Sunday, 14 January 2018

Top 10 Weather Events/Stories of 2017 in the Winnipeg Area

10 - Warm First Half of June with Heat Records on June 2

A prolonged period of mid-summer temperatures occurred in southern Manitoba in early June. At Winnipeg International Airport, the first half of June was tied with 1970 and 1991 as 7th warmest since 1872 with a mean temperature of 19.5°C. The warmth was at its maximum during the first week of June however. The first seven days of the month were the 4th warmest on record since 1872 and the warmest since 1988, with a mean temperature of 21.1°C, almost six degrees above normal.

The hottest day was June 2 with widespread heat records across southern Manitoba. Winnipeg International Airport reached 34.5°C, breaking the old record of 32.2°C in 1934 and 1948 for the city. Brandon reached 34.4°C, breaking its record of 32.2°C in 1948. Several other locations broke records as well. The maximum temperature recorded among ECCC and Mb Ag stations was 36.2°C in Treherne. In fact, widespread highs of 35°C and 36°C surrounded the Manitoba Escarpment from Morden to Portage la Prairie to Carberry.

In Winnipeg, the June 2 heat record was the first heat record in June since 1995.

9 - Overall Pleasant Summer but with Chilly Periods.

After a very warm start to June, the second half of June was anything but warm in southern Manitoba. The second half of June was the 6th coldest on record in Winnipeg since 1872, with a mean temperature of 14.0°C, almost four degrees below normal. This was preceded by the 7th warmest first half of June. On June 24, the maximum temperature at Winnipeg International Airport was only 12.6°C, breaking the old record low maximum of 13.9°C in 2004. It was the coldest high temperature in June since June 8, 2009 (high of 11.4°C).

Chilly conditions returned in early August as well. Daily low temperatures at the Airport averaged 9.5°C in the first half of August, tied with 1883 for 10th coldest since 1873. They were 5th coldest in the first week of August, averaging only 8.2°C. The monthly minimum temperature of 2.1°C on August 24 was the coldest in August since 2004. Some locations in southeastern Manitoba even reached close to freezing with lows of -0.1°C in Hadashville and 0.2°C in Sprague.

The summer as a whole was not far from normal. The mean temperature of 17.8°C from June to August was only 0.6°C below normal. Chilly nights are what caused the cooler average as they averaged 1.1°C below normal. High temperatures were 0.1°C above normal. The combination of seasonal days and chilly nights made the summer more comfortable for most people. The cooler mean temperature made summer 2017 the first colder than normal season since fall 2014.

In addition to the temperature patterns, the summer was very dry (explained in a later story). August was also very calm with a lack of wind. The average hourly sustained wind speed of 12 km/h made it the least windy August on record since 1953 at Winnipeg International Airport. It was also tied for second least windy month on record, being behind just July 1972 which had an average of 11 km/h.

The dry conditions contributed to the lowest mosquito numbers in decades in Winnipeg. According to Global News, the city recorded the lowest average mosquito trap counts in 30 years of record keeping. The lack of significant thunderstorms was also noteworthy, not only in Manitoba but in much of Canada. According to Claire Martin from Environment and Climate Change Canada, August 2017 had the least lightning strikes recorded in Canada in August on record since 2002. The number was a little less than 60% of average. At Winnipeg International Airport, although the number of thunderstorm days from June to August was only 2 days less than normal, the lack of precipitation was a testament of the low intensity of thunderstorm activity. Hail losses were also fewer in 2017 relative to normal across the Praries and much fewer than in 2016 according to CBC and the Canadian Crop Hail Association.

