December 2020: Second-snowiest on record for Pittsburgh since 1880

PITTSBURGH — That’s a wrap on December 2020 - and what a month it was for snowfall! Pittsburgh recorded 27.5 inches of snow, making it the second-snowiest December on record. The snowiest December on record goes to 1890, with 41.8 inches of snow.

The snowfall this month was 19.2 inches above average and marks the seventh-snowiest month on record for Pittsburgh. The snowiest month ever on record in the city is February 2010, which recorded 48.7 inches of snow!

Pittsburgh has seen 28.3 inches of snow so far this season, and has already recorded 68% of its average seasonal snowfall. The 28.3 inches of snow marks the fourth-snowiest period for a season to date (October, November, December). The top spot for a season to date goes to 1950 with 51.3 inches of snow.

The entire season, which can run through April, averages 41.4 inches of snow for Pittsburgh.

Snowfall has been abundant so far this season because of the above-average temperatures. The reason is because the warmer weather has kept Lake Erie unfrozen, which can allow for more frequent lake-effect snow events. As of Dec. 31, Lake Erie’s lake-wide surface temperature was 38.92 degrees, and there are parts of the lake near Pennsylvania that ranged up to 45 degrees!

Lake-effect snow forms when colder air blows over warmer lake water. As instability increases, snow showers form. A wind direction from the west or northwest gives us lake-effect snow in our area. Instability is highest when there is a temperature difference of 15 to 25 degrees Celsius between the lake temperature and the temperature at about 5,000 feet. This leads to the best heat and moisture transport in the vertical part of the atmosphere.

Warmer-than-average temperatures are forecast through the first part of January, which will keep Lake Erie warm. As long as it remains unfrozen, it will keep lake-effect snow events in play for our area longer into the winter season.

Streets around Pittsburgh still covered after record Christmas snow

Cox Media Group