Tag: Windy

Friday’s Surge of Heat & Humidity Leads to Unsettled Weekend

Brad

Heat & humidity will begin moving into the region today as a breezy southerly wind develops over the province, tapping into a much warmer air mass over the Northern Plains of the United States.

A potent low pressure complex developing over the western Prairies & Northern Plains will bring a thunderstorm threat back to Southern Manitoba today with the southwestern corner of the province under the threat for thunderstorms—potentially severe—this afternoon and this evening, while the Red River Valley and southeastern Manitoba seeing the threat move in this evening and into Saturday morning.

Before that, though, Winnipeg & the Red River Valley will have a fairly nice day ahead. Temperatures will soar through the morning, reaching within a degree or two of today’s high temperature of 28°C by lunch. Skies will be mixed today with cloudier conditions developing in the afternoon. Southerly winds to 30-40km/h will pick up through the day across much of Southern Manitoba, drawing moisture from the United States northwards into the province. By late afternoon, dew point values in the Red River Valley will climb to the 16-18°C range1 while in the southwest corner of the province, dew point values may reach the 20°C mark, making for very humid feeling conditions.

AWM Convective Outlook for June 24/25, 2016
AWM Convective Outlook for June 24/25, 2016
As the afternoon wears on, a leading shortwave lifting out of Montana will destabilize conditions over southern Saskatchewan and southwestern Manitoba, bringing a threat of thunderstorms to the region. There’s a slight chance that some of these thunderstorms may become severe. The threats from these storms will be:

  • Rainfall: Precipitable water values of 35-45 mm combined with storm motions of 20-30km/h will produce very intense rainfall, but the storms will be moving quickly enough that the overall rainfall accumulations will be limited.
  • Hail: With MLCAPE values in the 1500-2500 J/kg range and ample shear present, storms will likely take the form of discrete supercells early in their life cycle. These storms will be capable of producing large, damaging hail.
  • Wind: Overall, wind won’t be a widespread threat with these storms, but isolated damaging wind gusts are possible.
  • Tornadoes: The supercell thunderstorms in southeastern Saskatchewan and southwestern Manitoba will be in environments with very strong directional shear. A small chance of a tornado or two exists with these storms.

As we move into the evening, scattered showers or thunderstorms are possible over the Red River Valley while the thunderstorms closer to the SK/MB border continue onwards and grow into a larger complex of thunderstorms that will push eastwards overnight. Instability actually increases overnight as moisture continues to be pumped northwards along the low-level jet ahead of the incoming shortwave. As a result, a large area of rain and thunderstorms will likely progress eastwards overnight, reaching the Red River Valley between 3 and 6AM. These thunderstorms will present a slight risk of severe weather with primary threats of rain and large hail, with a secondary threat of damaging wind gusts.

Worth noting: if the western shortwave offering support to this system ends up slowing down, the overnight thunderstorm activity may diminish over southwestern Manitoba.

Temperatures will remain very warm on Friday night with overnight lows near 20°C in the Red River Valley.

Saturday: Muggy with Continued Thunderstorm Threat

Saturday will start with whatever convection moving through on Friday night exiting the region, and we’ll be left with very humid conditions with dew point values likely climbing to 20-21°C. Temperatures will climb towards the mid-20’s through the morning under fairly cloudy skies, but conditions will undergo a fairly significant change midday as a cold front sweeps through. The passage of this front will bring another threat of showers and thunderstorms to the region and with MLCAPE values near 1500-2000 J/kg and ample shear, these will also have bring the threat of severe weather with rainfall, winds and hail a concern.

4km NAM Dewpoint Forecast valid 15Z June 25, 2016
High dewpoint values over 20°C will be in place on Saturday morning in the Red River Valley.
Once the front passes, gusty westerly winds will usher in drier air as dew point values plummet into the single digits, bringing relief from the humidity. Skies will begin clearing as well, likely providing some afternoon/evening sunshine. Temperatures will likely top out at only 24 or 25°C, though, and a cooler night will be ahead with lows near 15°C.

