A big change is on the way for Winnipeg and the Red River Valley; after a stretch of hot and humid weather, the jet stream is plunging southwards and will spread significantly cooler conditions across the southern Prairies.
Today’s weather will be dominated by an upper-level low tracking into North Dakota, shunting the jet stream further south and bringing cooler air into the region. Here in Winnipeg, temperatures will climb to around 21°C this afternoon — some 5°C below normal — with northerly winds at around 15-20 km/h. We may see a few showers in the morning, but most of the day should be cloudy with no rain. Skies will clear out late tonight into the early morning hours of Thursday as temperatures dip to a low near 11°C.
This height anomaly map of the upper atmosphere shows how the jet stream will dive southwards, bringing cooler temperatures to southern Manitoba.
Thursday will bring clearing skies as a broad ridge of high pressure builds into the region. Winds will remain light, and with a bit of sunshine highs should be a little higher than Wednesday at around 24°C. There will be a very slight chance of an isolated shower developing along lake-breeze boundaries in the Interlake and drifting south towards Winnipeg in the late-afternoon, but that the chance is low. Skies will be clear Thursday night with a low near 11 or 12°C once again.
Friday will be more of the same; light northwesterly winds under partly cloudy skies with a high near 24°C. Temperatures will dip down to a low near 13°C on Friday night.
Long Range
Saturday will continue the cooler conditions with a high in the low 20’s, but a passing disturbance will bring a slight chance of some scattered showers or thunderstorms. The remainder of the weekend into next week will bring seasonal to slightly below-seasonal temperatures with mixed skies and occasional chances for showers.
Winnipeg’s seasonal daytime high is currently 26°C while the seasonal overnight low is 13°C.
The heat will stick around for just one more day before a cold front ushers in cooler temperatures that will persist through the remainder of the week. That cold front will also bring the threat of severe thunderstorms to the Red River Valley this afternoon as it slides southeastwards through the region.
Today’s weather focus for Winnipeg & the Red River Valley will be the continued heat and humidity in place and the cold front that will be shunting it out today. Temperatures will rise quickly this morning towards a daytime high near 30-31°C. With dew points still in the 18-20°C range, humidex values will climb into the upper 30’s once again. By early afternoon, a cold front will start slumping southwards into the Red River Valley, bringing with it a risk for thunderstorms.
EC³ Day 1 Thunderstorm Outlook for July 31, 2017
As shown in ECCC’s thunderstorm outlook, there is a chance for severe thunderstorms over the Red River Valley and southeastern Manitoba.
Moisture: Surface dew points near 20°C will provide large amounts of energy for thunderstorms to work with.
Instability: The high dew points will combine with moderately steep mid-level lapse rates to produce MLCAPE values near 2500 J/kg.
Shear: Shear is lacking somewhat; 500 mb winds of 30-35 kt layered on top of south to southwesterly surface winds of 10 knots will produce bulk shear values near 25 kt.
Trigger: A cold front slumping southwards through the region.
The high instability coupled with middling shear but sharp trigger will combine to produce the threat of severe thunderstorms that quickly develop into a multicellular line and move to the southeast.
The primary threat with today’s thunderstorm will be large hail. As shown in ECCC’s outlook, hail up to 5 cm diameter — a bit larger than a golf ball — is possible in the worst storms that form today. Heavy rain will be the second threat as it’s quite likely the rainfall coming out of the line of storms is torrential. Whether or not there’s overland flooding will depend on how quickly the line is moving; at this point, it seems like things will be progressive enough that while the rain will be heavy, it won’t reach severe criteria (50 mm in under 1 hour). There may be strong winds in some of the storms, but it won’t be as common as large hail and heavy rain. There is not a significant tornado threat today.
The biggest uncertainty will be when exactly the thunderstorms start. If they form early, around 1PM or so, then they’ll initiate to the northwest of Winnipeg and move through the city early to mid-afternoon. Should the capping inversion hold longer and storms don’t form until 3-4PM, then it will be likely that the cold front has passed through Winnipeg and the storms fire to the south and southeast of the city. The southern Red River Valley and southeastern Manitoba have a high probability of seeing thunderstorms this afternoon.
Behind the cold front, winds shift out of the northwest to around 20 km/h as skies clear. Temperatures will drop to a low near 17°C tonight.
The 3km NAM model shows a line of thunderstorms moving through the Red River Valley late this afternoon.
Tuesday will start off sunny with skies becoming mixed in the afternoon as a weak disturbance moves towards the region. Temperatures will climb to a high near 26°C, but the humidity will be much more comfortable as dew points fall to the 11-13°C range in the continued light northwesterly winds. There may be a slight chance of some isolated showers in the afternoon. Tuesday night will bring some clearing in the evening, but then more organized cloud will begin moving in ahead of a low that will impact the region on Wednesday. Temperatures will drop to around 11°C.
Wednesday will bring cloudy skies and a good chance of showers to Winnipeg and the Red River Valley. It will be a relatively cool day with highs around the 20°C mark and continued light northerly winds. The chance for showers will taper off in the evening with temperatures dropping to a low near 11°C.