8 - Summer-Like Temperatures and Thunderstorms in Mid-October

Record warmth moved into southeastern Manitoba on October 20. Winnipeg reached 25.0°C, breaking the old record of 23.9°C in 1875 and 1958. It was the latest date to hit 25°C since Oct 23, 1963 and the 7th latest date to hit 25°C since records began in 1872. It was only a week earlier than the latest 25°C on record on October 27, 1938. Temperatures were even warmer southeast of the city with highs of 26 and 27°C. Sprague and Beausejour were the hotspots with highs of 27.2°C and 27.0°C respectively. Steinbach also reached a record high of 26.3°C. More records are listed here. The following morning was abnormally warm as well. The morning low at Winnipeg International Airport up to 8 am was just 17.6°C. This was about 8 to 10°C warmer than the normal high for the date. A cold front dropped temperatures through the day.

Up to the 22nd, October was placed at 20th warmest since 1872. However, a significant cool down in the final week dropped the monthly average. 21 days exceeded 10°C while the normal is 17 days.

Unusually intense thunderstorms pushed through Winnipeg on October 7. Intense lightning and loud thunder rumbled through the city, causing some to call it the biggest storm of the year. Another thunderstorm occurred on October 21, the 10th latest thunderstorm on record at the Airport since 1953. It brought only showers and a few rumbles of thunder.

7 - Another Year of Heat Records in September

It was mostly another warm September in southern Manitoba. In Winnipeg, it was the fifth consecutive warmer than normal September, continuing the trend of warming Septembers in the past two decades. In fact, it was the 20th warmer than normal September in the last 24 years. It averaged 14.2°C, 1.3°C above normal and tied 23rd warmest since 1872.

The heat peaked on September 12 when widespread record heat once again filled southern Manitoba. Winnipeg International Airport reached 34.8°C, breaking the old record of 33.3°C in 1952 for the date. The hottest temperatures were in west of the city where temperatures soared to 35 and 36°C. Carman and Starbuck were the hostspots at 36.0°C and 35.6°C respectively. Carman broke its old record by over five degrees (30.6°C in 1908). Using a merged dataset between ECCC and Mb Ag and locations with at least 30 years of data (not necessarily continuous), 37 of 54 locations in southern Manitoba broke a heat record on September 12.

The high of 34.8°C on September 12 at Winnipeg Airport was the hottest of the year, marking the second latest date on record since 1872 to reach the highest temperature of the year. The latest was on September 19, 2004.

6 - Cold Snap in Late December

Although the cold snap in late December was nothing unusual historically, it was unusually prolonged and cold in the current climate. The cold snap lasted from December 24 to December 31. In this 8-day period, 7 days never exceeded -20°C. Despite the cold conditions, no temperature records were broken in Winnipeg. The closest we got to a record was on December 30 when a high of -27.9°C was just shy of the record low maximum of -28.3°C in 1898 for the date.

The last week of December had a mean temperature of -27.7°C, the 4th coldest last week of December since 1872 and the coldest since 1933. This was 12.5°C colder than the 1981-2010 average for the period. Daily highs in the period averaged -23.7°C, the 2nd coldest on record for the last week of December since 1872. The coldest temperature during the cold snap was 'only' -35.5°C.

5 - An ''Early, Not So Early'' Start to Winter

After warm weather most of October, winter weather came early in late October. Much colder temperatures arrived along with snow and lake-effect snow squalls. By October 30, areas downwind of the lakes northeast and west of Winnipeg already had snow on the ground which would stay through the remainder of the winter. Also on October 30, icy conditions in the evening resulted in numerous collisions in Winnipeg. According to CBC, 97 vehicles were involved in accidents related to the icy conditions, at least 12 of which were involved in a multi-vehicle crash on the south Perimeter Highway. Bridges were temporarily closed until they could be sanded and salted. 

The daytime high on Halloween at Winnipeg International Airport was only -1.9°C, the first Halloween since 2006 to not reach the freezing mark. By November 1st, another snowfall event brought 5 to 10 cm southwest of Winnipeg. Any snow in Winnipeg had melted but snow cover was essentially circling the city. A stronger system finally brought Winnipeg a more persistent snow cover on November 4. 10 cm fell in the city, breaking the old record for the date of 8.4 cm in 1971. 

