Tag: Thunderstorms

It’s Going to Be Wet Somewhere

Brad Leave a comment

A muggy and increasingly unstable air mass will bring heavy showers and thunderstorms to Southern Manitoba this weekend; the “where” is nigh-impossible to predict.

The last few days has seen increasingly warm and humid air building into the Southern Prairies and today will mark the transition in Southern Manitoba into the new air mass. Unfortunately, the large-scale weather pattern will be very slow-moving and result in several days of showers which, thanks to the ample humidity, will certainly be very heavy at time.

The GDPS is forecasting over 100mm of rain through Manitoba with the upcoming system. We probably won't see that much. Probably.
The GDPS is forecasting over 100mm of rain through Manitoba with the upcoming system. We probably won’t see that much. Probably.

Due to the disorganized nature of the showers, it’s impossible to say where exactly is going to see the most rain; that will only become clear as events unfold and each successive round of showers develops. Overall rainfall totals will fall into a huge range; some places may see only 5-10mm or less by the end of the weekend, while others may see anywhere from 50-100mm…or more?

We’ll go day by day and outline the most likely scenarios and what you can generally expect. Due to the high water levels through much of Southern Manitoba, we’ll be a little generous with our “slight risk severe” area due to sensitivity to rainfall (especially large quantities in short duration). We’ll make a small note on our convective outlooks to highlight this as well.

Friday: Heavy Rain in SW Manitoba

Friday
26°C / 18°C
Mixed skies. Thunderstorms likely in the afternoon and overnight. Muggy.

Today’s main threat area will be southwest Manitoba where a combination of the remnants of thunderstorm activity from overnight will be moving through this morning and more thunderstorm activity will develop this afternoon and spread eastwards.

This morning will bring two possible areas of showers, the first over southwestern Manitoba as the remnants of the overnight storms in Saskatchewan lift north-northeastwards and the second being a slight chance of some shower or thundershower activity in the Red River Valley.

Skies will be mixed through the day as we head to a high of around 26°C as southerly winds bring in significantly more humid air; dew point values will climb above 20°C through the afternoon, making it feel positively muggy out there.

Thunderstorm outlook for June 27 & 28, 2014 for 1PM CDT through 7AM CDT.
Thunderstorm outlook for June 27 & 28, 2014 for 1PM CDT through 7AM CDT.

Thunderstorms will redevelop this afternoon over SW Manitoba and spread eastwards through the evening. The main threat from the thunderstorms today will be heavy rain thanks to elevated precipitable water values and likely slow storm motion. Back-building thunderstorms are entirely possible too, which would result in very local areas seeing torrential rains and flash flooding. Marginally severe hail is possible, but the threat would likely be limited to the earlier storms in the day. Other than that, little severe weather is expected. There is a slight chance of funnel clouds over SW portions of the province thanks to relatively high vorticity values ejecting from the base of the incoming upper-level trough and somewhat favourable low-level winds, but conditions don’t look favourable for the development of tornadoes.

The thunderstorm activity will expand into heavy shower activity as well overnight as things push eastwards and northwards. Rainfall totals will be highly variable, with some places seeing nothing and others seeing potentially more than 50mm. The heavy rain concern will shift into the Red River Valley for the overnight period. The low will be around 18°C.

Saturday: Wet Weather

Friday
25°C / 18°C
Cloudy with showers or thunderstorms, heavy at times.

Saturday looks to be the wettest day as a low pressure system lifts northwards out of North Dakota into Southern Manitoba, spreading showers throughout much of the southern portions of the province.

The break between tonight’s convection and Saturday’s weather will be short lived as showers — perhaps with some embedded thunderstorms — lift northwards out of the Dakotas into Southern Manitoba. The showers or thunderstorms will be heavy at times and will likely not taper off until closer to the evening. Rainfall totals will wind up somewhere between 10mm and 50mm, highly variable across the region.

The clouds will begin to scatter out overnight, although complete clearing isn’t likely until Sunday. The low will be near 18°C.

Sunday: A Reprieve

Friday
25°C / 14°C
We’ll see the sun!

Sunday will provide a reprieve from the drenching of the first half of the weekend. The rain activity will remain further north through the northern Interlake and regions adjacent, while further south we see the sun finally make an appearance. Things look dry through the day, although cloud and showers may push through Southern Manitoba through the night as a trough rotates through the region on the back-side of the main low pressure centre.

Winds will be breezy out of the west or southwest on Sunday at around 30-40km/h with gusts to 50-60km/h on top of that. The high will be near 25°C and the overnight low near 14°C.

Cooler Weather Returns for Next Week

Temperatures will return to slightly below normal as cooler air begins to filter southwards on the back-side of the low. Daytime highs will generally be in the low-to-mid 20’s with little chance of rain through the first half of the week.

Warmer, Muggier, Unsettled Weather Coming Up

Brad Leave a comment

Temperatures will be on their way up as a warmer, more humid air mass begins moving in from the south, but ample cloud will keep sunshine relegated to “rare resource” status.

The cooler weather of the first half of the week is on it’s way out as a broad trough pushes across the Prairies. A southerly flow will spread through Saskatchewan and Manitoba today which will begin tapping into both warmer and more humid air pushing northwards through the American Plains.

