Catching up on Seasonal Summaries - Spring 2015

After two consecutive cold springs, 2015 finally brought some warmer conditions. Spring 2015 averaged 4.5⁰C, tying with three other years for 22^nd warmest spring since 1873. This was a nice change after a 16^th coldest spring in 2013 and 18^th coldest spring in 2014.

Early Spring

Nearly-snowless Winnipeg on March 13

Similarly to 2010 and 2012, spring came very early in southern Manitoba this year. The winter snow pack disappeared already by mid March, allowing for temperatures to reach well into the teens, at least 15 degrees above normal for that time of year. The peak of the warm spell only lasted a couple days on March 14 and 15 but was still pretty impressive. Temperatures were highest along the US border. Morden reached highs of 18.3⁰C and 17.6⁰C, the earliest readings over 16⁰C on record since 1904. The 18.3⁰C high on March 14 also broke the old 2012 record by an impressive 7.1 degrees! Winnipeg also broke a record on March 14 with a high of 13.2⁰C (old 11.4⁰C in 1981). A high of 14.3⁰C the following day was just shy of the old record of 14.4⁰C in 2012. Nights were unusually mild as well. A morning low of 6.7⁰C on March 15 was the warmest morning low for so early in the year since 1953. The last time we had a morning low that warm and that early in the season was on March 19, 2012 with a morning low of 16.0⁰C.

Snow cover in Winnipeg disappeared by March 15, tying with 1995 for 3^rd earliest snow melt since 1955. This occurred over a month earlier than in 2013 (April 28) and 2014 (April 21) and was similar to a 2^nd earliest snow melt in 2012 (March 14).

In the end, March averaged -3.0⁰C in Winnipeg, the 20^th warmest March since 1872.

The first thunderstorms of the season occurred on March 30 with some lightning and pea-sized hail north and south of Winnipeg.

Mild and Dusty April

Blowing dust on Kenaston, Blvd April 15 (by ChrisD.ca)

There were a couple brief but significant cool downs in early and mid April. However, a generally warm pattern continued. The first 20⁰C of the year occurred April 11 with a high of 22.1⁰C, just over a week earlier than normal. 

An early spring combined with limited winter and spring precipitation to create dry soils in April. Dust was blown around on warm and windy days as a result. April 15 was the worst when southerly wind gusts over 80 km/h caused locally reduced visibility in blowing dust. Smoke from brushfires only worsened visibility and breathing conditions. The winds also caused some property damage, such as to windows and shingles, according to social media reports. The strong southerly winds were also transporting some record breaking warmth. Winnipeg’s high of 24.8⁰C broke the old record of 24.1⁰C in 2006.

Another hot spell occurred late April with highs reaching high 20’s. A high of 27.4⁰C April 30^th in Winnipeg was the warmest in April since 2001.

Wetter in May

Conditions turned wetter come May across southern Manitoba with above normal rainfall. Winnipeg missed the worst with the bulk of the rain occurring to our south, especially south of the border. In fact, Fargo, ND recorded its wettest May on record with close to 200 mm of rain. 

May Long Weekend Colorado Low

Snow & uprooted tree in Wpg Beach (by @seanledwich)

One of the most intense low pressure systems in the last decade occurred just in time for the May Long Weekend. Rain, wind and even snow were problems for 2-3 days. Sunday, May 17 was downright miserable with sustained winds of 50-70 km/h, wind gusts up to 90 km/h, temperatures in the low to mid single digits and all-day steady rains. Winnipeg Int’l A recorded 31.3 mm of rain for the day, breaking the old record of 22.9 mm in 1903. The 2-day rain total was generally 35-55 mm in Winnipeg and 50-90 mm along the US border. Overland flooding, especially over farm fields, occurred. The strong and damaging winds also lasted for several hours, causing minor damage and ripping twigs and branches off trees.

