The beautiful summer weather will stick around for one more day before a large upper trough pushing across the Prairies spreads showers and generally unsettled weather into Southern Manitoba.
Forecast precipitation for Wednesday night from the RDPS.
Today will be an almost ideal summer day across much of the Red River Valley. Sunny skies will gradually see increasing cloudiness through the afternoon hours, however before things cloud up temperatures will climb all the way up to around 27 or 28°C while light winds begin picking up in the afternoon to 20-30km/h.
Wednesday
27°C / 14°C
Increasing cloudiness in the afternoon.
The story will be a little different over southwest Manitoba today, where an incoming surface trough will combine with warm weather and moderate instability to produce mid-to-late afternoon thunderstorms. Around 1250J/kg of CAPE will combine with 25kt of bulk shear and a 25-30kt LLJ to support upscale growth from a few isolated thunderstorms to an eastward moving line by the evening. This line will weaken fairly quickly as it moves into the Red River Valley thanks to the loss of daytime heating and the storms moving away from their main support.
The overall threat of severe weather in southwest Manitoba is marginal. The main risks will be large hail, but that seems like a fairly off chance at best. A rogue wind gust can’t be ruled out either, but again, I don’t have particularly high expectations for severe weather. Were I the SPC, it would be a “See Text” sort of day.
This line will bring a chance of showers or thunderstorms to Winnipeg and the Red River Vally through the overnight hours. No severe weather is expected. Temperatures will drop down to around 15°C or so.
Thursday & Friday
Thursday
25°C / 10°C
Cloudy periods; slight chance of showers.
Friday
21°C / 8°C
A mix of sun and cloud.
Tomorrow will bring cloudy periods with a slight chance of showers through the day. The precipitation risk will increase towards evening as a second impulse digs the upper trough into Manitoba, leaving us with a chance of showers on Thursday night.
Cooler air will also start filtering in. Thursday’s high of 25°C will be replaced by cooler weather for the remainder of the week and weekend. The temperature will drop to around 10°C on Thursday night.
Things should push off to the east on Friday morning leaving behind some sunny skies, but skies look to become mixed midday. There may be a chance of seeing some rain on Friday afternoon, but guidance is very mixed right now as to whether or not a band of rain will push northeastwards out of North Dakota. At this point it seems more likely that things will stay dry than not. We’ll see highs across the Red River Valley top out around the 21°C mark. The overnight low on Friday night will drop into the high single digits.
The Weekend
The weekend across the Red River Valley is looking fairly nice, albeit a little cool. Saturday will see afternoon cloudiness bring a slight chance of late-day showers. Sunday looks fairly sunny, although cloud will likely increase in the evening ahead of another system forecast to push through the region on Monday. Highs will sit near the 20°C mark with overnight lows in the mid-to-high single digits.
The first part of this week will feature fairly typical early-June conditions, with temperatures in the low twenties and a chance of rain.
Areas along the International Border may see some rain on Monday
Monday
Monday
18°C / 9°C
Chance of Showers
Today will see a chance of showers over all of southern Manitoba. In areas near the International border, there may be more than showers, with periods of rain and perhaps even some embedded thunderstorms. Accumulations along the border should generally not exceed 15mm, but there could be locally higher amounts if any thunderstorms develop. In areas further north, such as Winnipeg, it should be a fairly uneventful day overall, with temperatures in the upper teens and a breezy north wind.
Tuesday and Wednesday
Tuesday
23°C / 10°C
Mainly Sunny
Wednesday
25°C / 13°C
Mainly Sunny
Tuesday and Wednesday look like uneventful days in southern Manitoba. Temperatures will be in the low to mid twenties with light winds and mainly sunny skies. There’s certainly nothing wrong with that!
Long Range
The long range forecast suggests we may see a risk of thunderstorms on Thursday, followed by cooler weather for late week into the weekend. We’ll likely rebound to seasonal or above-seasonal values at some point next week.
Saskatchewan/Manitoba Border Chase – May 29th, 2014
Three quarters of the A Weather Moment team (plus a U of Manitoba student) went storm chasing on Thursday. This is a summary of what happened, written by Scott.
We left Winnipeg around 11am and drove straight to Brandon, arriving by 1:30pm. Once in Brandon we made our obligatory stop at Subway and reassessed the situation. We figured from Brandon we’d have to go west for sure, but the question was whether to go straight west, north-west, or south-west. We opted to not commit, and just drive another 45min west to Virden to reassess there again.
While in Virden we noticed a decent looking cell coming out of Saskatchewan, but it was expected to move well north into the Riding Mountains. We drove toward it a bit in case it decided to right move, but of course it did not (it was heading into the forest), so we then backtracked to Virden. On our way back we saw some good activity developing near Melita, so we went to investigate that. Upon arrival in Pipestone (just north of Melita), we got a clear view of that Melita storm, but it was featureless and high based…yuck. It then appeared that there were some supercellish structures coming out of Saskatchewan, so we figured we’d check them out. The surface winds in their vicinity had already switched to westerly, but we figured if they moved into Manitoba quickly enough they might have a chance. However, we quickly found out they were already too far behind the front for that to happen. So that was that, no supercells for us! We then turned around and started heading for home.
