Timing is everything in this forecast. Daytime highs in southern Alberta and B.C. will sit in the high teens to the low 20s on Wednesday and Thursday. In Calgary, the high will reach 19 C on Wednesday with clear conditions and only a minimal west wind. On Thursday, the high in Calgary will peak at 18 C, but the day will feel different as an incoming low-pressure system starts to edge into the region. Thursday will be more cloudy than Wednesday, and by Thursday night, a moisture-laden air mass will mix with that low in southeastern B.C. Rain will begin to transition to snow and temperatures will drop significantly. The daytime high in Calgary on Friday will be 12-degrees colder than Thursday’s high — and that will be one of the warmer days until at least next weekend. That system will cross over the Rockies late Thursday, and by Friday morning, mixed precipitation is likely in some portions of central and southern Alberta. Rain, mixed precipitation and/or snow will continue for most of the day Friday, with scattered precipitation likely on Saturday and Sunday. Pinpointing the location of the heaviest precipitation accumulations on our side of the Rockies is still difficult and will be until that low enters Alberta. At this point, it looks like the area most likely to see higher totals will be between the Yellowhead Highway and the TransCanada Highway. Some upsloping is likely with this system – meaning the precipitation totals will be highly variable in Alberta, and it is possible Calgary might sit just south of most of it. Behind that low, the mid-latitude Jetstream will ride closer to the southern border of the west, and a “zonal flow” pattern will setup. Temperatures will remain well-below seasonal for at least a week, with daytime highs in Calgary ranging from 1 C to 5 C from Sunday through next Friday. The normal high this time of year is 11 C. The overnight lows will not deviate from normal as much. In Calgary, the low temperatures are expected to range from -5 C to -1 C from Friday to Friday. The normal low this time of year is -2 C.
