Cooler Weather Settles In

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Just like that, fall weather has arrived in the Red River Valley with temperatures over 10 °C cooler than seen on the weekend.

RDPS 2m Temperature Forecast valid 12Z Friday October 4, 2024
The first freeze of the season could arrive by Friday morning.

Today marks the start of fall weather in southern Manitoba, courtesy a much cooler air mass brought in by yesterday’s cold front and very gusty winds. This change reflects a major shift in the large-scale weather pattern; the upper ridge over the Prairies has collapsed, and a quasi-stationary upper low is becoming established over the western coast of Hudson Bay. This change will result in a more west to northwest flow aloft over Manitoba, ushering in seasonal conditions for this time of year.

The result will be a week filled with daytime highs in the mid-teens and overnight lows dropping into the 0 to 5 °C range with a risk that we may see the first frosts of the season.

For a bit more detail, today will bring cloudier conditions with lighter winds than yesterday. A high pressure system passing to the south will spread southwest winds of 20 to 30 km/h into the region as temperatures climb into the mid-teens. A weak disturbance slumping southeastwards across the Prairies will keep conditions cloudy tonight; this will ensure that the overnight low stays mild (for this week) at around 10 °C.

Another cold front will sweep through on Wednesday, bringing gusty northwesterlies and cooler temperatures back to the region. With the cooler temperatures moving in and the prolonged northwesterly flow, some lake-effect showers may develop. Winds will likely keep these north of Winnipeg, but worth noting the possibility for areas in the northern Red River Valley.

A ridge of high pressure will push into the province behind the front, bringing clearing skies and sending overnight lows to near-freezing for the rest of the work week. A widespread freeze could be possible over southern Manitoba overnight Thursday into Friday morning.

Long Range Outlook

A moderating trend will develop over the weekend across southern Manitoba with daytime highs heading back towards the upper teens. Overnight lows will also follow the warming trend, likely heading back into the 5–10 °C range through the weekend.

The region will see variable cloudiness, but little to no precipitation is expected.

Today’s seasonal daytime high in Winnipeg is 15 °C while the seasonal overnight low is +3 °C.

Warm Early Fall Weather Continues Through the Weekend

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Warm and sunny weather will remain in place across southern Manitoba this weekend.

RDPS 2m Temperature Forecast valid 21Z Sunday September 29, 2024
A low pressure system moving into Saskatchewan will bring very warm weather to southern Manitoba on Sunday.

A southwesterly flow aloft will sit over the southern Prairies this weekend and continue to push warm air into the region. With the storm track shunted northwards of the region, Winnipeg and area will see sunny skies that last right through the weekend.

Daytime highs will climb from the low 20s today into the mid- to upper-20s this weekend. Overnight lows will hover around 10 °C tonight and tomorrow, but a push of warmer air on Sunday night will keep lows warmer in the mid-teens.

Winds today will be light, eventually picking up out of the south into the 15 to 25 km/h range this afternoon. A weak high pressure system moving through on Saturday will bring light northerly winds to the region. On Sunday, the wind will pick up quite a bit with the push of warmer air moving into the region. Southerly winds will strengthen as high as 50 gusting 70 km/h midday and persist through much of the night before beginning to ease.

All in all, aside from the winds on Sunday, it looks like it’s going to be a beautiful few days ahead.

Long Range Outlook

A low pressure system will cross the province on Monday, bringing a significant pattern change to southern Manitoba. This system will bring showers to the region as a cold front sweeps across the province. In its wake, cooler weather will slump southwards out of the Arctic. This will result in breezy northwest winds, daytime highs slumping into the 10 to 15 °C range, and the chance of some lake-effect showers through the first half of the week.

While there may be a couple blips of warmer weather later in the week, it looks like this marks a shift back towards near-seasonal temperatures for the region for a while.

Today’s seasonal daytime high in Winnipeg is 15 °C while the seasonal overnight low is 4 °C.

Warmer Weather Returns to Southern Manitoba

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An upper ridge building into the Prairies will send high temperatures back into the mid-20s across southern Manitoba.

RDPS 2m Temperature Forecast valid 21Z Thursday September 26, 2024
An upper ridge will bring warm weather back to southern Manitoba this week.

