Long range 11-9-12
The story to follow in the 0-2 day forecast is the cold front that will be moving across the area Sunday night into Monday morning. There is a possibility of thunderstorms; however, there will most likely be just heavy rain associated with this frontal passage due to the lack of instability. The image below shows vorticity at 500 mb. The front will not move into the our area until Monday, but there will be a strong source of lift from positive vorticity advection Sunday night into early Monday morning as seen below. With the passage of the PVA, there will be heavy rain over most of Illinois and eventually to our area outside of the 2 day forecast. Looking at the 850 temperatures there is very strong gradient at this time, as well. The temperature in our area will be 9 degrees C at 850 and over the plains the temperature is -15 degrees C. This just indicates the strength of this cold front.