High based storm near Pipestone; featureless with a rain/hail shaft. (Taken by Matt)
As we drove back, a couple of core punches were performed around Brandon to get through a line of storms. Upon reaching the other side of the line near Carberry it was getting dark, so we decided to stop for lightning pictures – good idea. The lightning was beginning to pick up and some CG strikes were noted. It then began to rain and we moved east again to Portage and stopped for more pictures – very good idea! In Portage there were powerful CG strikes every 5-20 seconds (roughly), which made for many really great pictures. We took pictures there for a while, but then it started to rain again, so we moved east again, this time to Oakville.
Fork lightning south of Portage. (Taken by Matt)Overall, it was a disappointing day for daytime storms, but the nighttime lightning made up for a lot of that. Even though the storms weren’t that great, it was still a fun day just chatting and joking about our misfortune. It’s only May after all, so we’re still in a bonus month for storms as far as I’m concerned.
Southwestern Manitoba will be under the gun again for the potential of strong to severe thunderstorms.
In what has suddenly become a somewhat busy start to the season, more thunderstorms are expected through the remainder of the week, with a threat for severe thunderstorms tomorrow in the southwest corner of the province.
Today & Tomorrow
Wednesday
25°C / 13°C
Cloudy periods
Thursday
28°C
Chance of morning showers or thundershowers. Risk of a thunderstorm late in the day.
Thursday Night
15°C
Showers or thunderstorms likely.
In Winnipeg today we’ll see some cloudy periods but overall a very nice day with light winds and a high near 25°C. The main focus for weather will begin in Southern Saskatchewan where conditions are very favourable for severe thunderstorms. Storms will likely initiate mid-afternoon in south-central Saskatchewan and begin tracking eastwards.
The storms will quickly grow into supercells thanks to ample available energy and strong veering wind profiles. The storms across Southern Saskatchewan will carry with them the risk of all severe modes of weather: damaging winds, flash flooding due to torrential downpours, large hail and tornadoes. It will be a potentially dangerous afternoon in south-central Saskatchewan.
The RDPS 3hr. precipitation panel depicts the strong thunderstorms in south-central Saskatchewan this afternoon.
The storms will continue northeastwards through the overnight period, sustained by a strong low-level jet. The storms will enter Manitoba later in the overnight period, with the main focus through the Parkland region, but with the potential for storms extending southwards into SW Manitoba to the US border. At this point, it doesn’t appear that the storms would carry a significant severe threat, but there does seem to be a slight chance that they would be able to produce marginally severe hail if they do develop.
We’ll see the remainders of that convection move through the Red River Valley Thursday morning. It may still be thunderstorms at that time, it may just be some scattered showers and cloud; it will depend highly on exactly what develops in the overnight period.
Moving into Thursday afternoon, the thunderstorm risk returns to Southern Manitoba with a slight risk of severe thunderstorms in southwest Manitoba and possibly creeping into the southwestern Red River Valley. A low pressure system lifting northeastwards through the province will drag a cold front slowly eastwards through the afternoon. While a few unknowns still hinder the forecast – primarily what effect morning convection may have on the environment and how much cloud will linger, preventing things from warming up too much – the setup looks favourable for the development of strong to severe thunderstorms.
Updated issue of our thunderstorm outlook for Thursday afternoon through to Friday morning. View initial outlook.
A favourable storm environment will be in place by the afternoon hours in southwest Manitoba, with CAPE values exceeding 1500J/kg, decent convergence along the cold front, very unstable mid-levels and a fairly favourable vertical wind profile. It seems quite plausible that supercell thunderstorms could develop along the cold front in the mid-to-late afternoon and then slowly track eastwards. Should severe storms develop, all modes of severe weather would be possible, including localized flash flooding, large hail, and strong winds. Tornadoes cannot be ruled out, however the low-level wind structure may not be quite conducive enough to generate the required environment.
The forecast sounding from Brandon clearly depicts the capping inversion in place on Thursday afternoon.
Some uncertainty plagues the forecast, however, and it’s mainly focused on the “cap” in place. A “cap”, or capping inversion, is a layer of warm air usually somewhere in the first 2-5km of the atmosphere that inhibits air being lifted from the surface from continuing to higher altitudes. This feature can be overcome with enough forcing, which then allows the air parcel to rise since it’s warmer than the air around it – depicted with red shading in the image.
If the cap stays strong, there will be little hope for storms until late evening into the overnight period, and those storms would only be marginally severe.
It seems likely, though, that the cold front will erode the cap and provide enough forcing to generate thunderstorms, so our current outlook calls for a slight risk of severe thunderstorms over southwestern Manitoba into the Red River Valley. There is a chance that we may push the slight risk area further north and northwest, including more regions along the Trans-Canada Highway as well as some areas in Parkland Manitoba, but we’ll wait for further evidence that supports that move before we jump on that.
The storms will slowly track eastwards and showers and thunderstorms are likely over much of the Red River Valley overnight Thursday into Friday morning.
Friday & Beyond
23°C / 15°C
Showers likely, then clearing in the afternoon.
Friday will bring the remnants of any precipitation along the cold front through the Red River Valley in the first half of the day, then we’ll see clearing skies as this system pushes off to the east. The high will be near 23°C and the temperature dip into the mid-teens on Friday night.
The weekend is looking drier for the most part. A system tracking through North Dakota may spread some rain into the southern Red River Valley, but at this point its looking like things should remain south of the border. Sunday looks like quite a pleasant day with sunny skies and temperatures in the mid-20’s.
AWM Chase Day
Much of the AWM team will be out chasing storms in SW Manitoba today. You can follow along with them through their tweets here:
Tweets from https://twitter.com/aweathermoment/lists/the-awm-team
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