The main weather-maker through the rest of the week will be an upper high that will move from the Pacific coast east towards the American Plains. It will build a strong upper ridge into the Prairies and push temperatures well above seasonal norms.

For Winnipeg, this trend will start with clearing skies today as temperatures climb to a high in the low 20s. For Wednesday and Thursday, sunny skies will blanket the region with highs climbing into the mid-20s. The winds will only be notable on Thursday where they will pick up out of the south into the 20 to 30 km/h range.

Overnight lows will range from the low to mid-teens over the next few days.

Long Range Outlook

The upper ridge will linger over Manitoba as it begins to break down near week’s end. This will mean mainly sunny conditions should continue into the weekend with daytime highs in the low to mid-20s.

Today’s seasonal daytime high in Winnipeg is 16 °C while the seasonal overnight low is 4 °C.

Warm Late-Summer Weather Continues

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A persistent southerly flow over southern Manitoba will keep the seasonably warm and humid conditions in place for a for a few more days.

RDPS 2m Temperature Forecast valid 21Z Wednesday September 18, 2024
A stalled low over eastern Montana will continue to pump warmer air northwards into southern Manitoba this week.

A quick note to start: the lack of forecasts last week was due to the fact that I’m dealing with a long-lasting bout of COVID–19 that’s sidelined me for a while now. I’m on a [gradual] up and up now, with symptoms finally receding after testing positive on rapid tests for a whopping 11 days in a row. Not a fun time, looking forward to getting back at life.

Daytime highs in the mid-20s will continue into mid-week for the Winnipeg area as a persistent low pressure complex to the west supports a southerly flow across the region. Daytime highs for Tuesday and Wednesday will likely sit around 25 °C; it could be a touch cooler if a bit of a stronger cold pool is left behind from overnight convection, or a tad warmer if we clear out early and a stronger southerly flow can develop earlier in the day.

The humidity will also be notable for mid-September, with dew point values in the mid- to upper-teens, potentially reaching around 20 °C on Wednesday. This is more humid that the region often sees at this time of year, but the lower daytime highs in the 20s should keep the worst of the heat effects at bay. In the sun, the heat and humidity could combine to feel like it’s in the low 30s rather than mid-20s.

RDPS 2m Dew Point Temperature Forecast valid 21Z Wednesday September 18, 2024
In addition to the seasonably mild temperatures, it will continue to be humid across southern Manitoba.

Overnight lows both tonight and tomorrow night will sit in the mid-teens.

Weather-wise, today should bring clearing skies as the disturbance that brought rain and thunderstorms to the region yesterday pushes off to the east. A few clouds will begin to build back in tonight, leading to mixed skies on Wednesday as a cold front approaches the region from the west.

A few showers are possible on Wednesday; it looks like they should be weak, though the slow-moving nature of the cold front and broad forcing could result in a narrow band of slow-moving showers that could produce some locally higher amounts in the 15 to 25 mm range. I’m doubtful Wednesday will be a “wet” day, more likely a cloudier one with the chance of passing showers.

The cloudiness and chance of showers will continue into Wednesday night.

Unsettled End to the Work Week

The low that’s been sitting to the west all week will finally get moving on Thursday, moving into southwest Manitoba on Thursday and sliding into northern Manitoba on Friday.

This will bring a notable change in the weather to southern Manitoba. To start, both Thursday and Friday could bring wet conditions to the Red River Valley. On Thursday, showers and thunderstorms will begin possible through much of south-central and southeast Manitoba as the forcing along the cold front picks up with the advance of the low. This activity will likely continue into the night as it pushes northeast.

Winds will finally shift on Thursday from the persistent southerly at 20 to 30 gusting 50 km/h seen much of this week to westerly winds of 15 to 30 km/h.

On Friday, showers in the instability on the back-side of this system may clip through southern Manitoba as cooler air moves into the region. Daytime highs will cool into the low 20s by the end of the work week.

Long Range Outlook

Heading into the weekend, more settled conditions will develop over the region as near-seasonal temperatures return. Winnipeg will see partly cloudy conditions over the weekend with daytime highs in the upper teens and overnight lows near the 10 °C mark.

This trend looks to continue into the start of next week.

Today’s seasonal daytime high in Winnipeg is 18 °C while the seasonal overnight low is 6 °C.