Labour Day Brings Windy, Cool Conditions and Chance of Showers

The passage of a cold front this morning will usher in strong northerly winds and bring scattered showers to the Red River Valley as a blast of Arctic-sourced air spills southwards into the region. The cool conditions will stick around for the first half the week, but temperatures are set to soar again heading into the weekend!

There’s no getting around it: today is going to feel positively fall-like as a cold front moves through this morning and blasts Winnipeg and the Red River Valley with winds of 40-50 km/h and gusts up to 70 km/h as a surge of Arctic air spreads southwards in its wake. Temperatures will reach a high of just 19°C today under mixed skies with widespread showers as an upper-level trough swings through behind the front.

With such strong winds in the region, if any thunderstorms manage to develop, they will have the potential to produce severe wind gusts in excess of 90 km/h. Additionally, marginally severe hail1 is possible due to very low freezing levels, but larger quantities of small hail would be more likely from any thunderstorms that could manage to develop today.

RPDS 10m Wind Speed Forecast valid 21Z Monday September 4, 2017
Strong winds (pink) will be in place over the Red River Valley Monday afternoon.

Winds will ease tonight as temperatures head to a low around 9°C under partly cloudy skies. Tuesday will continue to be windy out of the north to northwest at 30-40 km/h with gusts up to around the 50 km/h range, but skies will be sunnier and no rain is expected. Temperatures will be similar to Monday with highs around 19°C. Tuesday night will be quite chilly as temperatures dip to a low near 5°C or so as a large ridge of high pressure moves into the region.

Wednesday will mark the start of a turnaround back towards positively summer-like heat. Winds will be light out of the west under mainly sunny skies as temperatures climb to a high of 21°C. While it’s not a huge improvement from Tuesday’s temperatures, it marks the departure of the large ridge of high pressure bringing the cool temperatures as it slumps off to the south. In its absence, the upper-level ridge that is bringing very warm temperatures to western Canada will begin to work its way across the Prairies.

Long Range

NAEFS 8-14 Day Temperature Anomaly Forecast — Valid September 11-18, 2107
NAEFS 8-14 Day Temperature Anomaly Forecast — Valid September 11-18, 2107

Temperatures are set to soar through the latter half of the week with highs in the upper 20’s on Thursday and Friday, then potentially reaching the 30°C mark on the weekend. Temperatures are then expected to remain above-normal through the remainder of next week. Additionally, there’s essentially no chance for rain from Thursday onwards through next week in current forecasts as persistent upper-level ridging shifts the storm track well to our north.

Winnipeg’s seasonal daytime high is currently 21°C while the seasonal overnight low is 9C.

  1. EC³ condensers severe hail to be the size of a nickel (21mm) in diameter or larger.

Showers on Friday, Long Range Shifts To A Nicer Outlook

A low pressure system and cold front moving through Manitoba today will bring morning showers or thunderstorms to the Red River Valley and a follow-up chance for rain this afternoon. Once this system clears out, there’s good news ahead as the long-range forecast has shifted to a more optimistic outlook!

To start Friday off Winnipeg & the Red River Valley will see cloudy skies with a good chance of showers as a line of precipitation moves into the region from the west. That line should be through by 8 or 9AM, and then Winnipeg will be left with cloudy skies and a breezy southerly wind near 30 gusting to 50 km/h as temperatures climb towards a high near 24°C. Then, around 2-3 PM, the threat for thunderstorms will redevelop — primarily for Winnipeg south to the US border and areas east — as a cold front moves across the region. Strong thunderstorms are likely with this front with the potential for isolated to scattered severe storms. The main threat with this afternoon’s thunderstorms will be large hail between the size of nickels and loonies alongside gusty winds. Things will calm down this evening as the wind swings around to the northwest and temperatures head to a low near 13°C.

PASPC Day 1 Thunderstorm Outlook valid September 1, 2017
The PASPC Thunderstorm Outlook highlights well where severe thunderstorms are possible today.

Late Saturday night into early Sunday morning, it appears a weak disturbance will roll through the region. It will mainly bring a bit of cloud to the region but there will be a small chance of some early morning showers on Saturday. Once it moves out, though, Winnipeg will be set for a beautiful day as weak ridging moves into the area, bringing mainly sunny skies, light winds, and temperatures in the mid-20’s.

GDPS Surface Temperature Forecast valid 21Z Sunday September 3, 2017 with annotations
A low pressure system passing through Manitoba on Sunday will bring warm temperatures to the Red River Valley

Another low pressure system is then forecast to move across the Interlake on Sunday, drawing very warm air eastwards and pushing daytime highs up in into the low 30’s. Winds will be breezy out of the south at 30-40 km/h, and Winnipeg can expect partly cloudy skies. Temperatures will then dip back to around 13°C again on Sunday night with a breezy northwesterly wind.

