Author: Brad

Brad lives in Winnipeg with his wife and two children and is the founder of A Weather Moment. He has loved weather from a very young age and has followed that passion through his life so far. He received a B.Sc. in Earth Sciences with Specialization in Atmospheric Sciences and is currently employed in the field of meteorology. You can find the author as WeatherInThePeg on Mastodon.

Fall Starts By Putting Summer to Shame

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The first week of fall[1] will start off with weather that will seemingly put this summer to shame. Very warm weather is on the way with potentially record-breaking highs across Southern Manitoba on Thursday!

Wednesday
25°C / 14°C
Cloudy; clearing for a sunny afternoon

Thursday
31°C / 16°C
Mainly sunny; increasing humidity

Friday
30°C / 16°C
Mainly sunny & hot

A prominent upper-level ridge in place over the Prairies has pushed the polar jet stream far northwards and allowed warm air to spread into the Southern Prairies from the United States. As a result, significantly warmer than normal temperatures will continue through the remainder of the week in Winnipeg.

Today will start off fairly cloudy thanks to some stratus cloud that spread northwards ahead of a dissipating trough of low pressure. The cloud should clear out for the afternoon and we’ll see temperatures climb to around 24 or 25°C. The temperature will dip to around 14°C tonight under mainly clear skies.

Thursday and Friday will both bring highs just at or over the 30°C mark under mainly sunny skies. South to southeasterly winds will begin tapping into some moisture from the Central Plains of the US and we’ll see the humidity gradually rise for the latter half of the week. Dewpoint values will climb into the mid-to-upper teens, which when combined with highs near 30°C, it will feel more like the mid-to-upper 30’s. The overnight lows both nights will be in the mid-teens.

Record-Breaking Potential

We have a slight chance of breaking daily record high temperatures on both Thursday and Friday. For Thursday, September 25th the daily record high temperature is 31.1°C set in 1950. For Friday, September 26th the daily record high temperature is 31.7°C set in 1957. Both days will see temperatures climbing to or just above the 30°C mark, and if maximum heating is realized, we may get the bump we need to break one of these records!

Date High Temperature (2014) Record High
September 25 27.7°C 31.1°C (1950)
September 26 30°C (Forecast) 31.7°C (1952)

Cooler Weekend

The weekend is looking great, despite a cool-down that’s in store. Daytime highs will dip around 5°C or so for the weekend with both days seeing highs in the mid–20’s. Fortunately this still puts us around 8°C above normal for the time of year, so there will be little to complain about. We’ll likely see a bit more cloud that we do through the second half of the week, but all in all it will be a gorgeous weekend!

  1. …sort of. Meteorological fall started at the beginning of September, but fall as most people consider it began on September 22nd after the autumnal equinox.  ↩

Above-Normal Weather! Yes!

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Above-normal weather is in store for us this week, it’s about time!

Warm weather is in store this week
Warm weather is in store this week

Monday

Monday
24°C / 11°C
Mainly sunny

Today will be one of the warmest days we’ve seen in some time, with temperatures climbing into the low to mid twenties. Skies will be mainly sunny and winds will be breezy and from the south-west. It will be a very pleasant fall day, perfect for catching up on those outdoor chores that you may have been ignoring lately.

Tuesday

Tuesday
24°C / 13°C
Mainly sunny

Tuesday will not be much different from Monday. Temperatures will once again be in the low to mid twenties with mainly sunny skies. The wind will be gusty from the south, but it will still be a nice day. Unfortunately, that gusty wind will mean there will be a few leaves to start raking up, but that’s hardly reason to start complaining.

Wednesday

Wednesday
23°C / 14°C
Mix of sun and cloud

Another good day is in store for Wednesday. Temperatures will again be in the low to mid twenties. Skies will likely range from mainly sunny to a mix of sun and cloud. There will also be a gusty south wind, just like Tuesday.

Long Range

Long range models continue to show above-normal weather for the foreseeable future. In fact, we may see temperatures climb even higher by late this week into the weekend. This may be our last taste of summer weather, so enjoy it!

Warm & Unsettled Weather

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The weather over the next couple days will be two things: warmer than normal for this time of year and somewhat unsettled. While no major rain-makers are expected, a couple rounds of showers will make for some damper spells. Fortunately, daytime highs near 20°C will be above the seasonal 17°C through the weekend!

Friday
22°C / 12°C
Mixed skies; chance of showers or thunderstorms

Saturday
20°C / 10°C
Mixed skies; chance of showers or thunderstorms

Sunday
20°C / 10°C
Mainly sunny

Today will bring mixed skies to Winnipeg as a broad trough of low pressure works its way across the province. There will be a slight chance of showers this morning if any of the overnight activity manages to linger on and/or push far enough north, however nothing significant is expected. We’ll see mixed skies heading into the afternoon with a high near 22°C with winds tapering off to light.

The RDPS is forecasting a line of thunderstorms along the advancing cold front this afternoon.
The RDPS is forecasting a line of thunderstorms along the advancing cold front this afternoon.

