Tag: Rain

Chance of Showers in Winnipeg Tuesday Evening

Brad Leave a comment

A developing low pressure system in Montana is set to move eastwards overnight bringing rain and thunderstorms to much of Saskatchewan and Western Manitoba.  Complex dynamics come into play as it moves into the Red River Valley, resulting in some uncertainty to exactly what Winnipeg and the Red River Valley will see come tomorrow evening.

A large area of rain and thunderstorms will develop north of a low pressure system tracking across the Northern Plains of the United States stretching northward to a parent low pressure system anchored to a strong upper feature moving across Central Alberta into Central Saskatchewan.  This area of precipitation will track into Southwestern Manitoba by Tuesday morning.


12Z 26 July GEMREG 12-hr QPF valid 12Z 27 July

By tomorrow morning, these two discrete but connected systems will begin to change paths.  The low moving across the Northern Plains will continue to move due east, skirting along the International Border as it moves towards the Great Lakes.  The low moving into Saskatchewan will become captured by the upper feature and will quickly halt it’s eastward progression and slowly move northwards near the AB/SK border.  Connecting these two features is a large trough line that will disconnect from the US low and swing northwards into the Interlake region of Manitoba.


12Z 26 July GEMREG 12-hr QPF valid 00Z 27 July

The above image shows the total precipitation by 00Z Tuesday evening.  The disconnect of the two features is somewhat evident on this image; the bullseye of higher precipitation amounts on the AB/SK border is the enhanced precipitation associated with the slow-moving captured low pressure system.  The nose of precipitation pushing into Northern Minnesota with the arm extending south through the Dakotas is associated with the quicker-moving US low.  And lastly, the higher amounts through the Dauphin/Minnedosa regions is due to the trough line rotating northwards.

The challenge in this situation is how much precipitation will move through the Red River Valley.  As these features move apart, the lift that generates precipitation will dramatically weaken, and we could see a wall of rain to our west quickly fall apart before it reaches Winnipeg or the Eastern RRV.  If we’re able to get some sunshine, we may get enough heating to help produce convection to enhance the rainfall as it moves our way.  Lastly, slight variations in the track of either low could also dramatically alter where the precipitation falls.

Unfortunately, for an area on pace to set a record for it’s driest July on record, it isn’t inconceivable that a solid line of rain entering the Red River Valley won’t quickly split, and have part of the rain head northeast into the interlake and another part skirt along the International Border, leaving Winnipeg and many other areas in the RRV cloudy with nary a drop of rain.

It’s a difficult situation to forecast, and ultimately, it’s too early to have any certainty with where these systems will track as none of them actually exist quite yet.  One thing for certain: this is the kind of system that we’ll be able to forecast what will happen quite a bit better by tomorrow morning!  If the rain does move through the whole RRV, we may see a much-needed 5-10mm of rain, with a slight chance of local amounts near an inch if some embedded thunderstorms are able to get going.

That’s what I’m hoping for.  Although the water table remains quite high in Southern Manitoba, surface soil moisture is now extremely low.  This, coupled with  the late start to the growing season, has resulted in significant stress on crops that haven’t had the time to develop deeper roots yet.  For many farmers in S. MB, a half-inch or inch of rain would be quite welcome!

Rain Returns to the Red River Valley

Brad Leave a comment

While July has been a wonderful summer month (perhaps a little too wonderful at times), my lawn and my wallet are both ready for some cooler weather and some rain.  The cooler weather certainly has arrived; was anyone outside yesterday?  Even with the wind it was wonderful!  And, fortunately for my tomato plants, it looks like some rain is on the way as well.  Read on to find out the details!


16:15Z Daytime Multispectral Composite Satellite Image

The upper ridge that brought near-record Humidex values to Southern Manitoba earlier this week has finally moved off towards the east, which has allowed the upper trough situated along the B.C. Coast to begin moving inland.  As it migrates eastwards, it will spawn two low pressure centres: one over Central AB and a second one that will move through Montana and along the North Dakota/South Dakota border.  This will result in a rather complicated setup come Saturday morning with a surface low pressure system anchored to the upper low over Central AB with a secondary surface low pressure system anchored to a shortwave rounding the upper trough across the ND/SD border, with an elongated surface trough connecting the two.


