By Richard McGuire
South Okanagan residents may have to wait a while yet before they see a real reprieve from the bitter temperatures that have gripped the region for more than a month.
Environment Canada Meteorologist Alyssa Charbonneau said temperatures will again dip this week, after warming up slightly this past weekend.
By this coming weekend, however, the cold temperatures may ease.
“After cooling down through the middle of this week, the long-range forecast now shows temperatures warming, beginning this weekend, with a return to temperatures closer to seasonal normal by Sunday,” she said on Monday.
The chilly temperatures through most of December and into January have made this winter one of the toughest ones in recent years. But it certainly hasn’t shattered any records – it just seems cold and long compared to the milder winters of recent years.
The normal mean temperature for Osoyoos in December is around -0.7 C, said Charbonneau. This year, however, it’s been -4.1 C.
The mean temperatures take the average temperatures throughout the day for the entire month.
A difference of around three degrees may not seem like a lot, but it’s actually quite significant, Charbonneau said.
“So definitely it was colder than a normal December,” she said.
Nonetheless, looking back at previous winters, this December wasn’t even among the top 10 coldest.
Because historical data for Osoyoos isn’t complete, Charbonneau looked at figures for other centres in the Southern Interior to identify some of the colder years.
The coldest December on record in Kelowna was a tie between 1971 and 1981 with an average temperature of -8 C.
In comparison, this December the average was -5.3 C. The normal for Kelowna in December is -2.7 C.
Records for Kelowna date back to 1961.
The coldest December on record for Kamloops was 1927 when the average temperature was -10 C. The second coldest was 1971, when it was -9.6 C. This December it was -7.1.
Records for Kamloops date back to 1890.
Charbonneau notes that these numbers are not official.
The colder trend this year may in part be due to a shift in tropical Pacific Ocean currents from an El Niño pattern last year to a La Niña pattern this year.
“We are in a La Niña year and that does typically lead to cooler, snowier conditions,” said Charbonneau. “Last year was a strong El Niño, which was probably part of the reason why we’re feeling such a big contrast this year coming off of last year where things were much warmer.”
Typical variations in the atmosphere are also at play, she said.
“Last winter was fairly mild,” she said. “Compared to recent winters [this winter] is definitely colder than normal, even if it isn’t record-breaking. But it has been a long duration to the cold, so once it cooled down, we haven’t really had a nice warm-up to break things up before getting back into the deep freeze again.”
We’ve had several periods of Arctic air moving south. Normally there are periods of warm, moist air from the southwest off the Pacific to provide relief from these cold periods.
“This year we haven’t seen a return to the more typical pattern where storms coming off the Pacific come from the west and push warmer air into the Southern Interior,” Charbonneau said.
The milder weather this past weekend marked a bit of a return to this Pacific influence, which also brought some snow, she said.
While forecasts last week looked at weather up to the middle of the month, Charbonneau noted that as they look farther ahead, forecasts become less reliable.
“So we kind of look for trends into what might be coming, and that trend right now is just things staying as they have been, colder than normal,” she said.