Monday will be the warmest day for at least a week with daytime highs in the mid-20s across central and southern Alberta. The conditions will be similar to Sunday, with a mix of sun and cloud and increasing west wind in the afternoon. The daytime highs will start to drop Tuesday as the western edge of a low-pressure system in the eastern Prairies edges into Alberta and connects with an upper trough moving south from the Arctic. This modified cooler air will amplify the effects of the localized developing instability and could lead to moderate to severe thunderstorms across central and southern Alberta. The first storms are likely to develop in the corridor between Edmonton and Calgary early Tuesday afternoon. There is the potential for more organization and/or rapid intensification as these cells track south and east. The greatest threats would include larger-size hail, damaging wind and pockets of intense rainfall. A zonal pattern will emerge over the western Prairies for the rest of the week, suppressing temperatures and likely including periods of scattered showers and/or thunderstorms until at least the end of the weekend. Rain is possible most days but is expected on Saturday and Sunday with accumulations up to 20 millimetres possible in Calgary. The normal daytime high in Calgary this time of year is 20 C with a low of 7 C.
