Saturday, March 29, 2014

March going out like a lion as major winter storm set to impact North Dakota, northern Minnesota, NW Ontario, SE Manitoba Monday

RDPS model valid Monday evening
showing large winter storm system
grazing southern Manitoba 
The never ending winter of 2013-14 is set to close out March with a bang as a major winter storm develops over the central US later this weekend, bringing heavy snow and strong winds to the Dakotas and northern Minnesota by Monday. The bulk of the heaviest snow with this storm is expected to fall mainly south and east of Manitoba, however the southern Red River Valley and SE Manitoba will likely get snow from this system along with strong winds and blowing snow. This would include Emerson, Steinbach and areas close to the Ontario border. Current indications are that Winnipeg will be on the northern edge of this large storm system, but some snow is also possible here Monday along with cold northerly winds. Note that Winnipeg will see worse conditions if the storm tracks further north, so it's important to keep updated on the progress of this storm as it develops over the next day or two.  

Blizzard watches (light green) and
winter storm watches (blue) are in
effect south of the US border
This storm has the potential to be a major snow producer over the Red River valley of North Dakota with amounts of 20-30 cm possible Sunday night into Monday night. In addition, strong northerly winds will cause extensive blowing and drifting snow with blizzard conditions likely over much of eastern North Dakota. In fact, a blizzard watch has been issued for much of eastern North and South Dakota from late Sunday through Monday night. Travellers should be prepared for poor driving conditions and possible road closures south of the border with this storm. This storm will also impact NW Ontario Monday into Tuesday as it heads east, so be prepared for poor travelling conditions if you're heading into northwest Ontario early next week.

Projected snowfall amounts (inches) from WPC/NOAA. Map shows swath of heaviest snow setting up between Grand Forks and Fargo through northern Minnesota into NW Ontario where 20-30 cm is possible Sunday night into Monday night  

Thursday, March 27, 2014

Cold end to March.. but a gradual moderating trend next week. Hopeful signs that we may be finally turning the corner in April?

March will be ending much like it began.. below normal (although not quite as cold as the the -37C we had on March 1st!) Clear skies and light winds will allow temperatures to drop to the -20C mark yet again early Friday, which would be the 15th time this month with a daily temperature of -20C or lower (normally, March only sees 5 such days in Winnipeg, and usually in the first half of the month). After a chilly start, Friday should see a nice afternoon with highs near -5C, still well below normal for this time of year, but feeling much nicer with sunny skies and light winds. The weekend looks somewhat unsettled as a weak clipper system tracks across southern Manitoba. This system will push a warm front across the area with a chance of some light snow ahead of it Saturday morning, before southerly winds bring in milder air for the afternoon as temperatures climb above the freezing mark to +2C in Winnipeg (which is actually normal for this time of year)  We may even see our first rain since early November Saturday night as a band of showers moves through the Red River valley ahead of a cold front. The mild air will be short lived however as the system advances east Sunday, with brisk northerly winds developing behind the system Sunday bringing falling temperatures. This will set the stage for a cold last day of March on Monday with temperatures some 10-15C below normal. March will likely finish with an average temperature around -12.7C in Winnipeg, about 7C below normal (normal March temperature is -5.8C based on 1981-2010 averages) and the coldest March in Winnipeg since 1996 (average temperature of -13.0C).  And according to local Winnipeg weather statistician "JJ" (from Winnipeg weather blog), this would make this the coldest December-March period in Winnipeg in 115 years (since the winter of 1898-99)  In other words, we've just been through the coldest 4 month stretch in Winnipeg in over a century!

(Check out this creative tribute to our endless winter to the "Sounds of Silence"  - Winnipeg Free Press)

But the news isn't all grim. The outlook for the rest of next week calls for a moderating trend with temperatures climbing through the week, with highs rising above the freezing mark by mid to late week. There are hopeful signs that this MAY be the start of a more significant and prolonged pattern change to milder weather as we get into mid April. But be forewarned, Aprils following very cold winters in Winnipeg are usually colder than normal.. thanks to a later than usual snowmelt. Hopefully, a milder start to April will accelerate the return of spring to southern Manitoba.  

Sunday, March 23, 2014

Frigid first weekend of "spring".. late season -30C weather over southern Manitoba as cold Marches on

The official first weekend of spring was anything but springlike over southern Manitoba as a frigid Arctic airmass brought abnormally cold temperatures to the area, averaging some 15-20C below normal for late March.  After a brisk Saturday when temperatures struggled to an afternoon high of -13C in Winnipeg (along with -25 windchills), clear skies and light winds allowed temperatures to bottom out to a frigid -28.4C at Winnipeg airport early Sunday morning. Although well below normal (average highs are now +2c, lows -8C), it was not a record low for the day (-32.2C on March 23 1974)  Temperatures this morning were even colder outside the city, with several sites recording lows below -30C, abnormally late for such temperatures even for southern MB.