GEM-REG Fri. July 22 12Z Model Run valid Sat. July 23 @ 12Z; 3hr. QPF + MSLP

In short, this setup will bring with it two bouts of precipitation.  The first will arrive through the morning hours on Saturday.  It’s exact placement is still quite certain, as it will be produced by nocturnal convection along a 30kt southeasterly low-level jet.  As the evening progresses today, it will become quite a bit clearer as to where exactly the thunderstorms will track.  That being said, it’s quite likely that areas near the international border will see 10-15mm of rain tomorrow morning with a few embedded thunderstorms as this system passes by.  Currently, it looks as if it’s up in the air as to whether or not it will reach as far north as Winnipeg, however I suspect we’ll see a sprinkle or two tomorrow morning.  I certainly won’t dismiss the possibility of a good shower or thunderstorm here tomorrow morning with local amounts around an inch, though!

After that, the upper trough will begin to swing in during the afternoon, and that will bring with it a band of rain that will track through in the late afternoon and evening, bringing an additional 10-15mm to what has fallen already.


Total Accumulated Precip. from the 12Z GEMREG Fri. July 22 valid 12Z Sun. July 24 (Sunday Morning)

All in all, most of the RRV should see 0.75-1.25 inches of precipitation tomorrow distributed between two distinct rain events: relatively early in the morning and late in the afternoon.  Cloudy skies will likely dominate between the two events, limiting our daytime high to only about 20°C.

After this system clears out tomorrow evening, we should have a few nice sunny days with highs in the mid-twenties.  The next chance for rain looks like Tuesday evening, when a weak system moving through brings the slight chance of some late-day showers or thunderstorms.

Rain and Thunderstorms for Next Week

Brad Leave a comment

The soggy spring we’re experiencing in Southern Manitoba just doesn’t seem to be letting up.  With some areas in Southeast Saskatchewan and Southwestern Manitoba already having seen in excess of 2/3s of what they normally receive through an entire year, everybody, including the ground, is ready for a break from the rain.  Unfortunately, it doesn’t look like it’s in the cards.  A sunny and warm weekend will change into quite an unsettled pattern for the first half of next week.  Read on to find out where and how much rain will fall.


24hr. QPF valid 12Z Monday morning from the 00Z Friday Jun 10 GEMGLB model.

Enjoy the sunshine and warmth today and tomorrow!  Plenty of sunshine is in store for us with daytime highs in the low twenties and fairly light winds.  Most of Sunday will be pleasant as well, but by evening a new system is going to be pushing into Southwest Manitoba.

An trowal will swing through Southern Manitoba Sunday night through Monday, bringing with it another batch of rain and thunderstorms.  By Sunday evening, rain will begin to push into Southwest Manitoba with a chance of thunderstorms developing before midnight.  While much concern exists about the more rainfall for SW Manitoba, it looks currently like the greatest threat for heavy rain exists from areas south of Winnipeg and spreading eastward through the Whiteshell.

As the trowal rotates into our area on Sunday, an area of thunderstorms should rapidly develop on Sunday evening in North Dakota near and east of the triple point of the associated wave.  For those who don’t know what that is, the triple point is the point where the warm front and the cold front meet.  This should develop upscale quite rapidly into a large MCS that will track east northeast and should cross into S. MB overnight.  Currently, it appears that Winnipeg would be on the northern edge of the higher amounts, with it likely that areas south of the city could see 20-40mm of rain.  Areas elsewhere in Southern Manitoba (including the Southwest corner) that are not impacted by the MCS from North Dakota will see between 10 and 20mm of rain through Monday evening.

This system will then pull northward and rotate into Central Manitoba.  Unfortunately, this prolonged period of rain could bring an additional 20-30mm to the absolutely soaked Interlake region, which is battling un-before-seen high lake levels.

Perhaps of even bigger concern is the next system that will barrel into Southern Manitoba on Wednesday evening.  While details are sure to change, this has the potential to be the most significant convective system we’ve experienced this year.  An extremely intense shortwave will head northeast into North Dakota through the day on Wednesday and initiate a large area of convection by Wednesday evening.  This convection will be pulled northward with the shortwave as it slowly becomes captured in an upper low and rests over the western lakes.  


