Category: Forecasts

Seasonably Cool Temperatures Ahead, Chance of Rain for Thursday

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In a stark contrast to the past weekend, a ridge of high pressure will keep temperatures seasonably cool much of this week. A passing low pressure system will bring milder temperatures on Wednesday followed by a chance of rain on Thursday.

RDPS 2m Temperature Forecast valid 21Z Tuesday August 27, 2024
Seasonably cool temperatures will sit over southern Manitoba today while warmer weather builds back into the western Prairies.

An Arctic high trundling east across northern Manitoba will keep temperatures cool and the humidity dry today. A disturbance rolling across North Dakota towards Lake of the Woods will bring cloudy skies into the region later this morning. Combined with a light northeast wind, daytime highs will be cool at around 20 °C in the Red River Valley.

Skies will clear this evening as the disturbance heads off into Ontario. The Arctic high will trundle towards James Bay, shifting the light winds in the Red River Valley southerly. Temperatures will dip down to a low near 10 °C.

On Wednesday, the next weather system to impact the region will begin taking shape. A vigorous upper-level disturbance will move from the British Columbia interior into today to southern Alberta by Wednesday. As this tracks east, it will pump much warmer air back into Saskatchewan as a low pressure system develops over the central Prairies. By Wednesday morning, a low will sit over central Saskatchewan with a warm front that drops southeast across southern Manitoba and a cold front southwards towards the Montana/North Dakota border.

This system will bring southerly winds to Winnipeg on Wednesday up to around 30 gusting 50 km/h. Temperatures will be warmer with highs in the mid-20s under mainly sunny skies. In the evening, a low-level jet — a corridor of fast-moving air about 1.5 to 3 km above the ground —will develop with wind speeds around 60 km/h (30–35 knots). These will help develop and sustain a band of showers and thunderstorms through the night that extend from North Dakota northwest to central Saskatchewan. For areas in southern Manitoba, there will be a low risk of a severe thunderstorm on Wednesday night with large hail and wind gusts the main hazards.

24hr. Precipitation Accumulation Forecast valid 00Z Friday August 30, 2024
One model’s forecast for daily rain accumulations on Thursday; while likely too widespread, it shows that showers are possible across much of southern Manitoba on Thursday.

Temperatures will dip to a low in the mid- to upper-teens on Wednesday night with moderate southeast winds continuing.

The band of [thunder]showers will reach Winnipeg either late overnight or early Thursday morning, then sunny breaks will develop after they pass as winds shift westerly. Temperatures will climb back up to the low 20s with mixed skies and a chance of more showers in the afternoon.

Temperatures will head to a low in the mid-teens on Thursday night with partly cloudy skies and west-northwest winds of 20 to 30 km/h.

Long Range Outlook

Settled conditions will redevelop for the end of the week and into the weekend as the mid-week disturbance heads off. A ridge of high pressure will build in from the west and bring settling conditions and sunnier skies.

Daytime highs should sit in the 20 to 25 °C range through the weekend with overnight lows slumping from the mid-teens to around 10 °C.

It’s a pretty pleasant forecast, and will be a nice recovery from the intense heat and humidity the region experienced over the weekend. I hope families with kids can get out there and enjoy the final days of summer before school kicks off again!

Today’s seasonal daytime high in Winnipeg is 24 °C while the seasonal overnight low is 10 °C.

Hot & Humid Conditions Ahead With Severe Thunderstorms Possible Sunday

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An energetic and dynamic weather system lifting through the Prairies will bring hot and humid weather to Winnipeg this weekend. As it passes through on Sunday, severe thunderstorms will be possible across the region.

RDPS 2m Temperature Forecast valid 21Z Saturday August 24, 2024
Hot and humid weather will build into the southeastern Prairies this weekend.

Now that the morning fog and stratus has burnt away, it will get cooking over the Red River Valley. Temperatures will climb close to 30 °C with dew points close to 20 °C making it feel like the upper 30s through the afternoon.

Heading into the night, a low pressure centre will develop over southern Alberta and begin moving northeast. As it forms, it will begin to lift a warm front northwards out of the United States. This will bring partly cloudy conditions to the region overnight with strengthening southerly winds. Winds in Winnipeg will likely reach around 20 km/h by early Saturday morning, then quickly strengthen into the 30 to 40 km/h range as it warms up.

Saturday will bring mixed skies to Winnipeg with a high in the low 30s. Dew point values should sit in the high teens, though an axis of ≥ 20 °C dew points is forecast to lie immediately west of the Red River Valley. This again will result in humidex values in the upper 30s through much of Saturday.

