Tag: Rain

Cool, Showery Weekend Ahead

Brad Leave a comment

An upper low crossing the Prairies this weekend will keep temperatures cool in southern Manitoba with some showers or thunderstorms likely in the days ahead.

RDPS 12-hour Precipitation Accumulation valid 00Z Saturday August 12, 2023
Rainfall will be scattered throughout southern Manitoba today as showers and thunderstorms develop over the region.

A weak low pressure system will move across southern Manitoba today, the lingering feature from the system that brought 5 to 10 mm of rain to Winnipeg yesterday evening. As this low trundles into the Red River Valley this afternoon, it will support the development of scattered showers and thunderstorms. Severe weather is unlikely; energy will be limited with only 500 to 1000 J/kg of MLCAPE and bulk shear is also low at only around 15 to 20 knots. A marginally severe thunderstorm with large hail can’t be ruled out, but much of the area will mainly see the chance of showers and shorter-lived pulse thunderstorms.

Much of the activity will taper off in the evening, but a few showers may linger into the night, supported by both a shortwave sliding across the region and a weak trough extending from southern Manitoba northwestwards into central Saskatchewan.

On Saturday, the region will continue to see mixed skies with a slight chance of showers. Much less activity is expected than on Friday; there will be few, if any, features to support and organize showers. A bit of lingering instability may be left behind, but for the most part, mixed skies with just a slight chance of an isolated shower or two is most likely.

On Sunday, another low pressure system is poised to dive southeastwards through the province, bringing a good chance of rain to many parts of southern Manitoba. Some uncertainty remains on the track, but in general areas south of a line that runs roughly from Dauphin to the Whiteshell are likely to see accumulating rain at some point from early Sunday morning through the end of the day.

Temperatures over the next three days will be steady in the 20 to 25 °C while winds will generally be on the lighter side. Winds both today and tomorrow will mainly be westerly, while the passing low will shift the winds more northerly on Sunday.

Long-Range Outlook

It’s looking like unsettled conditions will continue into next week. Monday should bring a reprieve from any wet weather, but the chance of rain will return several times through the rest of the week. Winnipeg’s daytime highs and lows will sit at near-seasonal values through next week.

Today’s seasonal daytime high in Winnipeg is 26 °C while the seasonal overnight low is 12 °C.

Severe Thunderstorm Threat Followed By More Unsettled Weather

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Hot and humid weather over southern Manitoba will lead to a thunderstorm outbreak on Tuesday afternoon. A cold front will slowly push across the region on Wednesday, bringing more showers with a risk of thunderstorms again, though severe weather is less likely. One last blast of unsettled weather will develop Thursday evening in North Dakota and spread into Manitoba overnight. By Friday, Winnipeg will see some more settled conditions.

RDPS 2m Temperature Forecast valid 21Z Tuesday June 20, 2023
It will be another hot day over the Red River Valley with highs in the 30s with dew points climbing over 20 °C.

There is a notable severe thunderstorm threat today in southern Manitoba as a hot and humid air mass continues building into the region. The main drivers of the weather today will be a warm sector trough that will arc from north-central North Dakota into the Interlake this afternoon and a cold front that is gradually shifting eastwards from the Manitoba/Saskatchewan border.

Along and east of the trough — which includes the Red River Valley — very hot and humid conditions will develop today. Daytime highs will climb into the low to mid-30s with dew points climbing up to around 20 °C. This will produce widespread humid values in the upper 30s or low 40s across much of south-central and southeast Manitoba. As this air mass cooks, it will bump up against the warm sector trough as it slowly shifts eastwards through the day.

By mid-afternoon, very significant amounts of energy for thunderstorm development will have built up in southern Manitoba. A quick summary of the afternoon’s convective parameter forecasts: MLCAPE values in the 2,000–3,000 J/kg range, bulk shear values of 25–45 knots, shear vectors aligned roughly along the convergence boundary, and STP values ≥ 1.

NSSL-WRF Forecast MLCAPE valid 21Z Tuesday June 20th, 20233km NAM Simulated Reflectivity valid 02Z Wednesday June 21, 2023
The NSSL-WRF model (left) shows clearly the axis of significant instability that develops on Tuesday afternoon. By 7PM CDT, thunderstorms will begin to develop and quickly grow into a complex of [potentially severe] thunderstorms within a couple hours (right).

The end result of all the parameters is this: thunderstorms will redevelop this afternoon and there will be numerous severe thunderstorms. Primary threats today will be very large, damaging hail and torrential rain. With so much energy to work with, it’s also likely that some thunderstorms will be able to produce damaging wind gusts. An isolated tornado or two is possible today, particularly early in the storm development later today.

Be sure to be aware of any severe weather watches or warnings issued by the Meteorological Service of Canada through the day today.

The thunderstorm activity will continue into the night, growing upscale along the trough and slowly shifting eastwards. Activity will refocus further south overnight where another disturbance riding northeastwards along the cold front, spreading more showers with the risk of thunderstorms into southern Manitoba by Wednesday morning. With the cold front further east, Winnipeg will see cloudier conditions through the day but temperatures could still be quite warm with highs in the upper 20s. Thunderstorm activity on Wednesday will be weaker overall than today, with a much lower risk of any severe-level activity.

