The clouds were slow to clear for some Tuesday, holding temperatures in the mid and upper 60s for much of the afternoon. Where the sun was able to shine most of the day, highs reached the low 70s. By Tuesday evening the southern edge of the cloud deck was right along the state line, with a few higher level clouds streaming in from the southwest.
Under a partly cloudy sky Tuesday night temperatures will settle into the low 50s. With little spread between the dew point and air temperature, areas of patchy fog will be possible by Wednesday morning. Cloud cover will continue to increase during the morning as a strong Fall storm system east of the Rockies will lift northeast into the Plains and Upper Midwest Wednesday afternoon and evening.
This low will pull a cold front through the central Plains, reaching the Mississippi River by Wednesday evening. A warm front will lie just to our southwest for much of the day Wednesday. Strengthening winds in the lower levels of the atmosphere, known as the low level jet, will be increasing through the morning and afternoon, pulling in more moisture to the Stateline. This will eventually lead to showers developing mid to late morning over west-central Illinois, lifting through southern Wisconsin by early afternoon. Expect showers and isolated thunderstorms to increase in coverage between 10am and 12pm. No severe weather is expected.
We may see a little break in some of the rain during the early afternoon before the warm front lifts through between 5pm and 8pm. During that time we will briefly be in the ‘warm sector’ of the storm system. Thunderstorms are forecast to form along the cold front west of the Mississippi River and quickly arc northeast ahead of the front. If this occurs we could possibly see a few storms move in, especially over our southwest counties of Whiteside, Carroll, Lee and Ogle, some of which could be strong to severe. Like Monday, risks would include strong wind gusts and isolated tornadoes.
The entire area is under a marginal risk for severe weather, which while on the lower end of the scale, still needs to be watched closely as these Fall systems can definitely pack a punch. Our window for strong/severe potential will be from roughly 5pm to 9pm/10pm.