Tag: Rain

Just enough time to mow the grass.

Brad Leave a comment

Enjoy the sun today and tomorrow because guess what, more rain is on the way.


June 3, 2011 Hand-Analysis of 12Z Sounding Data; Black lines are heights, coloured lines are θw values.

The broken record keeps on repeating in Winnipeg as rain gives way to sun gives way to rain with just enough time to mow the grass in between.  With the system that brought numerous damaging storms across Southern Manitoba yesterday moving out, the upper flow aligns itself to place the Southern Prairies directly along the main storm track.


Convective outlook for June 3, 2011.

Little significant weather is expected in Southern Manitoba today, with only the slight chance of a thundershower or two over the Parkland areas, mainly in the northern Minnedosa and Dauphin regions.  Sunny skies will prevail through the evening for areas in the Red River Valley and east before a few clouds move in overnight.  Get out there and enjoy the beautiful weather!


24hr. cumulative precipitation valid 12Z Sunday 5 June from the 12Z 3 June GEMREG; my personal opinion is that it drags the precipitation a little too far south across the Prairies and that the streak through Southern Manitoba will likely be further north.

Things change by tomorrow evening, though.  A new system currently moving into the Prairies from the Yukon Territory will arrive in the Southern Prairies by tomorrow afternoon and into the Red River Valley by tomorrow evening.  This system will produce a lengthy trail of precipitation, however it’s north-to-south width looks fairly narrow.  The exact position of this shortwave will determine where precisely the rain will fall, although all indications currently point to another 2-4mm of rain pushing through the Winnipeg/Gimli/Selkirk/Whiteshell areas with lesser amounts further south.

This precipitation looks to clear out by Monday morning, leaving behind general instability through the region due to an elongated surface trough hanging back from the main system.

The sun will then come out (hopefully) in full force Monday afternoon and Tuesday morning, before cloud moves back in on Tuesday afternoon ahead of yet another low pressure system.


12hr. cumulative precipitation valid 12Z Wed 8 June from the 12Z Fri 3 June GEM-GLB

This third system within a week will push in on Tuesday evening with a warm front positioned just south of the international border, draped west-to-east across North Daktoa.  Some light rain with the risk of elevated thunderstorms riding over the warm front with push into our area by Tuesday evening before developing into a large area of moderate rain overnight.  It looks to rain through Wednesday and most of Thursday night before tapering off on Thursday morning.

This system is still a ways off, so we’ll fire off another blog post in a couple days with some more details on that one.  We’ll update Sunday’s system right in the comments here.

Do you have any stories or pictures from the storms yesterday?  Feel free to leave them in the comments or fire a tweet off to our official Twitter account, @WeatherInThePeg.

Showers and Thunderstorms, U2, Then More Rain

Brad Leave a comment

While the temperatures may not be completely summer-like, today will be a day that indicates a clear shift towards summer weather.  An incoming disturbance will produce widespread convection today with showers and thundershowers covering much of Southern Manitoba.  Pleasant weather should make an appearance for tomorrow’s U2 concert, but Winnipeg will quickly return to rainy weather on Monday as a system that will bring significant challenges to those with housing near the lake moves into the province.

A substantial stacked low pressure system currently positioned just east of Regina is set to move across Southern Manitoba today.  A few factors will combine to produce what could be a fairly interesting afternoon today.  

First, a southerly wind, combined with yesterday’s rain has pushed dewpoints to nearly 10°C throughout the Red River Valley with a relatively deep layer of evidenced by the stratus cloud that has managed to form overnight despite winds of 15-20km/h.  This moisture will provide the fuel needed for thundershowers. 

Secondly, rather cool mid-level temperatures will be in place.  As the low pushes in, temperatures in the mid-levels should drop to -7 to -8°C, which when combined with daytime heating will produce ample instability to get convection initiating.  It is also indicative of fairly low freezing level, which will help in the generation of small hail.

And last but by far not least, the fact that this upper disturbance is stacked on top of a surface low means that there will be significant rotation through the mid and upper levels which will help storms develop rotation.

When these things combine, it’s considered a pretty classic case for cold core funnels.  These funnel clouds do not develop in the classic sense; instead of developing in the rapidly rotating updraft of supercell thunderstorms, they develop through the descent of cold air through a storm that has developed rotation due to significant mid-to-high level spin.  Think of it as a funnel cloud that develops because of how air is coming out of the cloud rather than how air is being ingested into the cloud.

These funnel clouds do have the potential to touch down and become tornadoes.  If they do, they are often extremely short lived (< 1-2 minutes) and are much weaker than the tornadoes that form from supercell thunderstorms.  Any of the storms that could produce a cold core funnel cloud are also extremely likely to be capable of producing hail.

