Tag: Thunderstorms

Weekend to Bring A Break From The Heat

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Slightly cooler weather will move in this weekend behind a low pressure system forecast to move through tonight and tomorrow. In addition to the cooler temperatures, this system will bring a chance of rain and thunderstorms to the Red River Valley.

Tonight & Tomorrow

Friday

27°C / 18°C
Increasingly cloudy; risk of a thunderstorm late in the afternoon into the evening. Humid.

We’ll see gradually increasing cloud today as the surface trough associated with a low pressure system pushing into the northern Interlake approaches. There may be some ongoing thunderstorm activity along the trough this morning as it pushes through SW Manitoba and that threat will move eastwards into the Red River Valley by the late afternoon or early evening. A southerly wind ahead of the trough coupled with a capping inversion will draw moisture northwards once again and trap it near the surface, making for another hot, sticky day here in Winnipeg. Our high temperature will only climb to around 27 or 28°C, though, thanks to the increasing cloudiness through the day. That hot, humid weather will bring the threat for thunderstorms – potentially severe – late in the afternoon into the evening hours. At this point, it seems like somewhere between 8PM and 11PM seems like the most likely time for seeing any potential storm activity. After that we’ll see our temperature drop to around 18°C under a partly cloudy sky.

Saturday

25°C / 12°C
Becoming cloudy, good chance of showers or thundershowers. Humid again.

Saturday will be another humid day as we remain in the moist air mass ahead of the cold front. We’ll see a fairly good chance of showers or thundershowers beginning later in the morning and through the afternoon. Skies will start off as a mix of sun and cloud but should become fairly cloudy in the afternoon as things become more unstable with the approaching cold front. We’ll see a high of around 25°C which will mark the last day in our hot, muggy air mass. The threat for showers or thunderstorms will persist until the cold front passes.

500mb Winds for Saturday Afternoon

500mb winds forecast by the NAM show an intense upper-level low pushing into Southern Manitoba which may be the catalyst for showers and thunderstorms on Saturday afternoon and evening.

The cold front will push through overnight, bringing northwesterly winds that will clear out much of the moisture and drop us to a comparatively cool 12°C for an overnight low with clearing skies.

Sunday & Holiday Monday

Sunday

23°C / 8°C
Sunny. Cooler and much less humid.
Monday

25°C / 13°C
Sunny and warm.

Sunday and Labour Day Monday look absolutely beautiful. Sunday will be slightly cool with a high of only around 23°C and lead into a chilly night with a low dropping into the single digits bottoming out around 8°C. The heat starts to return on Monday with sunny skies continuing as we climb to a mild 25°C.

The Trend Next Week

Looking further into the week, it looks fairly nice overall as the upper ridge begins rebounding back northwards into the Prairies. Highs will push back into the upper 20’s with humidity staying fairly low until late in the week. Things look fairly dry through the first half of the week, with a few weak disturbances bringing the threat for isolated-to-scattered thunderstorms late in the week. For the most part, though, it looks to be a beautiful, warm week. Summer may be late, but it doesn’t look like it’s going anywhere soon!

Hot Weather Continues

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The hot weather in place over the Red River Valley will stick around through the rest of the week, although a few more weak disturbances will bring in a little more cloud alongside the risk of a few showers or thunderstorms.

Wednesday

31°C / 18°C
A mix of sun and cloud. Humid.
Thursday

28°C / 18°C
A mix of sun and cloud. Humid. Slight chance a shower or thunderstorm.
Friday

27°C / 17°C
Mainly sunny. Chance showers or thunderstorms Friday night.

Today

We’ll see another hot and humid day today as temperatures climb into the low 30’s again with dew points hovering around 19–20°C. No precipitation is expected although we’ll see a mix of sun and cloud associated with a weak frontal system that wills be in the area.

Thursday

Tomorrow will be an interesting day; at this point it looks like we’ll see a fair amount of cloud in the morning before clearing out for the afternoon as an area of showers and thunderstorms moves across North Dakota and perhaps portions of the southern Red River Valley. Should this system push further north, there would be a slight chance of showers in the morning here in Winnipeg, but at this point I think that we’ll stay dry. Things will be pleasant in the afternoon as we climb to a high around 28°C before a weak upper-level cold front pushes into the Red River Valley. As it sweeps through in the evening, there will be a chance of some showers or thunderstorms pushing into the Red River Valley alongside it. Most regions in the RRV will see a chance of a shower or thunderstorm in the evening and overnight hours. Things will move out overnight as we drop to a low around 18°C.

