Winter is in full swing across North America, with two separate lake-effect snow events occurring since Thanksgiving. Lake effect snow is common in the Great Lakes region and occurs when cold air from Canada flows over the relatively warm waters of the lakes, causing the surface air layer to absorb heat and moisture. This layer of air is warmer than the air above and then begins to rise, cools and condenses into clouds that deposit snow on the windward side of the lakes.

In this particular case, a low pressure system in eastern Canada sucked in very cold Arctic air from the north and dumped it into the northeastern United States. Dry, arctic air blew from the northwest over relatively warmer Lake Erie over Thanksgiving, picking up moisture and depositing snow in areas south and east of the lake. A prevailing band of snow brought snowfall rates of 1 to 3 inches (2.5 to 7.6 cm) per hour to Erie and Crawford counties. About a foot of snow fell in Ashtabula County, Ohio, in the first 12 hours, and by Saturday morning there were reports of more than three feet of snow in far northeastern Ohio and northwestern Pennsylvania. Due to this heavy snowfall, portions of Interstate 86 and 90 were closed on Friday, November 29th.

Over the weekend the snowfall eased as the wind direction changed, but it wasn’t long before the northwest wind returned with more snowfall. Another 30 cm of snow was brought to parts of the previously affected regions. The highest amount of snow recorded in both events was 64 inches (162 cm) in Girard, Pennsylvania.

More lake effect snowfall is expected this week as a winter storm from the south plans to move across the northeastern U.S. on Wednesday and bring a very cold flow from the west and northwest across the Great Lakes through Thursday. Forecast models suggest an additional 3 to 8 inches of snow could be possible in these previously affected regions, as well as east of Lake Ontario. Meanwhile, arctic air just northwest of the Great Lakes is bringing extremely cold temperatures to the city of Winnipeg, Manitoba, with highs of -24°C, which is 17°C to 18°C ​​below normal for this time of year.

In South Africa, citizens are experiencing their third heatwave of the season. The heat wave that began last week is expected to continue into the coming week, with the hottest temperatures expected in the East. One of South Africa’s capitals, Bloemfontein, can expect temperatures of over 35°C every day this week and into the weekend. The hottest days are expected to be Tuesday and Wednesday, when temperatures will peak at just over 40°C, almost 10°C higher than the climate average for those days.