A FROST ADVISORY goes into effect for Stephenson, Jo Daviess, Carroll, Whiteside and Green counties late Friday night, lasting through Saturday morning. Scattered rain showers for much of Friday afternoon were heavy at times, rotating around an upper level low that moved through northern Illinois. While instability was lacking across the immediate area, there were a few thunderstorms that developed just to our southeast.
The tail end of the shower activity is currently moving through north-central Illinois with clearing skies noted to the north. Temperatures, while not record cold highs for May 28th, were cold enough as most of the area only warmed into the mid and upper 40s. The record cold high for this afternoon was 46 degrees set all the way back in 1906! The record low temperature for the 28th is 36 degrees set back in 1949. It’s likely we won’t reach the mid 30s before Midnight, but there could be many spots that fall into the 30s Saturday morning. The record low temperature for May 29th is 33 degrees set back in 1965. Rockford likely won’t get that cold, but some of the outlying areas *could fall into the low 30s.
Cloud cover will continue to clear from north to south as drier air moves in with a southward advancing high pressure system, which currently stretches from northern Wisconsin into northern Iowa. And even though there are several counties that are not included in the advisory, patchy frost is going to be possible for all by morning. Cover up or bring in anything you don’t want to get nipped from the cold. This late season chill does have me a little concerned for the corn and beans in the fields. The growing point for corn is below ground until the five leaf stage, however, much of the corn has emerged and that could take a hit from the cold – especially if we see lows near freezing. Soybeans are a bit more sensitive to the cold and could be impacted more if temperatures tumble that low.
Once the sun comes up Saturday morning we should see temperatures climb rather quickly, warming into the mid and upper 60s by the afternoon.