Dreary End to the Weekend

Saturday night’s clear skies will be replaced by cloud on Sunday as the main upper-level low of this whole weather system moves through the region. It will bring showers to much of Southern Manitoba with most of the activity through the morning hours and then tapering off through the afternoon. Temperatures will be much cooler with a high near 17 or 18°C and strong northwesterly winds of 40 gusting 60 km/h picking up by the end of the morning.

The winds will taper off overnight as the valley heads to a low near 11°C.

Winnipeg’s seasonal daytime high is currently 24°C while the seasonal overnight low is 12°C.

  1. At a dew point of 16-18°C, it begins to feel mildly muggy. ↩

A Couple More Cool Days Before We Heat Up

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We’ll have a couple days of cool weather before an upper ridge builds in, bringing hot & humid weather to southern Manitoba in the second half of the week. The arrival of the heat and humidity is also expected to bring our first significant risk of severe thunderstorms this year.

A cool northerly flow will be in place over southern Manitoba on Monday
A cool northerly flow will be in place over southern Manitoba on Monday

This Week

Today will remain on the cool side as a surface high to our north-west pumps cool air into southern Manitoba. Some cloud cover is expected in southern Manitoba during the morning as an upper disturbance moves through, but skies should clear by the afternoon. Daytime highs will be in the upper teens with gusty north winds at 40 km/h gusting to 60 km/h.

Tuesday will remain cool as we remain under the influence of that surface high. Temperatures will once again be in the upper teens, although some areas in western Manitoba may reach the low twenties. Skies are expected to be mainly sunny and winds will be breezy from the north.

Warmer weather will begin to move into southern Manitoba on Wednesday as the surface high moves off to the east. A southerly flow will be in place over southern Manitoba, helping to bring warmer air into the region and push daytime highs into the mid twenties over the Red River Valley and the upper twenties over western Manitoba. There will likely be a risk of severe thunderstorms in eastern Saskatchewan on Wednesday and that may spill over into western Manitoba. Depending on how conditions develop, the thunderstorm risk may extend across all of southern Manitoba on Wednesday night as storms from Wednesday evening move east with time. A westerly steering flow and a strong southerly low-level jet would tend to favour easterly or south-easterly storm motions, which would help steer storms toward the Red River Valley during the overnight period. More details on Wednesday’s potential thunderstorm risk will be available as the week progresses.

Long Range

The long range forecast suggests a hot, but unsettled pattern, will be in place for southern Manitoba from late this week into the weekend. An upper ridge will be centred over southern Manitoba during this time period, but we are expected to remain at the top of this ridge, putting us along the storm track. The influx of warm, humid air due to the southerly flow in this ridge combined with the moderate to strong flow with the jet stream aloft should favour numerous thunderstorm chances during the Wednesday-Monday period. The nature of the thunderstorm threat remains quite unclear, but at least one or two severe events seems probable at this time. An upper trough is expected to approach either late this weekend or next week, which will push out this hot/humid air mass.

A Stretch of Beautiful Summer Weather

Brad

Winnipeg will see plenty of sun and warmth as the first deep southerly flow of the year develops this week, advecting warm and increasingly humid air northwards from the Great Plains of the United States into Manitoba.

The coming days will be bring beautiful summer weather with plenty of sunshine and temperatures soaring into the mid-20's. This afternoon will also bring breezy southerly winds to around 30-40km/h. We'll see just a few clouds today as a weak disturbance moving into Manitoba from the western Prairies slowly falls apart.

RDPS Temperature Forecast valid Thursday Afternoon
The RDPS shows warm summer-like temepratures across the Prairies on Thursday.

Thursday and Friday will both be sunnier days with winds out of the south at 20-30km/h. Thursday will be the windier of the two with gusts in the 40-50km/h range possible, while Friday will see winds more steady and a bit lighter. For both days, the high will be near 26 or 27°C.

Nights will be much milder than we've seen lately with overnight lows in the 12-15°C range.