The Canadian forecast model shows the muggy air expected to move in by Friday.
The Canadian forecast model shows the muggy air expected to move in by Friday.

The warmer and more humid air will, unfortunately, also result in more unsettled weather bringing plenty of cloud to the region. Multiple disturbances tracking into the region by week’s end will also result in the return of thunderstorm activity.

Wednesday
20°C / 14°C
Mostly cloudy with a chance of midday showers. Clearing overnight.

Thursday
25°C / 16°C
Increasing cloudiness in the afternoon. Chance of showers overnight.

Friday
26°C / 17°C
Mainly cloudy with showers or thunderstorms.

Another Cool, Cloudy Day

Today will be cool and mostly cloudy through much of the Red River Valley. A few sunny breaks may develop this morning, however with daytime heating more clouds will likely be generated to take their place. There is a slight chance of some showers in Winnipeg and the rest of the Red River Valley beginning late this morning through the afternoon, but anything that develops looks to be fairly light. The high today will be around 5°C below normal at 20°C.[1] Winds will gradually shift from northeasterly this morning to southeasterly by the end of the day, remaining relatively light throughout.

Skies should clear out a fair amount on Wednesday night as temperatures dip to a low near 14°C.

Warmer, Unsettled Weather Moves In

Thursday will be the transition day for the Red River Valley into a warmer, more humid air mass. The day will likely start off mostly sunny – or perhaps a high overcast – with winds out of the southeast increasing to 20-30km/h. The temperature should reach around 26°C, however more notable will the rising dew point[2] which should reach around 17°C by the end of the day. While not too high, the extra humidity will definitely be noticeable by the evening.

Total precipitation forecast by the GDPS for Thursday evening to Friday morning.
Total precipitation forecast by the GDPS for Thursday evening to Friday morning.

In addition to the rising humidity, cloud cover will spread into the Red River Valley from as a trough works its way into southwestern Manitoba. Showers and thunderstorms will be likely over southeastern Saskatchewan and southwestern Manitoba late in the afternoon and into the evening. Although it appears that the worst – and more likely to be severe – weather will remain in Montana and North Dakota, an isolated severe thunderstorm cannot be ruled out, particularly in SE Saskatchewan.

The afternoon storm activity will weaken after sunset but likely continue through the night pushing eastwards and northwards. There will be a fairly good chance of some shower or thundershower activity tomorrow night through most of the Red River Valley; no severe weather is expected at this point. Thanks to the more humid air, the overnight low will sit around 17°C.

Stormy Friday

Friday will mark a return to wetter weather as a low pressure system lifts northwards out of North Dakota through the Red River Valley, bringing with it a surge of warm, muggy air. Temperatures will climb into the high 20’s – likely around 26 or 27°C – while the dew point rises to around 21 or 22°C, making it feel very muggy.

Thursday’s overnight activity may be lingering in the morning, but it looks quite likely that things will become unstable late in the morning or early in the afternoon again, bringing more shower and thunderstorm activity. It’s still a little early to make very specific predictions, but if things pan out the way it looks now, there would be a very slight chance of severe thunderstorms in the Red River Valley with the main threats being torrential rain causing flash flooding[3] and large hail. We’ll be refining our convective outlook closer to the event since small changes between now and then – particularly with the night-time storms – can dramatically alter the forecast.

Friday night will be cloudier than not with an overnight low of 17°C. It looks fairly likely that a line of thunderstorms will develop through North Dakota along a weak cold front and track northeastwards through the overnight period. At this point it looks like that system will continue to bring a risk of thunderstorms to the Red River Valley through much of the night, but the best support for severe weather looks to remain in North Dakota/Minnesota.

Unsettled Weekend

The unsettled weather will continue through the weekend as yet another upper low begins building into the Prairies (the third in as many weeks). Saturday will likely see showers and thundershowers to the east and north of the Red River Valley to start the day. Much of the day may end up being fairly pleasant, so if that materializes get out and enjoy it!

A shortwave is forecast to move across the province on Saturday night, likely bringing another outbreak of thunderstorm activity. Severe weather may be possible.

Sunday looks to be a nice day, with the sun likely finally making an appearance and a high near the mid-20’s. The humid air should be off into Ontario by Sunday, so it will likely be quite a comfortable afternoon here in the Red River Valley.

  1. Unless a little more sun develops, then we may see 21 or even 22°C before showers take over.  ↩
  2. Dew point is a measure of how much water is in the air. Compared to relative humidity, it’s a more consistent representation of how humid it is.  ↩
  3. Which wouldn’t be particularly difficult, given the high water levels already in place.  ↩

More Unsettled Weather

Brad Leave a comment

Although nothing as notable as this past weekend’s rain event is in store, unsettled weather returns for the second half of the week.

Another sizeable low pressure system is making it’s wet presence felt, but this time the hardest hit area will be Southern Alberta where some portions in the foothills may receive as much as 200mm of rain this week. This system will slowly lumber eastwards through the next few days, slowly weakening as it does so but still producing thunderstorms and showers as it goes.