More rain and thunderstorms is possible overnight Wednesday into Thursday as another disturbance rolls into the province along the slow-moving frontal boundary. It will support an area of nocturnal convection that will push into southern Manitoba, bringing what could be another widespread area of precipitation. There will be much less instability by this point, so little to no severe weather is likely with this final round of showers. This system will also bring cloudy skies to the region for much of Thursday with highs finally dipping back down into the mid-20s. The humidity stuck in the region will also finally begin to ease as the cold front slowly shunts southeastwards.

Long Range Outlook

More unsettled weather is likely this weekend as an upper low treks northeastwards out of the American Rockies, bringing a broad area of rain into southern Manitoba. There’s still some uncertainty associated with this system, but at this point it looks like a widespread 25 to 50 mm could be possible across many parts of southern Manitoba through a combination of rain and embedded thunderstorm activity. This system will clear out of the region to start next week, followed by another chance of showers on Monday evening as a cold front slumps into the region.

All in all quite an unsettled week ahead of us with numerous chances for showers and thunderstorms across the region. Particularly today, be sure to keep aware of the day’s thunderstorm development given the notable risk of severe weather.

Today’s seasonal daytime high in Winnipeg is 24 °C while the seasonal overnight low is 11 °C.

Seasonal Temperatures With a Chance of Showers

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Seasonal temperatures will persist in Winnipeg for a couple more days with a chance of showers as a couple disturbances pass through the region.

RDPS 300mb Height and Wind Forecast valid 18Z Saturday June 17, 2023
This small shortwave and associated jet streak (blue/purple shading) entering southwest Manitoba on Saturday is the source of much uncertainty for the day’s weather.

Temperatures will climb to a high near 20 °C today as a slow-moving front begins nudging its way into the Red River Valley. It will bring a slight chance of some showers with it, but none of them will likely be particularly intense and no widespread rain will come from this system. The cloud cover will break up a bit for the evening, then temperatures will dip into the low teens overnight.

On Saturday, some more showers are possible as an upper-level disturbance pushes across the region. There’s still some uncertainty on this one with very divergent solutions between Canadian and American weather models. The Canadian forecasts are producing an area of rain that will push across the region midday into the afternoon. The American models, on the other hand, keep it dry. Personally, I’m hoping for the dry solution for an event on the day, but it’s really a toss-up right now. Things will become much more apparent later today when it materializes well to our southwest and we can see what it’s able to start producing.

Aside from that, Winnipeg will likely see mixed to cloudy skies on Saturday with a high in the low to mid-20s. Skies will clear out overnight with temperatures dropping into the mid-teens.

On Sunday, heat will begin to build back into the region. Temperatures will climb back into the upper 20s under mainly sunny skies. Humidity levels will stay comfortable, making for a beautiful summer afternoon.

Long Range Outlook

Next week will continue the trend of warm weather with daytime highs in the low 30s gradually easing into the mid- to upper-20s.

Unlike the last bout of heat we experienced, this warmth will be the response of a deep upper trough digging southwards along the west coast. As a result, conditions will become fairly unsettled next week over the southern Prairies with several disturbances tracking through that will bring a risk of thunderstorms to the region.

The main risk should primarily stay to the west and north of southern Manitoba through the first half of the week, but stormier weather is likely in the second half of the week.

Today’s seasonal daytime high in Winnipeg is 24 °C while the seasonal overnight low is 11 °C.

Summer Warmth Arrives in Winnipeg This Week

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After a bit of an unsettled Tuesday, sunnier skies develop over southern Manitoba with high temperatures climbing into the mid-20s!

RDPS 2m Temperature Forecast valid 21Z Thursday May 11, 2023
Temperatures will climb into the mid-20s across southern Manitoba on Thursday.

Warmer weather will arrive in Winnipeg today with daytime highs climbing back to around 20 °C. A weakening upper trough over the region will provide instability for mixed skies with some scattered afternoon showers. The odd shower might end up strong enough for a couple lightning strikes, but no notable organized thunderstorm activity is likely. A few clouds will linger overnight with temperatures heading down into the low teens.

The weather over the next few days will be shaped a building upper ridge over the eastern Prairies. This will settle conditions and push warmer weather northwards. With sunny skies on Wednesday and a bit of cloud on Thursday, temperatures will climb into the mid-20s. In addition to the warmth, dew point values will hover close to 10 °C, making for very comfortable conditions.

Overnight lows will continue to dip into the 10–15 °C range at night. On Wednesday night, there will be a small chance of some showers driven by some weak instability aloft that will persist through the night.

Long Range Outlook

Cloudier conditions will move in for Friday and Saturday in southern Manitoba. A potent low pressure system will spread rain into the northern United States, but a strong deformation zone will keep a sharp cut-off to the rain south of the Canada–U.S. border. The cloud will combine with moderate northeasterly winds to send daytime highs a few degrees cooler; Winnipeg will see daytime highs near 20 °C to wrap up the week.

Sunshine will return ton Sunday as this storm system clears. Temperatures will head back into the mid-20s with the heat persisting into next week.

Today’s seasonal daytime high in Winnipeg is 18 °C while the seasonal overnight low is 4 °C.