12hr QPF valid 12Z Wednesday morning, June 15 from the 00Z Friday June 10 GEMGLB.

Thunderstorms will develop and intensify through an upper trough and pull northward into the upper low, resulting in prolonged, intense precipitation along a fairly narrow band.  Positioning will be crucial for this system, but with the potential to be dumping 1.5” – 3” of rain through the RRV into the Interlake, this will be a extremely important system to keep an eye on.

So get out and enjoy the sun!  As summer tries to push in next week, the storm track is going to move back into Southern Manitoba and we are likely going to see several impulses move through during the week.

Significant Storm System Heading into Manitoba

Brad Leave a comment

A powerful early-summer storm system has pushed through Montana overnight and pushed into Southwestern Manitoba, bringing with it heavy rain and widespread thunderstorms.  Read on to find out what’s in store for today, and where there might be severe thunderstorms…


0845Z 10.7u/3.9u Multispectral Satellite Imagery; a extremely large area of thunderstorms covers most of Southern Saskatchewan, the northern half of Montana.  This system also has an arm of convection that extends west-east across northern North Dakota approaching the international border.  This system has brought nickel sized hail to the Estevan region and 90km/h wind gusts to northern Montana.

A significant storm system ejecting from the Rocky Mountains intensified rapidly overnight and has produced widespread thunderstorms throughout southern Saskatchewan.  This system will move eastwards through the day today, pushing precipitation through Manitoba.

The setup today is quite complex.  There is a surface low running near the international border that is connected to the upper-level impulse.  These two features are acting in tandem to produce much of the convection in Saskatchewan this morning.  Further to the southeast, a surface low is entering into western North Dakota with an associated frontal wave attached to it.  A warm front extends through southern North Dakota and across central Minnesota, with a cold front laying south from the low pressure centre along the Montana/Wyoming – Dakotas boundaries.


1000Z Radar Composite for the Prairies

So!  For Southern Manitoba today.  The band of thunderstorms stretching from Melita-Virden to Emerson should continue through the early morning hours, but will be sheared apart by mid-to-late morning as the western portion of the line is pulled westward around the upper low and the eastern half is pushed further east by a significant low-level jet.  I think that there will be thunderstorms up to a line that lay from Portage la Prairie – Winnipeg – Kenora.  North of that line (including Portage and Winnipeg), I’d say that there’s a good chance of some showers this morning, but only a slight risk of a thunderstorm as the line is weakened through the stretching as well as the morning sun.

After that line passes, we’ll see a relatively cloudy lunch and early afternoon.  During this period, the warm front in North Dakota will have advected northward and lay fairly close to the Canadian border.  By mid-afternoon, convection will initiate south of the border along the warm front, caused by daytime heating and increasing instability as the upper centre approaches.  These storms will probably become marginally severe to severe quite quickly, with the main threat being large hail.  There is a slight chance that storms right near the warm front could produce tornadoes.

I think that the worst should stay south of the border, but it’s highly dependant on how far north the warm front can push.  The SPC agrees with me, and has pushed their slight risk area into Southern Manitoba, with concerns that the worst could actually occur on our side of the border.  I’d advise anyone living within 75km of the border in the Red River Valley and east to keep an eye out for weather watches or warnings this afternoon.


24hr. precipitation accumulation valid 12Z Wednesday morning from the 00Z June 7 GEMREG model.

Storms that initiate along the warm front should become elevated this evening, as they become support by a strong low level jet overrunning the warm front.  As the upper low moves across Southern Manitoba, it too should support an area of convection due to significant instability aloft.  All this will move through overnight, giving rain and thunderstorms to many areas in Southern Manitoba.  Rainfall amounts may vary significantly depending on convection, but general widespread amounts will likely be from 15-25mm, with areas that get battered by thunderstorms potentially seeing 30-40mm.

We should see some light rain tomorrow morning through the RRV and points east as the system pulls out, with skies beginning to clear through the afternoon.  After that, it looks like we’ll have at least a few days without rain before the next system moves through!