Big change in the weather pattern Friday into the weekend.. strong winds, colder temperatures and possible snow..

Wind and wave impact maps for south basins
of Lakes Winnipeg (right) and Manitoba (left)
Severe impacts are possible Friday Oct 3rd
along south shorelines (in red)
(image from province of Manitoba)

It was a pleasant Thursday over the Red River valley with mainly sunny skies and afternoon temperatures up to 19C. But a major change in the weather is arriving tonight in the form of a strong cold front that is pushing across western MB late this afternoon. Showers and even some isolated thunderstorms will accompany this front this evening, followed by a northwest flow of much cooler air tonight into Friday. Friday will be a much colder day, with temperatures some 10-13C colder than today along with occasional rain or drizzle and strong northwest winds gusting to 70 km/h. The rain may even mix with some wet snow over higher elevations of the western RRV Friday. Northwest winds will be especially strong over Lake Manitoba and Lake Winnipeg overnight into Friday morning with gusts to 80 km/h at times. The province of Manitoba has a issued a severe wind alert for Lake Winnipeg and Lake Manitoba warning that strong northerly winds and significant wave action may cause lake levels to rise up to 5 feet over the south basins. Note that lake levels are higher than normal due to excessive summer rainfall, especially over western MB. Lake Manitoba is at 814.2 feet while Lake Winnipeg is at 715.6 feet above sea level. The higher than normal lake levels together with strong wave and lake seiche action will lead to shoreline erosion concerns particularly along the southern and eastern shores of the lakes.

Video:  See video footage of waves at Twin Lakes on southeast shore of Lake Manitoba Friday. (from CBC)

Snowy scene Friday afternoon near Lake Brereton, MB
in the Whiteshell Park area, just one week
after experiencing 30C temperatures 

As the main precipitation shield from this system pulls away Friday, narrow bands of lake effect showers will develop over and to the south-southeast of the MB lakes. In fact, it's possible these lake effect showers may change over to snow inland from the lakes as temperatures drop Friday night into early Saturday, with the potential for accumulating snow in some narrow bands southeast of the lakes. Cold and blustery conditions will persist through the weekend with temperatures some 5-10C below normal for early October.

Record blast of late season heat over southwest Manitoba

4 pm temperatures across RRV and SW MB - Sep 25 2014
Temperatures soared into the 30s over SW MB

A sprawling upper ridge of high pressure over central North America together with a southerly flow of unseasonably warm air from the southwestern United States resulted in a late season blast of summer like temperatures over southern MB today, especially over southwestern parts of the province. Temperatures soared into the upper 20s over the Red River valley, and into the low to mid 30s over southwest Manitoba. These temperatures were some 13 to 18C above normal for late September, and resulted in some impressive late season heat records. In Brandon for example, the high of 34.0C at YBR airport was not only a record for the day (prev record 31.1C in 1950), but was also the latest the city has hit a temperature over 33C (previous latest was on Sept 22 1938 with a high of 33.9C)   It was even warmer southeast of Brandon with a high of 35C in Wawanesa from the Manitoba Ag weather network.  South of the border, WiIlliston ND hit an incredible 36.1C (97F), easily a record for the day and the latest the city has ever been that hot.

Record highs across the central Prairies Sep 25 2014
(Graphic from The Weather Network)

In Winnipeg, temperatures weren't quite as high as areas further west, but it did manage to reach a high of 27.7C at Winnipeg airport.. the warmest day of the month so far and about 13C above normal. The day was accompanied by brisk southerly winds and abnormally high dewpoints for late September.. with a dewpoint reading of 18C by the afternoon and evening. This was the highest dewpoint ever recorded for Sept 25th and is one of the latest days in the year for dewpoints of 18C or more (latest is Oct 11 1997 with a dewpoint of 18.1C)

Friday should be a repeat day over southern MB, with temperatures in the upper 20s and low 30s once again along with sunny skies and humid conditions (dewpoints again in the upper teens) Southerly winds however will be stronger Friday in Winnipeg and up the RRV, with gusts to 60 km/h or more. Temperatures should climb to a high of 28-29C in Winnipeg, just shy of the record high for Sept 26th of 31.7C set in 1952. Saturday will see one more warm day over the Red River valley with highs in the mid 20s, before a cold front pushes through by afternoon.  This front will usher in much cooler air by Sunday with highs only in the low teens along with periods of rain. So enjoy these last couple of summer like days before reality kicks back in!