Wednesday: Severe Thunderstorm Risk for Extreme SW Manitoba

Wednesday
25°C / 13°C
More cloud than sun. Warm & breezy.

Winnipeg will see fairly pleasant weather today with mixed skies, likely leaning towards more cloud than sun, and a high near 25°C with a fairly stiff easterly wind at 30-40km/h thanks to a surface trough building southeastwards through North Dakota.

The main upper low, the heart of this large disturbance, will gradually edge eastwards through the day and will trigger thunderstorms, with some severe storms possible, through portions of southern Saskatchewan and southwestern Manitoba. Shower activity will start off the day in much of Southern Saskatchewan, but the southeast portion of the province will likely see things destabilize enough through the day that thunderstorms are likely by mid-to-late afternoon. The storm activity is most likely to initiate through western North Dakota and then build north/northwestward along the surface trough into SE Saskatchewan and into extreme SW Manitoba through the early evening.

There is an organized threat of severe weather with these storms; we’ve gone with a slight risk due to almost every severe weather parameter looking fairly good except lacking in some subtle way. The main threats will be strong winds and large hail, especially out of any storms that develop early and are sustained as discrete supercells. If the storms develop into a cohesive line, the severe threat will be diminished, although non-zero. There will be a very slight chance for tornadoes thanks to excellent low-level shear, low cloud bases, and a vorticity rich environment being advected eastwards by the upper-level low.

Today will bring a slight risk of severe thunderstorms into SE Saskatchewan and SW Manitoba.
Today will bring a slight risk of severe thunderstorms into SE Saskatchewan and SW Manitoba.

The severe storm threat will push eastwards into the Virden & Melita regions of Manitoba in the early evening with the main threats being strong winds and large hail. It does look like the tornado threat should be restricted to the Saskatchewan side of the border. Southwest Manitoba is in for quite a soaking overnight as the storms expand into an area of convectively driven rain; around 15-20mm is likely for most areas south of the Trans-Canada Highway and west of the Red River Valley (RRV), with as much as 40-50mm possible in areas that see thunderstorm activity as well.

As the area of showers pushes eastwards, it will gradually weaken into an area of showers with possible embedded thundershowers. It looks to reach Winnipeg by Thursday morning.

Thursday: Back to Wet Weather

Thursday
23°C / 14°C
Periods of rain. Around 10mm.

Thursday will be a cloudy day with a high near 23°C. Shower activity will be in the region in the morning and lift off to the northwest, however while that happens a new batch of rain will be develop to our south and lift northwards through the RRV. Around 10mm seems most likely through the day across most of the region, although if heavier shower activity ends up developing we may see closer to 15mm here in Winnipeg.

The shower activity will taper off on Thursday evening as it all lifts northwestwards into the Interlake and Parkland regions of the province. Winnipeg will see some clear breaks and a low near 14°C.

Friday: Cold Low Showers

Friday
23°C / 14°C
Mixed skies; showers or thundershowers developing midday.

Friday will see us underneath the upper-level low which essentially means that there will be a bunch of cold air high up in the atmosphere. With mixed skies, we’ll see temperatures increase towards our high of 23°C fairly quickly through the morning. By mid-day, we’ll likely have hit our high temperature and the atmosphere will become quite unstable. Expect widespread shower and thundershower activity through the Red River Vally. Rainfall amounts will be highly variable and dependant on how many showers any one spot sees and how fast things move along.

Overnight, the shower activity will consolidate to right around the upper low on Friday night as it drifts through our region and into Minnesota. The temperature in Winnipeg will drop to around 14°C.

Fairly Normal Start to the Week

Brad Leave a comment

This week will start out with fairly normal conditions for early June with a chance for rain, and moderate temperatures.

Monday will be a nice day in southern Manitoba
Monday will be a nice day in southern Manitoba

Monday

Monday
22°C / 13°C
Mainly sunny

Today may start out with a bit of rain in the morning as a piece of upper-level energy swings through but skies should quickly clear, making for a pleasant day. Any rain that does fall in the morning will be light, so it won’t be a big deal. By the afternoon we should see mainly sunny skies with temperatures in the low twenties and light winds.

Tuesday

Tuesday
23°C / 10°C
Chance of showers or thundershowers

Tuesday will see the chance for showers and thundershowers in the Red River Valley and south-eastern Manitoba ahead of an approaching trough. Any thundershowers that develop will present the risk of small hail and gusty winds. For those areas that miss out on the showers and thundershowers, it will be a nice day with temperatures in the low twenties and a breezy south-west wind.

Wednesday

Wednesday
19°C / 5°C
Mix of sun and cloud

A cold front will blow through southern Manitoba early Wednesday morning, setting us up for a slightly cooler day. Highs on Wednesday will be in the upper teens in most areas (perhaps a few readings in the low twenties), with skies being a mix of sun and cloud by the afternoon. The wind will be breezy and from the north.

Long Range

The long range forecast suggests we’ll continue to see normalish weather for the foreseeable future. That means high temperatures in the low to mid twenties and the frequent chance for rain or thunderstorms (albeit generally of the non-severe variety).