 

Rain changed to snow Sunday night into early Victoria Day morning (May 18). 2.5 cm fell in Charleswood in Winnipeg, the latest occurrence of snow since 2002 when a trace cm fell on May 23. This was also just shy of the old record of 3.0 cm in 1963 for the day. Prior to this year, snow had fallen on May 18 only four times since 1872. Even heavier snowfall fell west and north of the city with 10-15 cm from Boissevain to Lake Manitoba to the western shore of Lake Winnipeg.

A full summary of the system was provided by A Weather Moment.

The Year up to Now

The year up to May averaged almost bang on normal with an average temperature of -3.9⁰C. Only February finished well below normal at 5.7⁰C below normal. January and March were almost 3⁰C above normal.

Wet and Humid August

Temperature-wise, August 2015 was pretty much bang on normal with an average mean of 18.5°C. Hot and humid conditions occurred mid and late month with a few cooler periods in between. Overall, rainfall and humidity levels were well above normal for the month.

A heat wave mid month set some records for humidity in particular. 5 consecutive days exceeded 30°C with 4 of those days seeing dewpoints over 20°C and humidex values near or over 40. Three daily high and high minimum dewpoint records were broken during the heat wave. Most spectacular was a dewpoint of 24.5°C on Aug 15, the latest occurrence of dewpoint over 24°C and the 3rd highest daily dewpoint maximum in August since 1953.

Overall, dewpoint in August averaged 13.7°C, tying with 2003 for 14th most moist since 1953. Interestingly, 10 of the last 16 years had an average August dewpoint in the top 20 highest since 1953 while only 2 were in the top 20 lowest.

With high humidity came high rainfall amounts. 107.8 mm of rain fell at Winnipeg airport, the 22nd rainiest August since 1873 and the rainiest since 2010. Higher totals fell in the southern half of the city with locally close to 150 mm.

Rain and severe thunderstorms

There were 6 thunderstorm days at Winnipeg airport, bang on normal. It was a wet and stormy month overall in the Winnipeg area.

Large hail fell over south Winnipeg on August 7 with hail up to golf ball size. Damage to vehicles and gardens occurred. The same storm later produced a tornado near Anola. That same day, another tornado also reportedly touched down southwest of Swan River around midday.

Heavy thunderstorms brought flooding rains on August 22 to Winnipeg. Up to 50 mm fell in less than 1 hour in parts of the south end. Quarter-size hail, wind gusts to 80 km/h and frequent lightning also occurred, making for quite a storm to remember. Numerous streets and underpasses flooded and some were impassable. Water seeped into and flooded parts of St Vital Mall. Lightning also caused a few fires. The daily total rainfall at the Winnipeg airport was 38.4 mm, breaking the old record of 38.1 mm in 1959 for the day. Over 50 mm fell in the south end, making it one of the wettest days since 2010.

In addition, severe nocturnal thunderstorms also occurred during the overnight hours early on August 22. Winnipeg was spared the worst with only minor rainfall amounts and frequent lightning. Cottage country north of the city was not as lucky. A swath of quarter to softball size hail fell from Teulon to Matlock to Beaconia to Pine Falls. Major damage occurred, especially in the Grand Marais to Beaconia region where one person reported that every single vehicle outdoors during the storm was severely damaged. 50+ mm of rain also fell in the area within 1 hour, making for quite a storm. The largest hail reported was a 4-inch diameter hail stone near Powerview.

By Breanna Victoria near Altona Aug 28

Large and damaging nocturnal hailers occurred once again early on August 28, this time southwest of Winnipeg. Toonie-size hail and larger fell from Austin to Ste. Claude to Roseisle to Plum Coulee to Altona. The Plum Coulee to Altona region was hardest hit with hail up to baseball-size. Major damage occurred in Altona with broken windshields and siding, flattened and shredded plants/trees, damaged crops, dented vehicles and took down some small branches. The storm also dumped about 26 mm of rain, causing some street flooding.