Long Range

The long-range forecast is looking much better than it appeared it would be earlier this week! While a potent shot of cold air is expected to slide southwards behind Sunday’s system, dropping high temperatures on Monday and Tuesday into the upper teens, the cool weather is now expected to be short-lived. Instead of being stuck on the edge of a large upper-level trough as an upper-level ridge sits over BC, models have moved towards a more progressive pattern, allowing the ridge to push eastwards relatively quickly. This means a return to seasonal temperatures by mid-week instead of week’s end.

Otherwise, fairly quiet weather on tap for next week.

Winnipeg’s seasonal daytime high is currently 21°C while the seasonal overnight low is 9C.

Unsettled Friday Ushers In Transition To Cooler Conditions

Temperatures will hover at seasonal to slightly above-seasonal values until a low pressure system moves through on Friday and kicks off a major pattern change that will bring significantly cooler weather to the region.

Winnipeg has a couple nice days ahead as a ridge of high pressure keeps skies fairly clear and temperatures continue slightly above normal with highs in the mid-to-upper 20’s. Winds will be light today, but pick up out of the south on Thursday to around 30-40 km/h as a trough of low pressure moves into Saskatchewan. Tonight will see a low near 12°C, but on Thursday night a combination of cloud cover moving in, continuing windy conditions, and increasing dew points will keep lows much higher at around 17°C.

RDPS 24hr. QPF valid 00Z Saturday September 2, 2017
Models indicate that much of Manitoba will see some form of rain on Friday…except for Winnipeg?

Friday’s main focus will be a low pressure system tracking eastwards through the province. At this point, it appears that it will likely develop an area of thunderstorms over Saskatchewan on Thursday afternoon, then track into Manitoba overnight. The exact placement and timing of the system has a lot of uncertainty at the moment simply due to the unpredictable nature of convection in the long-range, but in general it appears that Winnipeg will see a chance of showers or thunderstorms from fairly early in the morning until mid-afternoon or so, followed by winds shifting out of the northwest and clearing skies. It will also be a bit of a muggy day with dew points climbing into the upper teens. We’ll be able to paint a much clearer picture of this system in our next forecast post.

Long Range

The biggest weather story for the region will be the transition that takes place behind Friday’s system. Once it moves through, the upper-level ridge over western Canada is expected to amplify quite significantly, bringing another heat wave to B.C. and portions of Alberta. The flip-side to that will be the digging of a long-wave trough over central Canada, which will bring a northwesterly flow to our region and allow much cooler air to spill southwards out of the Arctic.

GDPS Forecast 500mb Height Anomaly valid 18Z Wednesday September 6, 2017
By the middle of next week, a deep upper-level trough is expected to be in place over eastern Canada, bringing cooler conditions to Manitoba.

This could bring daytime highs as cool as 15-16°C by early next week, around 5°C below normal. This pattern would also likely bring partly cloudy to mixed skies and occasional chances for showers. It appears conditions will begin returning towards normal late next week and through the weekend.

Winnipeg’s seasonal daytime high is currently 22°C while the seasonal overnight low is 9C.

Conditions Improve Through The Weekend

A return to summer conditions is on tap for Winnipeg as an upper-level ridge builds in behind a low pressure system that will move through on Saturday.

After a distinctly fall-like morning on Thursday where temperatures dipped as low as 3.1°C at the Winnipeg Airport, many will be relieved to hear that summer is on the way back to the region as the ridge of high pressure that brought the cold weather pushes off to the east and warmer conditions being working in from the west.

The first push of warmer weather will begin working into the region today as a slow-moving trough moves eastwards across Saskatchewan. Skies will remain fairly sunny today, but winds will pick up out of the southeast to around 30 km/h as the temperature climbs to a high near 26°C. Clouds will begin working into the region on Friday evening as the winds ease and temperatures drop towards a low near 15°C.

Temperatures will climb to slightly above-seasonal values across Southern Manitoba today.

Saturday will bring mainly cloudy conditions to Winnipeg as the broad trough of low pressure moves through the region. At the moment it looks unlikely that Winnipeg will see much in the way of precipitation, but if there is going to be any rain it would likely be in the afternoon or evening as the trough line swings through. The odds seem low, though, as the main areas of support for rain will pass by to the north and south, leaving Winnipeg & the Red River Valley in a bit of a gap. The cloudy skies will keep temperatures slightly cooler than Friday with highs near 23°C. Skies will clear out on Saturday night with temperatures dipping to a low near 14°C.

Winnipeg may dodge all of the rain moving through the region on Saturday as one feature passes to the south and another to the north.

Summer weather returns to Winnipeg for Sunday! There may be some low cloud or fog early in the morning, but that should burn off fairly quickly leaving the region with mainly sunny skies. Temperatures will be warm with highs reaching around the 28°C mark in the Red River Valley. Expect a low near 15°C on Sunday night.

Long Range

Next week will start off quite warm with highs in the upper 20’s and then trend towards more seasonal temperatures midweek. Things look to turn slightly more unsettled near the end of the week with rain and thunderstorms possible.

Winnipeg’s seasonal daytime high is currently 23°C while the seasonal overnight low is 10°C.