Slight Chance of Showers Saturday Evening

A system tracking across the Rockies into Alberta will slide quickly across the Prairies, brining increasing cloudiness to Winnipeg and the RRV Saturday afternoon with a slight chance of showers in the evening. For more info, read on!

GEM-REG 3HR. QPF
12Z 21 October GEM-REG 3 hour precipitation accumulation valid at 00Z Sunday (Saturday Evening)

Overnight a low pressure system will track across the Central Prairies towards Manitoba with a developing N-S trough intensifying as it moves eastwards. As it enters The Pas and Norway House areas on Saturday, Winnipeg and the RRV will see increasing clouds and a strengthening southerly wind to 30-40 km/h. As the trough swings through Winnipeg in the late afternoon and early evening, we’ll see a slight chance of a shower or two. The bulk of the precipitation should stay north of the city, closer to the low, where there is more significant lift. All models bring the edge of the rain close to Winnipeg, though, so it certainly isn’t out of the question for us to end up getting 2-4 mm out of an hour or two of rain. It seems most likely, though, that late afternoon and the evening will be overcast with a scattered shower or two.

After this system passes through, we’ll enter a stagnant pattern for a couple days with daytime highs just below 10°C and overnight lows slightly below 0°C.

Ensemble 500mb Theta-E
Ensemble Mean 500mb θe

The next chance for significant weather looks to be next Tuesday night / Wednesday morning as a rather sharp 500mb cold trough swings across the province. This will present us with a slight chance of flurries overnight, but shouldn’t amount to too much. More on that next week.

Have a great weekend and enjoy these crisp fall days!

Record Setting Heat Across the Prairies

Summer has decided to hang on and not leave us quite yet, bringing record-breaking heat to much of the Canadian Prairies. A large upper ridge build into the region on Tuesday and Wednesday, pushing the jet stream all the way up to the 60th parallel which has allowed a hot, dry southwest flow to remain in place over Alberta, Saskatchewan and Manitoba for days on end. Records have fallen left in right, with some of the highest daily quantities of records being broken at once over the last two days.

How long will this heat stay with us? How hot is it going to get? Click through to read more!

On Wednesday, September 7th, 22 record highs were broken across Alberta, Saskatchewan and Manitoba:

Daily Record Temperatures set September 7, 2011

Location New
Record
Old
Record
Record
Year
Records
Began
Alberta
Cold Lake 30.4 27.8 1998 1953
Fort Chipewyan 27.0 25.0 1937 1884
Fort McMurray 31.0 28.3 1949 1944
Jasper 29.6 29.1 1998 1943
Whitecourt 29.1 26.7 1949 1943
Saskatchewan
Saskatoon 33.4 31.5 1990 1892
Collins Bay 28.0 18.8 1980 1972
Hudson Bay 30.7 30.2 1990 1943
Key Lake 30.0 21.5 2005 1977
La Ronge 29.6 27.7 1980 1923
Meadow Lake 30.2 28.5 1998 1924
Melfort 31.7 31.5 1980 1902
Nipawin 33.0 32.2 1934 1927
North Battleford 33.0 32.2 1893 1880
Rosetown 32.6 32.0 1991 1937
Stony Rapids 27.0 22.7 2005 1960
Manitoba
Fisher Branch 29.7 29.5 1980 1977
Gimli 28.3 27.9 1980 1944
Lynn Lake 29.0 23.9 1980 1952
The Pas 30.3 29.4 1934 1910
Thompson 27.6 24.5 1990 1967

Of note on this day:

  • North Battleford broke a daily record high temperature that was set in 1893, a record 118 years old.
  • Many record highs were broken by at least 2 or 3°C, and some by nearly 10°C.

