Day 4 of Chicago, IL (KORD)

It briefly dipped down to 61F last night during a period of clearing before clouds came back. There was 0.01” of rain with a light shower this morning, with clouds breaking a bit afterward but still pretty cloudy, perhaps a bit more than expected, with a high of 71F. Some clearing is expected this evening with lighter winds, leading to some radiational cooling (with a small chance of it getting below 61F by 06z to count for day 3), but late in the night, the cooling and lingering low-level moisture will lead to low clouds or fog/mist, halting the cool down. It still looks a little cooler than last night. Winds turn to light southeasterly tomorrow with increasing sunshine after some morning low clouds and fog/mist. With sunnier skies and a warmer air mass, tomorrow will get quite a bit warmer than today. However, both the high and low will be sensitive to just how cloudy it is. As the sounding shows, the clouds are only at the low levels with dry air above, which leads to the highest forecast uncertainty. The high will be sensitive how far inland the lake influence extends. I still think to favor the warmer side of model guidance for the high. Although the HRRR is likely too cool, it does illustrate the potential temperature gradient near the lake, with the lakeshore and downtown possibly being 5F or more cooler than KORD. Winds will be rather light for most of the day, but the lake breeze will likely give a slight boost to the wind tomorrow afternoon.

 

Source: PivotalWeather

Source: PivotalWeather