Temperatures Sunday afternoon warmed into the mid and upper 50s under a partly cloudy sky. Skies will remain partly cloudy through the night as temperatures fall back into the upper 30s. A cold front moving through will turn winds to the northeast Monday as cloud cover slowly increases during the day. Highs on Monday will warm to the upper 50s.
A few showers are possible during the afternoon and evening, with isolated thunderstorms Monday night. This is as the cold front lifts back north as a warm front. Strong low pressure developing to the west will draw the warm front north as it moves from the Plains, into the Midwest. There is a low-end risk for a few stronger storms south of Rockford during that time. Right now, hail appears to be the biggest threat.
Elevated thunderstorms may be ongoing during the morning Tuesday. Like Monday night, hail will be a possibility. Temperatures on Tuesday will depend heavily on the placement of the warm front. Highs will warm to the 70s south of the front, but only to the 50s north. It looks like the warm front may make it as far north as the state line before stalling out during the afternoon and evening.
We continue to monitor the potential for another round of severe weather Tuesday afternoon and evening. Dealing with another round of dangerous weather is difficult just days after a devastating storm, so here is what we know now:
A warm front will be the dividing line between warm and humid air to the south and cooler air to the north. As of Sunday evening, the Stateline appears to be right on that border. A strong low-pressure system, formed by a strong jet stream aloft, will move into the Midwest Tuesday evening. A few thunderstorms are possible during the morning, with those posing a low risk for severe weather. The risk for severe thunderstorms may increase during the late afternoon and evening, but there are some factors that could limit just how far east of the Mississippi River those storms will reach. Behind the warm front the atmosphere will become capped, meaning air at the surface will have a hard time rising. If the cap holds throughout the day, the risk for thunderstorms will be lower locally. If, however, the cap breaks the amount of instability (energy) in the atmosphere would allow thunderstorms to quickly develop and turn severe. The setup Tuesday is not identically to the setup we had last Friday. While there is a strong warm front, cold front and low-pressure system, some of the dynamics in the upper-levels of the atmosphere are a little different. The strongest winds in the jet stream are a little further west than they were on Friday. If this remains the case, the highest risk for storms may reside west of the Mississippi River. The system as a whole appears to be slowly down just a little, not bringing the cold front through until early Wednesday morning. This means we may not see storms until late Tuesday night/early Wednesday morning. Nonetheless, the risk is there and one we should continue to pay attention to. Be sure to stay updated with the forecast throughout the next couple of days because changes are likely to occur.