This week will be cool and wet across southern Alberta with daytime highs in Calgary forecast to sit between four and 11 degrees below average. A low-pressure system from the Pacific basin will initiate a disturbance late Monday that will impact the southern half of the Rockies, extending into Montana. Scattered and mixed precipitation will fall south of the Alberta-B.C. border Monday night before that system crosses into southeastern British Columbia and southwestern Alberta early Tuesday. Freezing rain is possible in southern Alberta, before cooler air will force that moisture to transition into snow. More persistent snowfall is expected along the foothills Tuesday and Wednesday. A low-pressure system in northeastern Alberta will help steer the low in southern Alberta, potentially enhancing the upsloping effect of the counterclockwise rotation around that southern low. Moisture will continue to be picked up from the west coast and dragged into the lee low (the low-pressure system in southern Alberta) so accumulation totals will likely be highly variable and may be high in some regions. Daytime highs will hover around freezing from Wednesday through Friday, before warming up slightly on Halloween. The normal high in Calgary this time of year is 9 C. The forecast high in Calgary on Saturday and Sunday is 6 C.