Cold spots across southern Manitoba (March 23 2014)

Great Falls ........  -33.6C  (Pine Falls)
Gimli ..................  -33.4C
Fisher Branch ....  -32.2C
Wasagaming .....  -32.3C
Indian Bay...........  -32.0C (Falcon Lake) 
Pinawa ..............   -31.5C     
Victoria Beach ...   -31.0C

The cold conditions are just an extension of what southern Manitoba has been experiencing for the last 4 months now with consistently below normal temperatures. Over the past 9 weeks for example, only 9 days have been above normal in Winnipeg. The cold conditions will gradually ease over the next few days but temperatures will remain below normal much of the week before a moderating trend gets temperatures closer to normal by the weekend. So far, March is averaging around -13C in Winnipeg, well below the average March temperature of -5.8C (1981-2010 normal)  The below normal temperatures this week will ensure that March finishes as the city's 6th consecutive month below normal. 

Thursday, March 20, 2014

Spring arrives.. on the calendar only..

Projected snowfall amounts (cm)
tonight into midday Friday
Spring officially arrived at 11:57 am this morning, but it looks like Old Man Winter didn't get the memo as he gets ready to send another wintery blast across southern Manitoba tonight into Friday. A storm system over southern Saskatchewan this afternoon will track across North Dakota tonight into Minnesota Friday, spreading an area of snow across southern Manitoba tonight. Precipitation may even start as some rain or freezing rain south of the TransCanada highway to the international border this evening before changing to snow as the evening progresses. Snow will overspread southern Manitoba tonight with the bulk of the snowfall expected mainly over the southern RRV into SE MB towards the US border. (NOTE: Winter storm warnings are in effect south of the border) Snow will likely spread into Winnipeg this evening with 2 or 3 cm possible overnight. As the storm system heads east, northerly winds will increase on the backside of the system early Friday bringing much colder air from the Arctic. Strong north winds gusting to 70 or 80 km/h Friday morning will cause blowing and drifting snow in open areas, with poor traveling conditions likely outside the Perimeter, especially over the southern RRV. Things should generally improve in the afternoon and evening as winds ease off, however temperatures will be falling through the day with readings near minus 15C by evening making for icy conditions after today's melt. This latest blast of wintery weather will be the start of yet another spell of below normal temperatures across southern MB that will likely persist much of next week. This will ensure that March ends up as the 6th consecutive month below normal in Winnipeg.    

UPDATE: Actual snowfall amounts from Thursday night storm system (map courtesy of NWS Grand Forks, amounts in inches).  The storm system had a fairly narrow area of heavier snowfall mainly south of the US border into NW Ontario where 10-20 cm was reported. Snowfall amounts dropped off sharply over southern Manitoba with only 1 or 2 cm over the southern RRV. Little or no snow fell in Winnipeg.

Wednesday, March 19, 2014

Winnipeg snowfall - by the numbers

It's been a snowy winter in Winnipeg this year.  Snowfall started in mid November and has not quit, with persistent cold making the snow pile up to heights we haven't seen in a while.  Surely this has to be one of the snowiest winters on record for Winnipeg, right? Well, not really.  As of March 18th, our total snowfall this winter has been 151 cm (since October 1st)  That's well above the normal seasonal snowfall of 114 cm that usually falls in Winnipeg between October and May (based on 1981-2010 average for Winnipeg airport) And we still have a good 4-6 weeks of potential snowfall left this season to add to the total.

But as you can see from the table on the left, we still have a ways to go to even get in the top 10 snowiest winters of all time in Winnipeg, never mind the snowiest ever.  In 140 years of records, only 7 winters have cracked the 200 cm mark, with the snowy winter of 1955-56 topping the list at a whopping 252.6 cm, over twice the normal snowfall for the city. Most recently, the winter of 1996-97 has been the last winter to crack the 200 cm mark, thanks in large part to a record April blizzard of 48 cm that led to the "Flood of the Century" that spring. So although we still can get some good snowfalls between now and May, we'd have to get at least 60 cm over the next month to crack the top 5 snowiest winters in the city.

