The thunderstorm risk returns Friday, although it will be a fairly mild risk with just some isolated to scattered non-severe storms possible. The daytime high will sit near 26 or 27°C with light winds out of the southwest. The humidity continues to remain fairly high with dew points in the high teens. Skies will clear out Friday night as we head to a low near 15°C.
Thunderstorm rainfall totals can greatly exceed PWAT values due to the convergence of the inflow wind that can “accumulate” PWAT from areas around the storm. ↩
The first part of this week will see unsettled weather as a strong low pressure system passes to our south. This system will likely result in moderate rainfall and a risk of thunderstorms over southern Manitoba on Tuesday.
Monday
Today looks to be mainly cloudy ahead of an approaching low pressure system. There may be a few passing showers throughout the day, but no major precipitation is expected. High temperatures are expected to reach the low twenties with gusty south winds.
Tuesday
Tuesday looks quite unsettled as we sit north of a fairly strong low pressure system over the Dakotas. A warm front will likely be located over northern North Dakota, allowing for warm and potentially stormy weather just to our south. In southern Manitoba, we will remain stuck in a cool easterly flow north of the warm front. As a result of our position relative to the warm front we likely see moderate rainfall during the day with a chance of embedded thunderstorms.
The simulated RADAR reflectivity from the NAM forecast for Tuesday afternoon shows a large area of rainfall moving over Southern Manitoba.
Should the warm front move further north than expected, our risk of thunderstorms will be higher, but at this time that does not look probable. Total rainfall amounts in southern Manitoba could be in the 15-35 mm range, although it is difficult to predict this sort of system ahead of time. Higher rainfall amounts are certainly possible on a localized basis due to isolated thunderstorm activity.
Wednesday
Wednesday looks cool and cloudy as Tuesday’s system departs. We my see a few showers during the day, but in general not much precipitation is expected. The wind will be from the north at around 30 km/h.
Long Range
The long range forecast suggests we’ll see generally normal to above-normal weather through the middle of June. Numerous weak to moderate weather systems are expected to traverse the region over the next while, meaning our weather will continue to feature unsettled patches, before we return to more favourable conditions.
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.
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.
Twitter user @AxeHaft snapped this picture of flooded farmland near Altona, MB.
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.
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.
Large tree snapped by strong winds in Winnipeg at Corydon & Nassau. Photo via @MattCundill.
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.
A semi-truck blown by strong winds blocking the Trans-Canada Highway into Portage la Prairie. Photo via @ctvwinnipeg.
Photo of a downed tree in Winnipeg, MB. Photo via @mikki_co.
Strong winds ripped the roof off of The Bridge Church in Winnipeg, MB. Photo via @CTVNewsBen.
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.
Substantial snow accumulation near Teulon, MB. Photo via @TrishG27.
MODIS satellite imagery showing the snow swath through the southern Interlake. Photo via @robsobs.
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.
Winnipeg, and many other regions in the Red River Valley, received the most significant rainfall so far this year yesterday as an area of moderate rain moved into the province from North Dakota and stalled out for much of the day. Rainfall totals in most places were near 20–30mm with slightly higher amounts in the southwestern Red River Valley:
Rainfall totals for the May 14, 2015
Location
Rainfall Total (mm)
Letellier
41
Altona
37.6
Morris
34.2
Winkler
29.8
Steinbach
27.8
Winnipeg
24
Dugald
22
Elm Creek
12.6
Portage la Prairie
9.6
The Altona/Letellier areas seem to be the winners for total rainfall with almost 1.5” of rain in total. Unfortunately for farmers who are still working at getting seed into the ground, there won’t be much of a reprieve from wet weather before more rain is on the way as another major low pressure system is hot on the heels of the previous one and is set to bring a whole host of unsettled, pleasant and stormy weather for the May long weekend.
Pleasant Friday, then Downhill
Friday
18°C / 7°C
Partly Cloudy
Today will be a very pleasant day across the Red River Valley with mainly sunny skies and temperatures climbing into the high teens under partly cloudy skies. Winds will be fairly light out of the northwest. Friday night will see temperatures drop to around 7°C under clear skies. The nice weather won’t last too long, though, as a potent low pressure system moving into the Northern Plains of the United States tonight will result in cloud and some light rain spreading across Southern Manitoba early on Saturday. The heaviest rainfall will hold off until much later in the day, however, as this system will end up being strongly driven by convection.
SPC Day 3 Convective Outlook valid Saturday May 16, 2015
The SPC[1] in the US currently has a slight risk of severe thunderstorms in their outlook for Saturday scrunched right up the Canadian border. Further north in our area, it looks like an initial shot of some showers associated with elevated convection will lift through the region early in the day. Temperatures will warm towards the 20°C mark with an increasing risk of showers or thunderstorms.
Saturday
20°C / 9°C
Cloudy; scattered showers with the risk of a thunderstorm
Later in the afternoon, best indications at this point are that an area of thunderstorms will initiate in North Dakota and push northeastwards through the Red River Valley. It looks like precipitation will most likely be showers or weak thunderstorms, however the outside chance exists that an isolated severe thunderstorm may be seen. A thunderstorm outlook later will be issued later today covering all of Southern Manitoba.
A few showers will be likely through the overnight hours as the temperature drops to 9°C or so.
Sunday will be the most significant precipitation day with rainfall intensifying through the morning into the afternoon. There’s some uncertainty as to where the western cut-off will be for the rain, but general consensus at this point is that the entirety of the Red River Valley will see rain on Sunday.[2] Total accumulations are hard to nail down at this point, but look to be in the 25–50mm range.
Sunday
10°C / -3°C
Rain
Things take an unwelcome turn on Sunday evening as colder air works its way into Southern Manitoba on the back-side of the system. Rain may become mixed with or switch over to snow as it begins tapering off. No significant snow accumulations are expected. Temperatures will drop off to around –3°C on Sunday night with winds gradually tapering off.
Holiday Monday A Cool Improvement
Looking ahead to the start of next week, it looks like Monday will mark the transition out of this active pattern we’ve been in. Sunny skies and exceptionally cool weather look to be on tap with highs struggling to get to even 10°C[3]. Conditions will improve over the subsequent days with drier weather and temperatures returning to the seasonal mark.
The GDPS is a bit of an outlier, keeping rain wrapped tightly to the surface low pressure system in Minnesota and keeping the bulk of Sunday’s rain southeast of Winnipeg. ↩
