A surging mass of mild Pacific air will be spilling over the Rockies into Alberta and western SK over the next few days, while Manitoba remains entrenched in cold Arctic air. Temperatures will rise above zero over much of southern and central Alberta today through the weekend, while temperatures of -20 to -30 prevail over the eastern Prairies. The dividing line between these two distinct airmasses will set up from northern Alberta into western North Dakota, with occasional clippers moving along this boundary bringing bouts of snow that will clip southern MB from time to time, especially over southwest sections. Long range guidance is hinting that this dividing line will shift east into southern MB next week with moderating temperatures and a chance of snow.
In the meantime, be prepared for very cold conditions today into tonight over southern Manitoba as an Arctic ridge builds in. Temperatures this afternoon in Winnipeg will struggle to the -23C mark but the good news is that winds will be dropping off as the ridge builds in, so windchill won't be a significant issue this afternoon into this evening. Temperatures however will plummet into the low -30s this evening as the ridge moves over the red River valley (note this ridge brought temperatures of -35 to -40C this morning over western MB and eastern SK) The coldest temperatures will be this evening then look for rising temperatures overnight as clouds move in and winds pick up from the south. Those winds however will bring increasing wind chills once again, with values near -40 overnight into early Friday morning.