Environment Canada says a few isolated thunderstorms moving eastward across the region are expected this afternoon. A strong storm watch is also in effect for the Prescott and Russell area. A severe thunderstorm warning is in effect for Petawawa, Pembroke and Cobden as the storms track east along the Ottawa River Valley, according to the weather service. The weather forecast for the capital calls for a risk of rain and thunderstorms on Saturday afternoon and after midnight. The lowest overnight temperature is 11 C. On Sunday the forecast is mainly cloudy with a chance of rain and the maximum temperature at 20 degrees. Labor Day Monday looks sunny with a high of 23 C. More sunshine is forecast for Tuesday and Wednesday.