Tuesday, 30 December 2014

#10, #9 & #8 - Top 10 Weather Stories of 2014 in The Winnipeg Area

#10 - July in May: Record Heat & Numerous Thunderstorms Late May 


     After an April-like first 2/3rds of May, Mother Nature had a dramatic mood swing on May 22 when the weather abruptly became July-like for the remainder of the month. Daytime highs exceeded 20°C on all but one day and exceeded 25°C on 7 days. 2 super-hot days exceeded 32°C, the most 32°C days in May since 1995 when we also had 2 days. Just 10 days after we saw snow we reached 33.3°C on May 24, breaking the old record of 32.7°C in 1980. It was the hottest day in May since a high of 33.7°C on May 30, 1995 and the first 30°C day in May since 2007. Surprisingly, it was also the hottest day of 2014! The last time our hottest day of the year was outside the summer months of June, July or August was in 2004 with a high of 31.2°C on September 19. The last time the hottest day of the year was in May was in 1994 with a high of 31.8°C on May 18.

     With the heat came thunderstorms. Multiple rounds of thunderstorms occurred throughout southern Manitoba May 24th to 29th. After a record hot day in the low to mid 30’s May 24th, thunderstorms formed in the afternoon in the Winnipeg area (see radar loop). Crashing thunder and heavy downpours occurred with generally 5-15 mm in the city. 27 mm fell at the St Adolphe MAFRI station to the south.

     A trailing line of thunderstorms developed from Emerson to Steinbach close to noon on May 25 and dumped impressive rainfall totals in a short period of time. Generally 20-40 mm of rain fell around Steinbach (see radar loop). According to SteinbachOnline, creeks overflowed and several streets flooded, making travel difficult. 
May 29 looking northwest from TCH near Carberry

     Strong thunderstorms moved into southwestern Manitoba May 26, binging damaging winds, hail and 29 mm of rain in Melita.  

     Trailing thunderstorms again became a problem May 29, this time in southwestern Manitoba. Three rounds of thunderstorms hit the area in the morning and evening, dumping generally 30-40 mm of rain from Melita to Brandon. Locally higher amounts fell, such as in Swan Valley where 51 mm was recorded. According to the Brandon Sun, flooding forced the closure of highway 10 near the town. In Brandon, some streets flooded, there were some power outages and branches were taken down by wind gusts of 70-80 km/h. A photo gallery of the storms in southwestern Manitoba can be seen here.

#9 -  Mid-Fall Warmth & Very Dry Conditions


     After an extended period of cooler conditions and persistent northwesterlies in early October, things turned around mid-month when above normal conditions became dominant.  

     All but two days exceeded 10°C from October 10 to 26. The average high during this 17-day period was 15.5°C, more than 5°C above normal for the period. Two days reached 20°C; October 15 and 24. In fact, a high of 20.6°C on October 24 had not been reached that late in the season since 1990. Despite the above normal conditions, no record daily highs were broken during the warm spell. In the end, the month only averaged 6.7°C, 1.6°C above normal and tied 42nd warmest October since 1872. Cool downs early and late month prevented October from finishing very warm overall.

     The main story of mid fall was the lack of precipitation. No major systems heavily impacted the Red River Valley in October. Only 4.9 mm of precipitation fell at the airport in October, the 3rd driest October on record since 1872. All of this precipitation accumulation fell as rain, the 13th least rainy October.


Table: Top 10 driest Octobers since 1872 in Winnipeg.

Rank
Precipitation
Year (s)
1
2.5 mm
2
2.8 mm
3
4.9 mm
2014
4
5.3 mm
7
5.8 mm
8
6.9 mm
9
8.1 mm
10
8.4 mm

Nov 11 after the first snowfall of the season