Wednesday will be warm and windy in central and southern Alberta with plenty of sunshine and highs in the mid-20s. An abrupt change is on the way as a low-pressure system from the Northwest Territories moves into northern Alberta Wednesday afternoon. Showers and thunderstorms are expected north of Edmonton in the afternoon and evening, and the trailing cold front from that low will sweep across central and southern Alberta overnight. Cold air will flood into the lower half of the province and crash into the warmer Pacific air mass flowing west to east over the southern Rockies. The resulting instability from that cold front will create strong wind gusts overnight and there is the potential for periods of intense lightning. Daytime highs in Calgary are expected to drop nearly 10 degrees from Wednesday to Thursday and winds will shift from a strong westerly flow (20-40 km/h sustained wind speeds) on Wednesday, to a north-northwestly sustained wind on Thursday. A band of precipitation will move over the Trans-Canada Highway from B.C. to Alberta late Wednesday and early Thursday. Isolated rain showers or thunderstorms are possible in Calgary on Thursday and Friday, but accumulations will remain low. Mixed precipitation and/or snow is likely in the higher elevations of the Rockies over the next few nights. Once the cooler weather begins in Calgary on Thursday, there will be little reprieve for at least a week. Daytime highs are forecast to peak between 10 C and 16 C until next weekend.