Long Range
The remainder of the work week looks quiet with temperatures near-seasonal, if not a bit below. There may be some chances for showers on Friday or Saturday, but it’s still looking a bit unclear at this point.
Winnipeg’s seasonal daytime high is currently 26°C while the seasonal overnight low is 13°C.
The second half of the work week will bring warm weather to Winnipeg with several chances for showers or thunderstorms.
Winnipeg will see a slight chance of a thunderstorm today as a weak disturbance rolls through the region. While this morning will bring some sunshine, conditions will cloud up midday with a chance of showers or thunderstorms throughout the afternoon. It will be relatively mild despite the cloudier afternoon conditions, though, with daytime highs reaching around 25°C. Winds will pick up out of the south this morning to around 30 gusting 50 km/h. Expect skies to clear out this evening as winds taper off and temperatures head to a low near 15°C.
Thursday will bring mainly sunny skies and warm temperatures as daytime highs climb to 29 or 30°C. Winds will be fairly light, making for a wonderful summer day. A disturbance moving through on Thursday evening will spread cloud into southern Manitoba and bring a chance of showers or thunderstorms overnight into early Friday morning. Temperatures will dip to a low near 17°C.
Despite the chances for rain today through Friday afternoon, some models manage to keep it outside Winnipeg.
Friday will be another warm day with highs around 29°C. An incoming low pressure system will begin spreading cloud into the region midday. By late-afternoon, skies should cloud up completely and yet another chance for showers or thunderstorms move into the region for Friday evening and overnight. Temperatures will dip to a low near 18°C.
Despite several chances for rain, overall there are no strong signals that it will affect a widespread area. As we show in the image above, some forecast models produce essentially no rainfall for Winnipeg. The one thing that can be said with some confidence? Areas closer to the international border have a higher chance of seeing something.
Long Range
The weather this weekend will largely be shaped by a low-moving low pressure system that will track across the province from northwest to southeast. Saturday will bring a chance of showers with risk of a thunderstorm to Winnipeg, which will then looks to transition into a chance of showers overnight into Sunday. High temperatures will likely be slightly below normal with highs in the lower 20’s, but overnight lows will be near-seasonal at around 13 or 14°C.
Winnipeg’s seasonal daytime high is currently 26°C while the seasonal overnight low is 13°C.
Conditions are set to gradually settle as the upper low responsible for the stormy weather of late begins working on an exit from Manitoba. There will be a couple more chances for showers, but conditions will begin improving on Canada Day and lead into a stretch of hot and dry weather.
This morning will start with slight chance of a shower or two through Winnipeg and the Red River Valley as a cold front swings across, but then the chance for any rain quickly drops off and then skies will begin to clear out for the afternoon. Winds will be persistent out of the northwest at 20-30 km/h as temperatures climb to a high of just 19°C. Expect a low near 10°C under partly cloudy skies.
Canada Day
Canada Day will start off with cloud cover moving through the region and a chance of showers as the upper low that has been responsible for the showery and stormy weather the past few days finally moves through. Once the low is past, it should be mainly dry, however an isolated afternoon pop-up shower or two will be possible. The cloud cover should clear out towards the evening. Temperatures will continue below seasonal, with highs only around 19 or 20°C.
Canada Day Temperature & Cloud Forecast for Winnipeg, MB
Time
Temperature
Cloud Cover
7:00 AM
14°C
40%
10:00 AM
17°C
80%
1:00 PM
19°C
80%
4:00 PM
19°C
60%
7:00 PM
19°C
40%
10:00 PM
16°C
20%
1:00 AM
13°C
10%
Heading into the evening, temperatures will gradually fall towards the mid-teens for fireworks at 11PM. The clearing skies combined with lowest mosquito counts in 40 years should make for very pleasant viewing conditions! Just remember to bring a sweater! Temperatures will fall to a low near 11°C overnight.
A narrow band of showers is expected to produce 5-15mm of rain across a portion of the Red River Valley on Saturday morning.
Sunday & Beyond
Sunday will be a positively pleasant day compared to the last while. A sunny morning will give way to mixed skies in the afternoon as temperatures climb to a high near 23 or 24°C. No rain! Temperatures will then dip to a low near 14°C under partly cloudy skies.
All indications are that the heat is on next week! Temperatures are set to climb into the upper 20’s by midweek with increasing humidity as well. By the second half of next week, daytime highs near 30°C combined with dew point values near 17°C will make for days that feel like the mid-30’s. It also appears that it will be fairly dry, although Tuesday may bring the potential for some thunderstorm activity.
It’s worth noting that in addition to the warm daytime highs, the higher dew points expected to move into the region will also keep overnight lows mild — likely in the 17-19°C range — so it would be good to ensure that if you have air conditioning that it’s ready for the summer! It looks like the first blast of hot, muggy weather is on the horizon.
NAEFS 8-14 Day Temperature Anomaly Forecast — Valid July 7 – 14, 2017
Heading into the longer-range, ensemble guidance continues to suggest that southern Manitoba will continue to see above-seasonal temperatures. It appears that the cooler temperatures of June will be left in the dust by the first significant stretch of summer warmth.
Winnipeg’s seasonal daytime high is currently 25°C while the seasonal overnight low is 13°C.
