Friday, 8 January 2016

9th Warmest December Fitting End to 9th Warmest Year

It was a tale of two seasons in December. The month began remarkably mild with temperatures more typical of October. By mid month, winter made an abrupt entrance as a parade of snowstorms buried southern Manitoba just days before Christmas.

As mentioned, remarkable warmth started December across southern Manitoba. Temperatures exceeded the freezing mark for 8 to 10 days in Winnipeg during the first half of December. December normally only sees 4 days above freezing according to the 1981-2010 normal. 14-consecutive days from the 3rd to 16th never dropped below -9°C at Winnipeg airport, amazing when you consider this is about the normal high in December. One of the warmest days was on December 3 when temperatures reached 7°C downtown and 4°C at the airport. The only record broken during the warm spell was on December 9 when a high of 5.6°C at the airport broke the old record of 5.1°C in 1990.

The warmth was most impressive where there was no snow cover. 3 to 7 cm of snow was leftover from November in the Winnipeg area and this actually kept temperatures lower than they could have been. Areas without snow cover southwest of the city and in southwestern Manitoba saw much warmer temperatures. Many locations reached double digits and in some cases more than once. In Morden, four days exceeded 10°C, three of which were record highs. The high of 14.2°C on December 4 was the third warmest on record in December since 1904. Some thermometers reportedly reached 15°C, more typical of late September or early October. There wasn't a single snowflake on the ground at the time. A similar milestone was reached in Brandon with a high of 11.1°C on the 4th, the third warmest in December since 1890.

The first half of December (December 1 to 15) averaged -3.0°C at Winnipeg airport, the second warmest first half of December on record since 1872. The warmest was in 1913 with an average of -2.1°C.

Winter set in by December 16. Three snowstorms occurred from the 16th to 23rd, dumping 40 cm of snow in Winnipeg. The biggest snowstorm was on the 16th and 17th when about 20 cm fell in Winnipeg. Strong winds helped carve drifts up to two-feet deep in some spots. 18 cm fell on the 16th alone at the official Charleswood station, breaking the old record of 8.4 cm in 1942 for the day. With all the snow in mid December, travel was difficult. Residential streets were difficult to navigate and vehicles were getting stuck in the snow. Thanks to the snowfall, snow depth in Winnipeg sat at 30 cm on Christmas morning, the deepest snow pack on Christmas day in 15 years (since a 30 cm depth in 2000).

In total, 44.0 cm of snow fell in Winnipeg in December, 83% above normal and the 12th snowiest December on record. With an average mean temperature of -8.1°C, it was also the 9th warmest December on record since 1872. This was 5.4°C above normal.

It was a very warm year across southern Manitoba overall. In Winnipeg, 2015 averaged 4.2°C, the 9th warmest year on record since 1872. Highs averaged 10.1°C, tied 7th warmest. This was only the 9th year since 1872 to see highs averaging in the double digits and the 3rd in the last 10 years.

In terms of precipitation, amounts were very close to normal at the airport. However, other parts of the city saw much more precipitation. At my station in south St Vital, there was 544.0 mm of rain, 120.4 cm of snow and 632.3 mm of precipitation.

More details will be provided in a future post on A Weather Moment so stay tuned.

1 comment:

  1. The number one story of 2015 will come, it is just I'm preparing a post for A Weather Moment. Stay tuned to A Weather Moment in the next few weeks...