On Thursday, September 8th, 22 record highs were broken across Alberta, Saskatchewan and Manitoba:

Daily Record Temperatures set September 8, 2011

Location New
Record
Old
Record
Record
Year
Records
Began
Alberta
Cold Lake 30.8 29.8 1981 1953
Coronation 32.2 31.2 1981 1928
Fort McMurray 32.1 30.4 1981 1944
High Level 27.4 26.3 1995 1967
Jasper 30.0 29.8 1998 1943
Sundre 26.9 26.0 1994 1985
Waterton Park 28.3 28.0 1994 1966
Saskatchewan
Saskatoon 34.1 33.5 1981 1892
Collins Bay 24.6 24.1 1981 1972
Hudson Bay 31.7 30.2 1990 1943
Kindersley 33.2 32.8 1981 1913
Leader 34.2 33.5 1981 1924
Nipawin 32.8 32.2 2003 1927
Stony Rapids 24.1 22.3 2003 1960
Manitoba
Fisher Branch 32.1 32.0 2003 1977
Gimli 31.1 30.0 2003 1944
Island Lake 28.1 25.2 2009 1971
Lynn Lake 26.6 23.6 1980 1952
Pinawa 30.7 30.5 2003 1964
Sprague 30.9 29.4 1932 1915
The Pas 30.3 27.5 2003 1910
Thompson 28.0 25.8 2003 1967

And today, September 9th, 2011, 18 records were broken:

Daily Record Temperatures set September 9, 2011

Location New
Record
Old
Record
Record
Year
Records
Began
Alberta
Edson 28.7 27.8 1963 1910
Fort Chipewyan 30.0 27.0 1981 1884
Fort McMurray 32.7 32.4 1981 1944
Jasper 30.4 27.2 1944 1943
Sundre 28.9 25.8 2006 1985
Waterton Park 28.5 27.4 2006 1966
Whitecourt 29.7 29.0 1981 1943
Saskatchewan
Collins Bay 28.0 23.0 2003 1972
Hudson Bay 31.7 29.0 1998 1943
La Ronge 31.0 26.6 1994 1923
Nipawin 32.1 29.2 1981 1927
Stony Rapids 29.1 22.0 2006 1960
Manitoba
Fisher Branch 31.8 31.5 1982 1977
Gimli 31.1 31.0 1982 1944
Lynn Lake 31.1 26.6 2003 1952
Sprague 31.9 30.0 1931 1915
Swan River 31.7 30.0 1998 1908
The Pas 30.7 26.8 2003 1910

This record-setting heat is all thanks to an impressive upper ridge that has built into the Prairies. This is a feature located high in the atmosphere that causes a large area of air to subside (move downwards). Combined with the fact that they build up from the south, they bring a lot of warm air along with themselves, and often result in a large area seeing sunny skies, light winds and hot, dry weather.

The upper ridge will remain in our area for the next couple days, with daytime highs remaining in the low 30°C range. Winnipeg has an honest shot at breaking our daily record high temperature tomorrow which sits at 32.4°C. Things will abruptly change next week however. On Monday a low pressure system will pass by to our north and drag a cold front down across the province. Through the following days, a large ridge of high pressure will build in from the northwest, bringing significantly cooler temperatures than the past week:

GFS Temperatures Valid 06Z Thursday 15 Sept
GFS Surface Temperatures Valid 06Z Thursday 15 September

Currently it looks like next Wednesday and Thursday will be the coldest of the days, with highs struggling to get as high as 15°C. While the last week has been a beautiful late-season blast of summer, fall is set to make an aggressive entrance early next week.

Dry Spell to Break with Showers Tonight

The stretch of dry weather Winnipeg has been experiencing over the past month should come to an end tonight as a significant low crosses across the Central Prairies.


Analysis of 20:45Z Satellite Imagery for August 7, 2011

A system that brought all sorts of severe weather to Saskatchewan yesterday evening, including a potential tornado touchdown east of Regina, is pushing into Manitoba tonight and bringing with it the chance of severe weather for Southwestern Manitoba and much-needed rain to the Northern Red River Valley.

After battering residents of Saskatchewan from the Alberta border all the way to the southeast corner of the province, the main driving force for the entire system began to slowly move eastwards last night.  As it pushes through Saskatchewan, the favourable conditions that existed through much of Saskatchewan have been pushed eastwards to eastern SK and much of southwestern Manitoba.


Watches in effect for Manitoba at 4:50PM local time.

Weather watches are out for severe thunderstorms through much of southwest and Parkland Manitoba.  Thunderstorms will continue to develop into the evening and as the low pressure system and associated trough line move into the area, many have the potential to become severe with the main threats being large hail through Minnedosa and Dauphin, and the slight chance of a tornado in addition to heavy rains and large hail through southwest Manitoba.


