Another nasty weather forecast prompted the Rochester School District to announce on Friday that classes would be canceled on Monday. The National Weather Service has included the Rochester area in a winter storm watch from early Sunday morning through noon on Monday because of the possibility of near blizzard-like conditions followed by another blast of arctic air.  Forecasters are predicting a developing storm system will bring 2 to 4 inches of snow to southeastern Minnesota Saturday night. Some light snow is also possible Sunday, but the main problem will be blowing and drifting snow caused by strong northwest winds that could gust above 40 mph.  The temperature is expected to slide through the day on Sunday and could reach 20 below Monday morning, while the daytime high Monday is expected to be between 5 and 15 below zero with wind chills reaching -40 or colder.