It will be a hot, muggy night on Saturday night with overnight lows dipping only into the low 20s. The breezy southerly winds should continue through the night under partly cloudy skies.

Severe Thunderstorm Threat Develops on Sunday

The system moving through the Prairies, in addition to the heat and humidity here, will bring multiple rounds of potentially severe thunderstorms to the broader region. Severe thunderstorms are possible this afternoon over southwestern Saskatchewan; these storms will blossom into an area of showers and thunderstorms that track northeast across southern Saskatchewan overnight. On Saturday, another round of severe thunderstorms are possible beginning near the Manitoba/Saskatchewan border in the afternoon and spreading northeast across the Interlake through the night. Much of this activity is expected to stay north of the Trans-Canada Highway corridor in the Red River Valley, but isolated thunderstorms look possible in SW Manitoba.

By Sunday, though, it becomes the Red River Valley’s turn for thunderstorm activity. Sunday will likely be the warmest, muggiest day of the three with highs in the low 30s and dew points climbing into the low 20s, making it feel a lot closer to 40. The southerly winds will weaken in the afternoon as a warm-sector trough moves into the region.

For the enthusiasts out there: both the dynamic and thermodynamic setup for Sunday points towards a potent thunderstorm risk. The heat and humidity will drive MLCAPE values to over 2,500 J/kg, while late the day the right entrance to a 50 knot jet streak at H500 slides over the region. Surface winds ahead of the warm-sector trough are solid at 15 knots out of the SSE, but winds become weak and disorganized between the trough and the cold front. Bulk shear values are roughly 30 to 35 knots. MLLCL values are forecast to be moderate, roughly around 3,000 feet. Lastly, PWAT values will climb above 45 mm with Bunker storm motion values around 15 to 20 knots out of southwest.

NAM MLCAPE Forecast valid 21Z Sunday August 25, 2024
An axis of significant amounts of instability, capable of producing dangerous thunderstorms, will develop over the Red River Valley on Sunday.

The result of all that is that there is a potent thunderstorm risk that will develop on Sunday afternoon. Either the warm-sector trough or approaching cold front could be drivers for initiation, and both will be capable of producing dangerous thunderstorms capable of producing all modes of severe weather: very large and damaging hail, wind gusts of 90 to 120 km/h or higher, tornadoes, and torrential downpours capable of localized flash flooding.

All storms will have a roughly equal chance of producing damaging hail or wind gusts. There is a non-zero tornado threat across the region, though it will likely be maximized south of Winnipeg; a weak low centre is forecast to develop over northwestern North Dakota and weaken as it tracks northeast; if it holds together it could result in a stronger, more backed surface flow towards the southwestern Red River Valley that could enhance the tornado risk. Every thunderstorm will produce very heavy rainfall, but relatively high storm motions will likely limit the amount of rain a single storm gives to any one place. Widespread amounts of 20 to 50 mm are possible with the thunderstorm activity. If an area happens to have multiple thunderstorms pass over them, or a storm lingers for a longer period, then accumulations of 50 to 125 mm will be possible.

The thunderstorm activity will track east into the evening, pushed along by an advancing cold front moving through the region. Temperatures will head back down into the upper teens with a moderate northwest wind overnight.

Long Range Outlook

Next week will be an unsettled one for the region with seasonal temperatures. Monday should be pleasant, then cloud and showers will be possible on Tuesday as the region is clipped by a system moving through the Dakotas.

Showers and thunderstorms will again be possible on Wednesday evening through Thursday as another low pushes into the Prairies.

And that’s it for today! Stay safe in the heat, enjoy what you can, and make sure to check on anyone you know who’s more vulnerable (especially on Saturday night).

Be sure to stay tuned for any alerts issued by the MSC in the days to come.

Today’s seasonal daytime high in Winnipeg is 24 °C while the seasonal overnight low is 11 °C.

Summer Warmth Continues With Chance of Mid-Week Showers

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 Beautiful summer weather will continue in Winnipeg, though a disturbance passing mid-week could bring showers to the region.

RDPS 2m Temperature Forecast valid 21Z Tuesday August 20, 2024
It will be a hot day in the Red River Valley on Tuesday with highs near 30 °C.

Warm and sunny weather will continue in Winnipeg thanks to an upper ridge that remains in place over the region. This will leave Winnipeg today in a southerly flow between an area of high pressure over NW Ontario and a developing area of low pressure in southern Alberta.

As a result, it will be another hot day in Winnipeg as temperatures climb to the 30 °C mark with southerlies up to around 20 km/h. Skies will become mixed today as cloud cover left over from a disturbance in Saskatchewan drifts through the region. Temperatures will dip into the mid-teens tonight with light winds and a few clouds.