6hr. QPF from the 12Z Aug 7 run of the GFS model valid for 09Z Aug 8 (~4AM local)

Winnipeg and the RRV will have a slight chance of some showers this evening (with the off chance of a lightning strike or two), however the extremely dry low-levels, with dew points only around 11°C, will make it unlikely that any cells that move into our area will actually be able produce rain that makes it to the surface.  However, by 9 or 10PM tonight, the low and trough begin to enter the RRV and a large area of rain with isolated embedded thunderstorms will develop, resulting in a large north-south band of rain that will pass over the RRV tonight.  Most areas will see 5-10mm of the wet stuff with a slight chance of 15-20mm in areas that see a thunderstorm tonight.  I think that the risk for severe weather will stay in the southwest portion of the province today; overnight we should just see rain and a slight chance of a light show.

Monday will be one of the most significantly different days we’ve had over the past month.  On the back side of this low, cooler air dives down from the northern Prairies.  Much of the Southern Prairies will see highs of only 18-22°C with brisk northwest winds gusting to 50km/h, which will make it feel downright cool relative to the last couple weeks.  Here in the Red River Valley, we also have a good chance of showers moving down from the interlake into the area by the early afternoon.

After our damp, windy, cool Monday, things improve through Tuesday and we’ll be back into the high 20’s by Wednesday.  More rain may be in store for the later half of the week, but more on that later.

I, for one, welcome a nice rainy night.  So does my lawn…

Snow on the Way

A significant storm system is currently developing in Montana this morning that will push it’s way eastwards across the Northern Plains of the United States and into Northwestern Ontario by Thursday morning.

m.jpg

Snow will push into Saskatchewan today and a snow band will develop aligned somewhere between Shaunovan and Kamsack, as shown in the above model image. There is a slight chance that some of these sites will see warning-level amounts of snow, however it currently looks like the possibility of that is borderline. This band of snow will then consolidate and push into Central Manitoba, while a second impulse brings an area of lift into Southeastern Saskatchewan and Southern Manitoba.

m.jpg

This second band of snow will move eastwards through Southern Manitoba, giving most areas somewhere between 5-10cm of snow. Brisk northerly winds will push into the Red River Valley on the backside of the low as it moves into Northwestern Ontario, and with fresh snow, significant blowing snow will exist in any open areas inside the valley. Based on this projection, the snow would begin in Winnipeg late Thursday morning and last until sometime Friday morning, with the heaviest snow and worst conditions coming by late Thursday afternoon. Significant blowing snow would most likely occur during the evening and overnight period, which will be important to take into account for anybody planning to travel on Thursday evening/night, especially through the southern Red River Valley.

At least, that is how this system should evolve. The jury is still out on what will actually happen. The last 5 runs of the GEM-REG model have all produced drastically different results. The GFS and NAM offer little consensus on where the heaviest snow will be, the UKMET shows similarities to the 00Z GEM-REG run (from which I’ve gotten these images), and ensemble models show little confidence in the track and evolution of this system. Why is this? One look at the Water Vapour imagery shows the problem:

m.jpg

The two +’s in this image are the two main vorticity centers for this incoming system, and the yellow arrows depict their rough paths given the streams they are each in, respectively. This system is a somewhat unique scenario, wherein the two “streams” of air are close together, and are moving in sync. Typically, the reason this is a problem is because the models can have a hard time dealing with the energy distribution between the two streams. We have seen many times in the past where model solutions flip flop back and forth and back and forth, even when the event is close (less than 36 hours away) where the model error could be attributed to the complex dynamics that occur when this situation occurs.

So if we don’t actually know what’s going to happen, what’s going to happen?  Odds are that the RRV will get snow on Thursday.  I’ll go on record saying we’ll get at least 3-4 cm.  In a worst case scenario, a line from Pilot Mound to Winnipeg could get as much as 10-15 cm, however I think that’s quite unlikely.  If we get fresh snow in the RRV, there will be blowing snow Thursday night as the winds pick up to 50G70 km/h out of the north.  And sadly, our wonderful warm spell is going to come to an end this week, with temperatures plummeting to -20°C by Friday morning.

I’ll keep the comments of this post updated as the system develops and try to narrow down the impact it will have on Southern Manitoba.  Stay tuned!