Later in the afternoon the threat of showers or thunderstorms returns as a weak cold front begins slumping southwards. Severe weather doesn’t look likely, although if stronger thunderstorms manage to develop some marginally severe hail could be a possibility.[1]

Skies will clear out a bit in the evening and we’ll be left with partly cloudy skies on our way to a low of around 12°C.

Saturday will start off with just a few clouds around. We’ll warm up to around 20°C for an afternoon high with winds gradually increasing out of the west-northwest to around 20–30km/h. By mid-to-late afternoon the threat for shower or thunderstorm activity will increase as a shortwave sliding down in the northwest flow aloft begins triggering activity over Parkland Manitoba and the Interlake. That activity will slide southeastwards through the afternoon into the evening with scattered showers or thunderstorms looking fairly likely.

This map of a feature called vorticity – essentially a measure of spin – shows a potent shortwave moving across Southern Manitoba on Saturday afternoon.
This map of a feature called vorticity – essentially a measure of spin – shows a potent shortwave moving across Southern Manitoba on Saturday afternoon.

Some thunderstorms may be surprisingly strong given the relatively meagre convective indices for the day. The key will be the favourable storm-relative winds in place. Suitable turning will be in place that it’s possible — not necessarily likely, but possible — for an isolated supercell or two to develop with strong winds and large hail being the primary threats.

Skies will clear out on Saturday night as we drop to around 10°C.

Sunday will be a nice day with not a whole lot to say about it! A ridge of high pressure moving into the province will bring clear skies and relatively warm temperatures with a high near 20°C. The temperature on Sunday night will drop to around 10°C.

  1. Environment Canada considers severe hail to be 20mm or larger in diameter.  ↩

Week to End with Summer-Like Weather

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Patience will be rewarded heading towards the end of the week as above-normal temperatures[1] are poised to return to Southern Manitoba thanks to a low pressure system that will push across the Central Prairies. In addition to the warmer weather, the chance for some wet weather, possibly even thunderstorms, will make a return as well.

Warmer air is forecast to spread eastwards across the Southern Prairies over the next 48 hours.
Warmer air is forecast to spread eastwards across the Southern Prairies over the next 48 hours.
Wednesday
14°C / 3°C
Mainly cloudy & cool; clearing in the afternoon

Today will be the coolest day of the next few as we remain on the periphery of a large pool of Arctic air. Plenty of stratus cloud will persist in Winnipeg until this afternoon; afterwards we’ll see clearing skies and a high temperatures near 14°C. Another chilly night lies ahead with temperatures dropping to the 3 or 4°C mark under continued clear skies.

Thursday
20°C / 16°C
Increasing cloudiness with a breezy southerly wind

Thursday will mark our entry into warmer weather. Gusty southerly winds will develop ahead of a warm front that will gradually push eastwards through the day. Winds will peak at around 30–40km/h with the potential for gusts to around 50km/h. Much of the day looks fairly sunny which will help temperatures climb to around 20°C by late in the afternoon, but by mid-to-late afternoon clouds will noticeably begin thicken up.

The potential for thunderstorms returns Thursday night, but it’s conditional and will be mainly confined to southwestern Manitoba. Substantial mid-level instability will couple with a strong low-level jet (LLJ) in the evening to attempt to produce thunderstorms. While many severe weather parameters output by various models look fairly impressive, there are a few concerns I have with development, somewhat related to each other:

  1. Even lifting from the low-level jet, convection looks capped. If lift is strong enough to break through the cap and taps into the mid-level instability, then strong to severe storms could be possible, but…
  2. Synoptic lift looks uncertain. While the LLJ is forecast to be quite strong at 25–35kt, deeper synoptic lift looks uncertain. Some models hint at a shortwave rippling through the region on Thursday evening, which could help initiate thunderstorms if true.
The NAM is forecasting winds in excess of 40kt at 850mb over Southern Manitoba on Thursday evening.
The NAM is forecasting winds in excess of 40kt at 850mb over Southern Manitoba on Thursday evening.

If thunderstorms did manage to initiate over southwestern Manitoba, they would have a chance of becoming severe, with the main threats being large hail and strong winds. As the system pushes eastwards overnight, the chance for showers or thunderstorms will spread into the Red River Valley. The thunderstorm potential will diminish as the system moves eastwards.

With all the cloud, potential precipitation and breezy winds moving through overnight, temperatures will remain fairly mild, only dipping down to the mid-teens.

Friday
22°C / 9°C
Chance of morning showers; afternoon clearing

Friday will continue the pleasant weather. A slight chance of showers may persist into the morning from Thursday night, but skies should quickly being to clear out, leaving us with partly cloudy to mixed skies for the remainder of the day. Daytime highs will climb into the low 20’s without too much wind to worry about.

Temperatures will drop just under 10°C on Friday night under mainly clear skies.

The Weekend Ahead

The coming weekend looks great! Mostly sunny skies will dominate through the weekend with daytime highs continuing to sit in the low 20’s and overnight lows in the mid-to-high single digits. It will be a beautiful late-September weekend, so get out and enjoy it!

  1. Normal temperatures in Winnipeg for this time in September are around 18°C for high temperatures and 6°C for low temperatures.  ↩