Friday

Friday will be a beautiful day with mainly sunny skies and a high around 27°C. The humidity will drop off through the day as we heat up and are able to mix some of the remaining moisture near the surface out. There’s little threat of precipitation until the evening and overnight hours as low-pressure system pushes into Southern Manitoba, where thunderstorms will be possible with this system along a trough that will push through the Red River Valley. Depending on how things set up, there may be a slight risk of a severe thunderstorm with this system, so we’ll be sure to keep an eye on how things are setting up.

The Long Weekend

A preliminary look ahead through the long weekend looks beautiful. Skies should clear on Saturday morning and after that, it looks like nothing but sun, sun and more sun all the way through Monday. Highs look to be in the mid-to-upper 20’s, generally between 25–28°C with overnight lows dipping down to around the 12–13°C mark thanks to significantly less humidity in the air mass behind Friday night’s low pressure system.

Unsettled Weather Pattern Developing

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After a couple slightly cooler days across Southern Manitoba the heat is set to return as a southerly flow develops ahead of a upper trough pushing towards the Rocky Mountains. Unlike the potent upper ridge of earlier this week, this southerly flow will be peppered with disturbances ejecting northeastwards out of the west coast trough and we’ll see substantially more unsettled weather over the next week or so.

Today

Friday

30°C / 20°C
Sunny & increasingly windy. Chance of thunderstorms & increasing humidty overnight.

We’ll today start off pleasantly as we head towards a high of about 30°C, however by midday the winds will begin pickup up out of the south and will likely reach 40–50km/h with gusts as high as 70km/h by the end of the day, making it not quite as pleasant as 30°C can be. We’ll see a mix of sun and cloud as well as some mid-level cloud streams up from the southwest through the day. Fortunately it looks like the worst of the humidity will stay off to our south for the day and, with dewpoints only in the low teens, will help the day be a little more comfortable.

There will be a chance of thunderstorms overnight into the morning hours on Saturday though as the first of many impulses lifts northeastwards into Southern Manitoba, dragging up with it substantial amounts of humidity. Overnight we should see our dew point climb to nearly 20°C, which means we’ll only see our overnight low dip to close to that mark[1]. Regarding the thunderstorms, at this point it looks like the greatest threat for any activity will be over SW Manitoba then arcing NE through the Interlake region. There will be a chance of a thunderstorm through much of the Red River Valley, with the greatest risk at the north end – Winnipeg in particular could end up seeing the bulk of the action if things end up just a bit further south than currently forecast – and a decreasing risk towards the U.S. border. These storms are not expected to be severe, however given the ample moisture that they will be feeding off of, any storms that develop could produce substantial amounts of rainfall in short periods of time.

Saturday

Saturday

32°C / 18°C
A mix of sun and cloud; risk of thunderstorms in the morning and then the afternoon.

Saturday will start off cloudy, potentially with showers or thunderstorms in the region, and then begin gradually clearing. It will be very humid in the Red River Valley, with dew points in the low 20’s. We’ll climb towards a high of around 32°C which, with the humidty, will feel much more like 37–40°C. In the afternoon a sharp dryline[2] will begin working it’s way eastwards into the RRV associated with drier, westerly winds.

Thunderstorms are possible by late afternoon, but the exact location of them will depend on the entire synoptic setup and the placement of the dryline, which will be the feature that the storms will develop along. At this point, it appears that the western half of the RRV will be safe with an increasing risk through Winnipeg & the central RRV to a much greater chance over the eastern RRV into Sprague & the Whiteshell. These storms could easily become severe given the ample heating and surface moisture, 500mb jet core in the area providing 30–40kt of bulk shear, as well as a defined trigger in the dryline.

The storm potential does seem fairly dependant on the exact placement and strength of the dryline; if it doesn’t evolve to be strong enough or hangs back too long or blows through too early, then there will be almost no chance of any storms on Saturday. If storms develop, the main threats (particularly if they become severe) will be torrential rain and large hail. A tornado could not be ruled out either, but the flow may not be strong enough to support/sustain one. Strong winds would not be a widespread concern at this point.