Wednesday will be another pleasant day with temperatures climbing up into the upper 20s and southerlies up into the 20–30 km/h range. A mainly sunny start to the day will give way to a few clouds in the afternoon. All in all, a beautiful day.

Wednesday night will bring a change in the weather as a low pressure system begins to track east across the Prairies. It will spread cloud into Winnipeg on Wednesday night with lows down to around 20 °C.

Thunderstorms will likely develop along this system’s warm-sector trough on Wednesday night, beginning over Montana and southern Saskatchewan and pushing into Manitoba in the early morning hours.

This will bring a chance of showers or thunderstorms to the Winnipeg area on Thursday morning. The chance will steadily s drop from mid-day onwards with sunny breaks developing in the afternoon. Southerly winds up to around 20 km/h will shift southwesterly by the end of the day. The cloud cover will keep temperatures cooler with a high in the mid-20s.

Long Range Outlook

Summer heat will return to end the week with daytime highs near 30 °C on Friday through Sunday. Dew point values will persist in the upper teens, making for slightly muggy conditions that feel closer to the mid-30s. And to top it off, Winnipeg should see plenty of sunshine throughout the weekend!

Enjoy that summer warmth while it’s here!

Today’s seasonal daytime high in Winnipeg is 24 °C while the seasonal overnight low is 11 °C.

#awm_rain #awm_thunderstorms #mbstorm #Winnipeg

Settled but Smokey Weather Ahead

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A broad area of high pressure moving through the northern Prairies will bring seasonal conditions to the Winnipeg area this weekend. Unfortunately, northerly winds will also bring several plumes of wildfire smoke through the region over the coming days.

RDPS 2m Temperature Forecast valid 21Z Saturday August 17, 2024
This weekend will bring light winds and seasonal temperatures to much of the southern Prairies.

The Winnipeg area will get a chance to dry out after yesterday’s soaking as the slow-moving system responsible for it trundles towards the Great Lakes. Behind it, a ridge of high pressure will build in from the north as an area of high pressure moves into northern Manitoba this weekend.

This pattern change will bring partly cloudy to mixed skies to the area over the next few days with daytime highs in the mid-20s and overnight lows in the mid- to upper-teens. Winds will stay northerly over the next few days, up to around 30 km/h today then easing to 20 km/h or less for the weekend.

There is a low chance of a brief rain shower this afternoon due to lingering instability, then it will stay dry through the weekend.

The bigger issue in the days ahead will be plumes of wildfire smoke that descend through the region in the northerly winds.

CAMS PM2.5 forecast valid 17Z Friday August 16, 2024
The CAMS air quality model shows a broad plume of elevated PM2.5 values from wildfire smoke through much of Saskatchewan and western Manitoba today.

Today, dense plumes of smoke will move through portions of western Manitoba and Saskatchewan, sourced from wildfires over west-central Manitoba and northern Saskatchewan. Additionally, a secondary plume from wildfires in the Island Lake region in northeast Manitoba will drift southwest across the southern Interlake into the southwest corner of the province.

For Winnipeg, smoke models are trending towards keeping the smoke west and north of the city, but there is a chance that the city is caught by the edge of the plume this afternoon. If that happens, AQHI values will likely climb into the 6 to 8 range for the afternoon with improvement on Friday evening across the Red River Valley and western Manitoba.

CAMS PM2.5 forecast valid 23Z Saturday August 17, 2024
On Saturday, a potentially dense plume of wildfire smoke will drift towards the Red River Valley from the fires near Island Lake in NE Manitoba.

Heading into Saturday, a dense plume of smoke is forecast to drift from the Island Lake fires southwest into the Red River Valley. Unfortunately, if this happens the plume will end up stalling out under the ridge of high pressure over the Red River. This plume is forecast to arrive by Saturday afternoon and persist through midday Sunday before clearing. AQHI values with this plume could be as high as 10+.

AQHI values of 4 to 7 suggest that people with sensitivities to air quality should consider reducing their exposure. When values reach 7 to 10, all should consider reducing their exposure. AQHI values of 10 or higher are unhealthy and everybody should minimize their exposure.

Long Range Outlook

The ridge of high pressure will shift to the east on Monday, bringing southerly winds back to the region. Temperatures will climb back into the upper-20s with mainly sunny skies. The southerly winds will push wildfire smoke back northwards, bringing cleaner air to the southern Prairies and worse air quality to the northern Prairies.

Today’s seasonal daytime high in Winnipeg is 25 °C while the seasonal overnight low is 12 °C.