CS Forecast Maps

IL: Some activity in far northern IL has developed this evening, storms aren't necessarily favored to become severe, but a stronger one or two is possible before the storms dissipate after dusk. Friday will feature a similar environment, with again showers/storms favoring northern IL, where a marginal risk of severe storms exists, which looks reasonable although many areas may end up dry due to more scattered nature of storms, but the strongest ones may be locally severe. Saturday may have a better risk of severe storms with a risk area highlighted on Day 3's map in far northern IL where a Slight risk has been issued in their SPC outlook, with the Enhanced risk in Wisconsin. This is accurate with afternoon timing there and later arrival towards northern IL, where instability will diminish with southeast extent, but still potential through northern half of state as moderate (1500 J/kg) instability and around 30 kts of shear may exist to keep some activity severe. Southern half of state is most likely dry with guidance showing none/little in the way of rainfall.

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Chicago Southland: Periodic chances of showers/storms will exist from today through the weekend, we are on the edge of a heatwave across the Plains, so the activity we will be seeing for the next few days are due to the ring of fire pattern that sets up over our area, as disturbances, known as ridge riders, continually move along the edge of the heatwave, best severe weather potential may come Saturday night as CAPE values nearing 2000 J/kg, 25-40 kts of shear, and dewpoints near 70F combine to favor severe weather in our area, while the better potential for storms exists northwest of us due to more favorable diurnal timing, a risk upgrade could be possible in our area if confidence increases. PWATs near 2" also suggest flash flooding potential in our area with a marginal risk of flash flooding for Days 2 and 3 according to WPC.