Looking at a graph of winter snowfall in Winnipeg since 1873 reveals some interesting observations. Most notable is how erratic Winnipeg snowfall is from year to year, with wild swings from well above "normal" to well below. In fact, it's tough to say what "normal" is, since snowfall varies so much every winter. One way to define "normal" is to look at a longer term average. Looking at the 30 year running average (red line), one can see that snowfall has averaged roughly 125 cm for much of Winnipeg's history since 1873. That average started to dip in the 1970s and 1980s with several below normal snow seasons during that time. As a result, our 30 year running average dipped to a low of 110 cm by the 1990s. Since then, average snowfall has been trending up again, with a trend towards that 125 cm average thanks to the last few winters. Perhaps this is nature's way of reverting back to more typical snowfall amounts for this part of the world.
Graph of winter season snowfall in Winnipeg since 1873
Red line shows 30 year running average (cm)
The graph also shows another interesting tidbit. The least snowy winter in Winnipeg was way back in 1877-78, during Winnipeg's warmest winter on record. Only 31 cm of snow fell that entire winter, during the "year without a winter" that was a result of an unusually strong El Nino that year that had worldwide impacts on weather, rainfall and crops. December 1877 was virtually snowfree in Winnipeg (only 0.5 cm the whole month) and no month that entire winter exceeded 8 cm of total snowfall. Incredible.  (*NOTE: Some recent information suggests that Winnipeg may have experienced a significant snowfall later that spring on May 2 1878. In a Department of Transport study on the "Climate of Winnipeg" (Labelle, Brown, and Hasinoff, June 7 1966), it notes that the heaviest May snowfall on record in Winnipeg was 10.7 inches (27.2 cm) on May 2 1878. Officially in the digitized climate archives online, snowfall for Winnipeg on that date is listed as only 1.8 cm, or 0.7 inches. It's possible the data was incorrectly entered into the climate database as 0.7" instead of 10.7". Note that the nearby St Andrews climate site recorded 12" of snow (30 cm) on May 2-3rd 1878, so the potential is there that Winnipeg had much heavier snow that day than the current archive shows. I will update this info if and when I hear more.)       

One last but important note. Snowfall observations are no longer taken at Winnipeg airport which was the official source for snowfall observations in the city since 1938. (St John's College took snowfall observations in Winnipeg between 1873-1938)  Due to automation and a change in observing responsibilities, snowfall records at the airport stopped in 2007. Since then, snowfall readings for Winnipeg have been based on snowfall observations taken from my Charleswood observing station, an official climate station with Environment Canada. I take two snowfall readings a day from October to May, including snow depth, and send the reports to Environment Canada who archive them in their climate database. Snowfall readings at my site will not always be representative of snowfall at the airport, but at least we have some record of snowfall for the city, in the absence of official snowfall data from Winnipeg airport. 

Monday, March 17, 2014

Seasonable weather this week.. turning colder again by the weekend..

It was a pleasant start to the work week in Winnipeg after Sunday's short but intense snowstorm brought up to 10 cm of snow to the city last evening, along with whiteout conditions due to strong southerly winds gusting to 75 km/h. The next few days will see generally benign weather over southern Manitoba as weak ridging crosses the province, while a stronger storm system over the Dakotas brings wintery weather south of the border over the next day or two. Temperatures will be seasonal with afternoon high temperatures near the freezing mark through Thursday. By Friday however, an Arctic ridge of high pressure from the Northwest Territories  is forecast to push south into the Prairies, bringing another spell of below normal temperatures through the weekend into next week. So although spring officially begins this Thursday March 20th at 11:57 am, it doesn't appear that Mother Nature is eager to usher in prolonged springlike conditions anytime soon over southern Manitoba. But that shouldn't be a surprise. Of the top 15 coldest winters in Winnipeg since 1872, NONE were followed by a warmer than normal March. And it looks like Mother Nature is keeping to the script.  

Saturday, March 08, 2014

FINALLY! A taste of spring on the way!

Water jugs being delivered to Winnipeg homes
affected by frozen water lines.  The long cold winter
has resulted in an unprecedented number of homes
being affected. (CBC news image)
After a record breaking cold start to the month, some warmer weather is finally spreading into southern Manitoba this week, as a milder Pacific flow of air brings above seasonal temperatures across the Prairies. For southern MB this will mean temperatures climbing to and even above the freezing mark much of the week, the first prolonged spell of above normal temperatures here since mid January, and the first spell of above freezing temperatures since November.  This will be welcome news to frozen Winnipeggers who are coming off the coldest winter in 35 years that has plagued the city with a growing crisis of frozen water pipes and bursting water mains across the city.  The prolonged severe winter has resulted in a much deeper ground frost than normal (up to 3 metres deep in places!) which is playing havoc with water lines, with news today that up to 5000 properties in the city may be impacted by frozen water lines.  The mild weather this week, although favourable, will do little to ease the situation in the short term, as it will take several weeks for the ground to thaw given the frost depth and deep snowpack.