UPDATE: Fri Sept 26:  It was another unseasonably warm day across southern Manitoba with temperatures climbing to the 30C mark or higher in most areas.  Winnipeg hit a high of 30.2C, some 15C above normal for Sep 26th, and just 1.5C shy of the record high for the day. In addition, humidity values were unusually high for late September with dewpoints of 18C through midday, resulting in a peak humidex reading of 36C by late afternoon, the latest in the season that Winnipeg has hit a 35C+ humidex since humidex records began in 1953 (previous latest on record was a 38C humidex on Sep 19 2004). The hot spot in the province and country today was Swan River at a sizzling 35.1C.

Fabulous first week of fall ahead!

Great harvesting weather is expected this week
across southern MB with dry and warm conditions
(photo by Shawn Dziuk near Glen Ullin, ND) 

After a gloomy and occasionally damp weekend, the weather pattern will be turning decidedly warmer and drier across southern Manitoba this week as an upper ridge of high pressure builds across the Prairies. The result will be a fabulous stretch of dry and warmer than normal weather over the upcoming week with temperatures climbing into the mid 20s at times, and possibly even upper 20s by late week. This will be welcome news for farmers trying to harvest this year's crop, and just in general for any outdoor activities. Fall officially arrives Monday evening (Sept 22nd), but fall-like weather will be delayed for awhile as we get a nice last taste of summer-like weather this week. Officially, Winnipeg has yet to record its freeze of the season yet, with a minimum temperature so far this month of +1.1C at YWG airport (Sept 12th) On average, Winnipeg usually records its first freeze of the season by Sept 22nd, so the growing season will be extended a bit longer than normal this year. After this past winter's bitter cold and slow start to spring, we deserve it! Enjoy!

Warming trend this week

After an early taste of fall like weather, temperatures will be returning to more normal values this week over southern Manitoba as a large cool airmass pushes east out of the Prairies. In its place, a moderating trend will become established over much of the Prairies as a zonal upper flow develops, allowing milder air from western Canada to spread east across the Prairies into southern Manitoba. This will allow temperatures to climb into the upper teens over the next few days and lower 20s later this week, which is near or even a bit above normal for this time of year (normal high for Winnipeg is now 18C)  High temperatures Wednesday may dip into the mid teens as we get sideswiped by a cold front pushing through the Interlake into NW Ontario, but then temperatures should rebound quickly for late week into the weekend and next week.  In addition, the weather should remain generally dry this week over southern Manitoba until Friday when a system will bring the next main threat of showers. The upcoming warmer and drier weather pattern will be most welcome by farmers looking to ramp up harvesting activities after an unsettled first week and cool second week of September.  

Enjoy the summerlike weekend.. an early blast of fall coming by Tuesday

Say goodbye to summer this week!
850 mb temperature map shows blast of cold air
flooding across the Prairies by late Monday

It was a lovely Saturday over southern Manitoba as afternoon sunshine and southwest winds pushed temperatures well into the 20s across the RRV, including a high of 25.3C in Winnipeg, about 5C above normal for this time of year. Sunday looks just as nice with sunshine and light southerly breezes pushing afternoon temperatures back to the 25C mark again.. perfect weather to enjoy the Broadway ManyFest street festival, the annual Bombers-Riders Banjo Bowl game, or any other late summer outdoor activities. Enjoy it while you can because there are BIG changes coming in the weather this week across the Prairies. An unseasonably cold airmass will be barreling down from the Arctic early this week, bringing a blast of well below normal temperatures from Alberta to Manitoba. This colder airmass will be ushered in by a cold front pushing across southern Manitoba late Monday into Monday evening. Temperatures in the 20s Monday afternoon will plummet Monday night, with temperatures on Tuesday struggling in the 10-13C range along with cloudy skies and brisk north winds, making it feel more like October than September. The cold weather will persist the rest of the week with cloudy skies, patchy light rain or drizzle, and temperatures only in the single digits to around 10C.  That's a good 10C below normal for this time of year.  If that wasn't bad enough, higher elevations of western MB (such as the Riding and Duck Mtns, Turtle Mtn, etc) may even see the season's first flakes of .. *gasp*.. SNOW by mid week! (Very early, but not unprecedented for those higher elevations) The saving grace is that clouds and wind may prevent a widespread killing frost during the week for the remainder of southern Manitoba, but if there are any areas that clear at night, frost will be a major concern during mid to late week. So enjoy the summerlike Sunday.. a taste (or more like a heaping serving) of fall is on the way!