Following the snow, unseasonably cold temperatures arrived early. Winnipeg International Airport dipped below -15°C five days in a row from November 6 to 10. The cold peaked on November 9 when the cold was record breaking. The Airport dipped to -23.7°C, smashing the old record low of -20.6°C in 1933 and 1966. It was the third earliest occurrence of temperature below -23°C recorded in Winnipeg since 1872 and the earliest in over 120 years (-23.9°C on Nov 3, 1893). The high of -11.4°C on November 9 also tied with 1986 for a record low maximum for the date. The cold spot this day was Brandon Airport with a low of -26.3°C, breaking its old record -25.0°C in 1966. Just one year earlier on the same date, southern Manitoba was basking in record warmth. Winnipeg had reached a record 18.8°C on November 9th, 2016. It was truly remarkable to tie a record low maximum on the same date that a record high was broken the year before. 

On November 19, the Stony Mountain ski area had its earliest opening date on record in 50 years, beating its old record of November 22. This was also a full month earlier than the year before in 2016.  

It was believed that southern Manitoba was surely locked into winter for the long haul. However, Mother Nature had other plans, providing us a very warm finish to November and start to December. Much of the snow pack that had developed melted, resulting in mostly bare fields west and southwest of Winnipeg. Snow depth within city limits in Winnipeg dropped to only one or two centimetres with abundant grass showing up. 

4 - January 12 Classic Prairie Blizzard

The ground-blizzard of January 12 was the first official blizzard in Winnipeg since January 11, 2013. Very little snow fell with the storm - only a trace. However, just a few days before the storm, a very fluffy 10 cm of snow had fallen. This set the Red River Valley up for blizzard conditions on January 12 as a fast-moving and strong cold front brought very strong winds to the Red River Valley. At Winnipeg International Airport, winds were sustained over 50 km/h for six-consecutive hours. The peak sustained wind speed of 74 km/h at 8 am was the second strongest on record for January since 1953. The strongest was 80 km/h on January 31, 2009. The maximum wind gust during the blizzard was 85 km/h and visibility was just 200 metres for three consecutive hours. It was also one of the coldest blizzards in Winnipeg. Minimum wind chill during the blizzard was -40, 5th lowest of the 28 blizzards since 1953.

The blizzard caused significant travel delays during the morning commute and travel outside the city was next to impossible due to near zero visibility. Several drivers ended up in the ditch and there were several accidents including a 12-vehicle crash on McPhillips Street. Even within city limits, visibility was next to zero. According to CBC, flights and rural mail delivery were delayed or cancelled due to the storm. Several highways were closed, including highways 59, 75, 1, 2, 3, 23, 16, 14, 6, 8 and 9.

A blizzard in Canada is defined as four consecutive hours or more of visibility of 400 metres or less and sustained wind speed of 40 km/h or more in blowing snow.

3 - Incredible Winter Thaws and Rainfalls

Two abnormal thaws occurred in the winter, one in January and the other in February. The one from January 20 to 22 was the most extreme. Winnipeg remained above freezing for 67 consecutive hours, the longest period above freezing on record in January in Winnipeg since 1873. It beat the previous record by almost a full day! The old record being 44 hours January 8-9, 2002. For three consecutive days, Winnipeg broke a record high minimum temperature record. The low of 0.9°C on January 21 was the second highest in January on record since 1873. The following day's low of -0.1°C was the third highest in January on record. Both of the daily lows were about 23-25°C above normal! Dewpoint temperature were high as well. The maximum dewpoint of 1.9°C on January 20 was the second highest on record in January since 1953, behind only 2.4°C on January 10, 1990. Rain also fell in relative abundance on January 20. 2.9 mm fell at the Airport, the second rainiest January day on record since 1873. Even higher amounts of 4 mm fell in southern sections of the city. Small rainfall amounts also fell on January 21 and 22, bringing the monthly total to 3.5 mm. This made it the second rainiest January on record since 1873, behind only January 1944 when 3.8 mm fell.

The thaw melted the snow depth significantly with snow depths plunging 6 to 10 cm in the city. The rain also messed with power lines. Bright green flashes were reported in parts of the city during the rain on January 20 followed by power outages which lasted up to four hours.