Of note, and a significant change from what we've seen so far this year, is that this prolonged period of southerly winds will finally bring some more humid air into the region as moisture from the Great Plains of the United States. By the end of Friday, dewpoints will have climbed from near 0°C into the upper single digits. While we won't notice a significant difference in how it feels, it will certainly alleviate some of the moisture stress for plants which could help improve the fire danger in the region.

Long Range: 2016's First Humid Days?

For the weekend, the weather will continue distinctly summery with high temperatures climbing into the upper 20's. Along with the continued warmth, those southerly winds will continue to push moisture northwards and begin pushing dewpoint values towards something that may actually begin to feel humid. By the end of Saturday, it is forecast that the dewpoint will climb to around 12-13°C which is a fairly typical summer value for the region. On Sunday, however, a surge of humidity is expected to push into Manitoba, bringing dewpoint values into the 15-17°C range, which will begin to feel a bit humid when combined with a high near 29°C.

GFS Surface Dewpoint Forecast valid Sunday Evening
The GFS shows clearly this weekend’s stream of humidity from the Gulf of Mexico northwards through the Great Plains into Southern Manitoba.

With the humidity will also come unsettled weather. It's far to early to get into many specifics, but beginning on Sunday afternoon, the chance for thunderstorms will make an appearance across Southern Manitoba. Early indications are that there may be a slight chance for severe thunderstorms with a primary threat of severe hail. We'll be sure to keep an eye on things as they develop and provide a more in-depth outlook in our Friday post.

Winnipeg’s seasonal daytime high is currently 20°C while the seasonal overnight low is 6°C.

Flurries Start Off A Cool Weekend

Brad

Today will start off with flurries moving through the Red River Valley, setting the stage for a snap of cool weather that will bring temperatures well below seasonal. While temperatures will rebound slowly through the weekend, it will hardly be beautiful spring weather.

Today will be a rude awakening for many, as cold temperatures combine with a weak disturbance rolling through the region to produce widespread light flurry activity through the Red River Valley. Some places might get lucky enough to see things change over to scattered showers briefly this afternoon, but for the most part, expect some light snow for much of the morning and into the afternoon. Fortunately, the snow won't really stick and no accumulation is expected.

In addition to the snow, the winds will continue to be strong out of the northwest at 40 gusting 60km/h with a daytime high that just barely gets to 5°C.1 Temperatures will dip to near the -4°C mark tonight with clearing skies. Near the core of Winnipeg it's not as likely that there will be a hard freeze, but certainly near the outer edges of the city and into the rural areas a significant freeze is likely so you may want to take precautions if you've any sensitive plants outside already.

GDPS Forecast 850mb Temperature Anomaly
The 850mb temperature anomaly forecast shows a large core of below-seasonal (blue) temperatures over Manitoba today.

Saturday will finally bring out the sun in Winnipeg, but it will continue to be chilly with a daytime high of 9°C under mainly sunny skies. Winds will continue out of the northwest, but be slightly weaker at 20km/h or so. Expect a low near the freezing mark on Saturday night with partly cloudy skies and light winds.

Sunday will see another disturbance moving through the province in the northwest flow. More cloud will move into Winnipeg alongside slightly warmer temperatures; daytime highs are expected to climb into the mid-teens! A band of showers will likely move through in the afternoon, bringing a decent chance of precipitation to most areas in the Red River Valley. Winds will vary through the Red River Valley from light to around 30km/h. Expect a low on Sunday night near 3°C with partly cloudy skies.

Long Range: Climbing To Seasonal

Looking ahead to the start of next week, it appears that temperatures will make a continued climb back towards seasonal, however the with a stubborn upper trough refusing to leave the area, that could end up taking longer than expected. Conditions aren't expected to be too bad with a good mix of sun and cloud and highs in the mid- to upper-teens. There will be a slight chance of showers.

Winnipeg’s seasonal daytime high is currently 19°C while the seasonal overnight low is 5°C.

  1. Nearly 15°C below normal for daytime highs right now in Winnipeg. ↩