But the mild weather this week will be a welcome sign that spring weather is finally arriving in southern MB, something residents here didn't think would ever happen this year, even as recently as a week ago. Temperatures in Winnipeg will be climbing to the +2 or +3C mark Sunday and an even warmer +4C for Monday as we get a westerly flow of mild air from Western Canada, where temperatures reached the low teens in southern Alberta today including +12C in Calgary.  Temperatures will cool off slightly Tuesday and Wednesday before another surge of above freezing temperatures moves in for Thursday. Slightly colder weather is excepted for the weekend into next week with temperatures near or slightly below seasonal values which are now around -3C for daytime highs, and -13C for lows. All in all, a nice stretch of weather coming up this week for winter weary Winnipeggers.  Enjoy it.. we deserve it!          

Tuesday, March 04, 2014

Cold wave easing.. milder but unsettled conditions on the way

The frigid weather pattern of the past week will finally be easing this week as an unseasonably cold Arctic airmass lifts out of the Prairies. In its place will be a milder but unsettled weather pattern developing, as weather systems from the Pacific push across the southern Prairies.  The first such system is expected to spread snow into southern MB by midday Wednesday, with 2 to 4 cm possible by Wednesday evening along with increasing southerly winds gusting to 60 or 70 km/h which will likely produce some blowing and drifting snow.  Periods of snow will continue Wednesday night into Thursday with another 5 to 10 cm possible as the main storm system tracks east of Manitoba, but temperatures will finally be rising to seasonal values near -4C.. a virtual heat wave compared to the Arctic conditions that began March. Some briefly colder weather will follow in the wake of this system for Friday and Saturday, before another storm system brings in milder but snowy conditions for next Monday or Tuesday.  Yes, more snow in the forecast, but at least, a little more seasonable weather to look forward to in the days ahead..

Saturday, March 01, 2014

Frigid start to March

Early morning lows across southern MB -  March 1 2014
Winnipeg came within 0.8C of record low for Mar 1 (-37.8C Mar 1 1962)
Note sub -40C readings in Wasagaming and Carberry

(map courtesy of @jjcwpg)
It was a frigid start to March over southern MB as a massive outbreak of Arctic air swept across the Prairies overnight.  Temperatures early this morning bottomed out in the -35 to -40C range over much of southern MB, with the coldest reading of -42.8C at Wasagaming in Riding Mountain National Park.  In Winnipeg, the temperature fell to a low of -37.0C, over 20C below normal for March 1st (normal low of -15C)  The reading came within 0.8C of the record low for the day, which was set during a similar Arctic outbreak in 1962 when Winnipeg hit a record low of -37.8C on March 1st.  (That 1962 Arctic outbreak was even colder than this year's, with temperatures bottoming out at -41.7C in Brandon, and -45.6C in Sprague!)

Wind chills got down as low as -50 in Winnipeg
around 7 am on March 1 2014 setting a
new record low wind chill for March
The cold temperatures this morning were made even worse by winds of 15-20 km/h that produced dangerous wind chills down to -50 in Winnipeg around 7 am (-36C with a 18 km/h wind).  That set a new all time record low wind chill for March in Winnipeg, beating the previous low of -49 set on March 1 1962. (Note: Wind chill records only go back to 1953 in Winnipeg. They were not calculated before then) The cold conditions continued through the day with an afternoon high of only -26.0C, over 20C below normal for the day (normal high of -5C)  That was cold enough to set a new record low maximum for the day in Winnipeg (previously -22.2C on March 1st 1972) and was also the 2nd coldest maximum daily temperature ever in March (second only to a high of -26.7C set on March 7 1880)

In addition, the average temperature of -31.5C for the day made it the second coldest March day on record in Winnipeg since 1872, behind the -32.0C daily average of March 7 1880 (max -26.7C, min -37.2C)   Note that the daily average of -31.5C was about 21C below normal for the day (normal for March 1st is about -10.5C)  Daily anomalies of 20C are very rare, and indicate extreme out of season type weather. The last time Winnipeg had a daily anomaly of more than 20C was on March 19 2012 when we posted our warmest March day ever at 23.7C (with a low of 13.3C) That day was 23C ABOVE normal. In other words, yesterday's cold for this time of year was as unusual as the warmth was in 2012! An interesting statistic that really highlights the extreme volatility we've seen in the weather these past couple of years.

The unseasonably cold weather will continue for the next few days, but a moderating trend is expected by the end of next week as temperatures climb closer towards normal for early March.