In total, 3 temperature records and 9 dewpoint records were broken from January 19 to 28 for high maximums and high minimums. Elsewhere in southern Manitoba, McCreary reached a record 11.8°C on January 19, its 4th warmest January day on record since 1972 according to Rob. In Winnipeg, January was tied for 13th warmest since 1873 with a mean temperature of -13.1°C at the Airport.

Yet another anomalous mid-winter thaw occurred in mid February. From February 13 to 22, all but one day exceeded the freezing mark in Winnipeg. We flirted with several temperature records but never actually broke any. The high of 5.3°C on the 17th was just shy of the record of 5.4°C in 1981. Another rainfall event occurred on February 20. 1.1 mm of rain fell at the Airport, breaking the old record for the date of 0.3 mm in 1965. The same warm spell brought all-time record warmth for February in southern Ontario with highs of 18°C. Thunderstorms also occurred in northwestern Ontario and just across the North Dakota border. North Dakota received its first severe thunderstorm ever recorded in February on February 21 with 1-inch hail reported according to the NWS. It beat the previous record for earliest severe thunderstorm in the state by over a month (March 26, 2003 and 2004).

February tied 12th warmest on record since 1873 with a mean temperature of -10.0°C. Overall, winter 2016-2017 (Dec to Feb) tied with 1941-1942 for 14th warmest winter since 1872. It was the third consecutive warmer than normal winter. Also, there was a total of 200 hours above freezing from December to February, the 4th most on record since 1953 and the most since the winter of 1999-2000.

2 - Third Driest Year Since 1873

With only about 333.7 mm of precipitation (normal 527.2 mm) at Winnipeg International Airport, 2017 was approximately the third driest year on record since 1873 in Winnipeg. 286.9 mm of this was rainfall (normal 428.5 mm), the 13th least rainy year since 1873. This made 2017 the driest and least rainy year since 2006. Even snowfall was well below normal in 2017 with only 89.6 cm (normal 117.7 cm), 28th least snowy and the least snowy year since 2001.

Only April and September had above normal precipitation at Winnipeg International Airport. May, with 24.6 mm of precipitation, was the driest since 1992. The summer was also unusually dry. August was the driest with only about 14 mm of precipitation, the 7th driest August since 1873. Summer overall was the 13th driest with about 137 mm of rainfall.

The rainiest day of the year was September 22 with only 25.2 mm of rain at Winnipeg Airport. This was the 10th lowest maximum daily rainfall in a year since 1872.

Despite the dryness, it was a bumper crop overall in southern Manitoba. Perhaps rainfalls were timely enough or there was leftover soil moisture from a very wet 2016. Regardless, it was a very dry year in southern Manitoba precipitation-wise. Where issues would present themselves is if 2017 was another very dry year. One dry year is one year but two in a row can present problems.

1 - March Super-Storm - Flash Freeze, Historical Blizzard, Near-Record Low Pressure and Even Thunderstorms

A very strong low pressure system moved into southern Manitoba from south of the border on March 6. It would bring near-record pressure lows for March, a record blizzard, a record flash freeze event and even thunderstorms.

It all started midday on March 6 with thunderstorms in south-central and southwestern Manitoba. The storms dropped pea-sized hail and produced intense thunder and lightning. Locally heavy rain, freezing rain or ice pellets fell with the storms as well. Ahead of the system it was also very mild. Winnipeg Airport reached a high of 5.9°C (following a high of 6.5°C the day before).