And of course, since there has to be one more wrinkle in things, this will all be dependant on mid-level temperatures. The Canadian long-range model (GDPS) is forecasting cooler air at the mid-levels pushing over the RRV on Saturday afternoon, which would help destabilize things; if temperatures remain warmer at the mid-levels then we would likely remained capped and see have no thunderstorm activity. A lot of words for a conditional threat, but it could be a significant severe thunderstorm day for the Red River Valley and the Whiteshell, so I thought we should go over some of the possibilities and unknowns!

Sunday

Sunday

32°C / 18°C
Mainly sunny.

Sunday will be a very nice day with mainly sunny skies, light winds, and a high near 32°C. There will be little to no chance of any precipitation; at this point it looks like there may be a marginal chance of an isolated thunderstorm near the U.S. border in the Red River Valley, but even that is pretty unlikely. Humidity will actually be quite comfortable as well, with dew points in the low teens. Probably the nicest day of the weekend, so get out there and enjoy it!

Next Week

Without spending too many words on it, next week continues the warm trend with highs looking to be near 30°C much of the week; we’ll also see multiple disturbances move through bringing showers and thunderstorm threats to Southern Manitoba. It will likely be more pleasant than not, though, and our late-arriving summer will certainly continue!

  1. The dewpoint is often a good measure of what overnight lows will be as the temperature will often – but not always – dip just a couple degrees below it. When the dew point is high, such as the upper teens or low 20’s, often the temperature will only approach the dew point temperature, not dip below it.  ↩
  2. A dryline is similar conceptually to a warm or cold front, but instead of being warmer or colder on one side of the front, it’s more humid ahead of the dryline and substantially drier behind it.  ↩

Above-Normal Temperatures Continue

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The above-normal temperature streak we’ve seen the past few days will continue through the rest of the week – albiet at a slightly moderated level – until a more unsettled pattern develops for the weekend.

Today & Tomorrow

Wednesday

26°C / 11°C
Mainly sunny.
Thursday

26°C / 13°C
Sunny.

We’ll see mainly sunny skies the next couple days as a ridge of high pressure slides across the province in the wake of the cold front that pushed through last night.

This ridge of high pressure will bring a break from the 30°C+ weather we’ve had the past couple days, bringing us back down to closer-to-seasonal temperatures in the mid–20’s. We should reach about 26°C each day which is still a couple degrees warmer than the seasonal average of 24°C for this time of year. The evenings will be quite cool, generally near 10–12°C although temperatures could potentially dip into the single-digits tonight in some areas.

Friday

Friday

27°C / 17°C
A mix of sun and cloud; slight chance of showers or thunderstorms.

We’ll see a regime change come Friday as a leading impulse approaches the province ahead of a developing long-wave upper trough over the west coast. A southerly flow will redevelop ahead of this impulse pushing moisture northwards out of the Northern Plains back into Southern Manitoba; as such, we’ll see a noticable increase in humidity as temperatures climb to around 26–28°C.

Precipitation is a bit of a wildcard at this point; some models bring a wide area of rain and thundershowers into the Red River Valley in the morning and persisting through much of the day until the impulse moves into NW Ontario while others keep much of the rain north of the RRV in the Interlake and bring thunderstorms in during the evening hours.

I think that most of the precipitation will push north of the city, but I certainly can’t rule it out at this point. We’ll definitely see a mix of sun and clouds, though. It looks like a chance for thunderstorms will persist through much of the evening and into the overnight period as well.

Long-Range Outlook

This weekend we’ll see warm, humid and generally unsettled weekend ahead with showers and thunderstorms likely Saturday & Sunday in Southern Manitoba.

NAEFS 8-14 Day Outlook initialized 2013-08-20 12Z

The NAEFS 8–14 day outlook shows slightly above-normal temperatures persisting in the 1–2 week timeframe.

Looking to next week, we will continue to see above-normal temperatures as a slack or southerly flow persists. We’ll also see dew points in the high teens making it feel relatively humid as well. After a month of below-normal temperatures, it looks as if we get to enjoy a late summer after all!