I think that most areas across Southern Manitoba could see hail today, although the threat is biggest in the Red River Valley and east.  Winnipeg and areas south should most likely see pea-sized hail should it develop.  Further east in the Whiteshell and Sprague regions, the potential exists for marginally severe hail (about dime to quarter-sized).

The biggest hindrance to the development of all this is the lack of focus for convection.  With no strong front or trough, convection may simply blow up all over the place instead of in any organized fashion, which will leave all the storms fighting each other for resources.  If this happens, it’s likely that it would quickly blossom into a big area of showers with only the odd lightning strike.

My bet for the Red River Valley is this: low stratus this morning will burn off quickly with the morning sun.  By mid-morning, most areas should be seeing a mix of sun and cloud.  Daytime heating, combined with a weak cap, will initiate the convection earlier than typical, resulting in showers spreading into the Red River Valley around 12-1PM or shortly thereafter.  Any showers that develop in the RRV are just as likely to become thundershowers, and I think there will be numerous funnel clouds today.

As for Sunday and the big U2 concert, it should be quite a pleasant day.  We’ll see a sunny morning give way to a mix of sun and clouds in the afternoon with a daytime highs around 15-17°C.  It will cool off quick in the evening, so make sure to bring a sweater if you’re headed to the concert.


12hr. QPF valid 06Z May 31 from the 06Z May 28 GFS

After that, it looks like a significant low pressure system will track through Southern Manitoba, bringing nothing but headaches and grief for residents on the lakes.  Current indications are for a widespread area receiving 20-40mm of rain with winds potentially as high as 50 gusting to 70 km/h.  This system will do no good for the flood-striken areas near the lakes, and I would suggest that residents in the area should begin to make preparations already as with the strong winds out of the north-east, significant water damming will likely occur on the western to southern beaches.

Significant Rains for May Long Weekend

Brad Leave a comment

Balmy temperatures will be replaced by rain this long weekend as a significant low pressure system slowly pushes northwards into Southern Manitoba from the U.S. Northern Plains. Read on to find out just how much rain we can expect.

500mb Winds (12Z May 20th GEMREG valid 00Z May 23
500mm Heights & Winds from the 12Z May 20th GEMREG model run valid at 00Z May 23rd.

A powerful low pressure system continues to push northwards towards the Southern Pariries, slowly spreading rain through Southern Saskatchewan today and set to spread rain through Southern Manitoba tomorrow evening. This system is being fed by a frontal wave in the Central Plains, which is feeding moisture northwards into this low. This system is expected to continue to intensify over the next 24-36 hours, intensifying it’s rainfall production as it taps into increased instability and is fed additional heat and moisture from thunderstorms that develop and override the warm front in Nebraska and South Daktoa. Tonight, elevated thunderstorms will stream northwards through the Dakotas as they transform into larger areas of rain with embedded thunderstorms and wrap around the upper low, moving from east to west across Southern Manitoba and Saskatchewan.

This setup has the potential to produce significant amounts of rainfall. While models have been varying slightly in their position and amount of rain, they paint a fairly consistent picture:

24hr. QPF (12Z May 20 GEMREG valid 12Z May 22)
24 hour rainfall totals from the 12Z May 20th GEMREG model run valid at 12Z May 22nd.

24hr. QPF (12Z May 20 NAM valid 12Z May 22)
24 hour rainfall totals from the 12Z May 20th NAM model run valid at 12Z May 22nd.

24hr. QPF (12Z May 20 NAM valid 12Z May 22)
24 hour rainfall totals from the 12Z May 20th NAM model run valid at 12Z May 22nd.

As we can see, although the models all have varying amounts (highly dependent on how it resolves convection), they all paint a significant swath of precipitation heading our way. The GEM-REG keeps the precipitation the furthest south, and without a significant blocking ridge to the north, I’m inclined to think that it’s keeping things too far south. The current general agreement would be a swath of 0.75 to 1.5 inches of rain from Shaunovan/Swift Current through Brandon, Winnipeg and the Whiteshell.

For Southern Manitoba, we will likely see some showers or thunderstorms develop along the ND/MN border tomorrow morning and push northwards into Southern Manitoba by the early afternoon. This area of rain will slow as it approaches Winnipeg and begin to intensify into an area of rain. By late afternoon, it will likely be raining over most of Southern Manitoba and will last through most of the night. The Red River Valley will likely see a break late overnight into early Sunday morning before the rain starts again with wrap-around precipitation moving through. Winnipeg and the RRV will see approximately 20-30mm of rain if current guidance pans out, with strong east/north-easterly winds of 40km/h gusting to 60km/h.

Monday will see much cooler temperatures, with daytime highs for Winnipeg a mere 13° or 14°C under clearing skies. Next week looks cooler than this week, but we we should see plenty of sunny skies with temperatures quickly rebounding into the high teens/low twenties by the middle of the week.