Atmospheric pressure bottomed out at 978.7 mb (corrected to sea-level) at Winnipeg Airport at 8pm, the second lowest pressure reading ever recorded in March in Winnipeg since 1953. It was just 0.1 mb shy of the March record on March 12, 1982. As the cold front behind the centre of the low pushed through Winnipeg after 8pm, one of the greatest flash freeze events ever recorded in Winnipeg occurred. The temperature fell from 5.5°C at 8pm to -5.7°C at 9pm, an 11.2°C drop in just 1 hour! This was the second greatest 1-hr temperature drop, not related to a thunderstorm, at Winnipeg Airport since 1953. Only April 8, 1988 had a greater one-hour drop with a cold front. That date, the temperature dropped 11.9°C in one hour. The flash freeze turned everything to ice in what felt like an instant. Rainwater from earlier in the day and meltwater froze, creating significant icing on roadways.

Behind the system, a relentless blizzard pounded southwestern Manitoba and southeastern Saskatchewan all the way to Churchill in northern Manitoba. It was among one of the worst blizzards ever recorded in this swath. In Brandon, blizzard conditions went on for 31 consecutive hours on March 6 and 7, the longest blizzard on record since 1959. It beat the old record by 13 hours (18 hours on January 11-12, 1975)! 41.4 cm of snow was recorded at the Airport with blizzard. The maximum wind gust was 95 km/h and winds were at one time sustained at 71 km/h. Visibility was reported as 0 kmh for 8 hours, including 5 consecutive. The storm left drifts over two metres high in rural areas, enough to completely swallow vehicles and even buildings.

Up north, the 3-day blizzard set up one of the worst spring floods in memory as significant snowfall (30+ cm) combined with wind gusts over 100 km/h. Churchill's peak wind gust was 104 km/h. The blizzard in Churchill lasted 58 consecutive hours, the third longest blizzard since 1953. It was just 4 hours shy of the longest blizzard on record January 28-30, 1971. What was so unusual about this storm up north was the amount of snow that fell. Of the top four longest blizzard in Churchill, March 2017's was the only one that was not a ground blizzard (not without significant snowfall).

This blog post contains information, news and data originally from Global News, CBC, Environment and Climate Change Canada, Manitoba Fire and Manitoba Agriculture. Weather and climate statistics were retrieved using these data sources but where possible were quality checked by myself, the author, for correctness.

Thursday, 9 November 2017

Early Winter Now Making the Record Books

Clear skies, light wind, a frigid air mass behind yesterday's cold front and a fresh snow pack combined this morning to produce some of the coldest temperatures we have seen this early in the season in parts of southern Manitoba in at least a century.

Winnipeg Airport dropped to -23.7°C this morning, obliterating the old record of -20.6°C in 1933 and 1966 for today. It is also the 3rd earliest occurrence of temperature below -23°C since 1872. The earliest were on November 3, 1873 and 1893. This also means that this is the coldest we have been this early in the season in over 120 years in Winnipeg.

Brandon Airport was the cold spot of southern Manitoba with a low of -26.3°C at the Airport. This broke their old record of -25.0°C in 1966 and was the 3rd earliest date to dip below -26°C since 1890.

A non-exhaustive list of records are included in the following table:

New record
Old record
Record period(s)
-25.0°C (1966)
Fisher Branch
-21.0°C (1979)
-20.6°C (1933, 1966)
-18.5°C (1985)
Pilot Mound
-21.7°C (1966)
1938-1956, 1958-present
-15.6°C (1957, 1973)
Swan River
-17.8°C (1911, 1960)
At least -19.9*
-19.5°C (1979)
1956-2004, 2006-present
-15.0°C (1996)
1904, 1984-85, 1990-present
*Steinbach actual low (Mb Ag station) won’t be known until tomorrow morning. Temperature given is an 8 am temperature.

The cold spot in Manitoba was at the Leaf Rapids Manitoba Fire station in northern Manitoba with a low of about -31°C.

There is the potential for record low maximums today. Another cold night tonight across southern Manitoba with some -20°C lows possible. We moderate somewhat this weekend and we might exceed the freezing mark on a day or two early next week. It probably won't enough to melt away the snow pack. The current snow pack began November 5. If snow depth remains above 2 cm through to spring, it would be the 6th earliest starting date for the longest lasting snow pack of the winter since 1955.

Note that on this date last year, Winnipeg reached a record 18.8°C.