Temperatures Friday afternoon warmed into the upper 80s and low 90s thanks a breezy southwest wind. As dew point temperatures warmed back into the low 70s the heat index was pushed into the low to mid 90s, making it feel rather muggy most of the afternoon. Evening temperatures have dropped some, but with dew points still close to 70 degrees we won’t see temperatures drop too much Saturday morning.
Ongoing thunderstorms, some severe, across the Midwest and Plains will remain well to the northwest through early Saturday morning. As the storms begin to move into Wisconsin around sunrise Saturday, they should be weakening before reaching southern Wisconsin. Just enough instability, however, may support a few of those making it into the Stateline during the morning; severe weather would be rather low at that time. Temperatures Saturday will once again warm into the upper 80s and low 90s, with the forecast high for Rockford reaching 92 degrees.
The heat index, however, is forecast to rise into the upper 90s, to near 100 degrees for some during the afternoon. A Heat Advisory has been issued for Whiteside County in NW Illinois, stretching back into Iowa and Missouri. So far, that is the only county in the region to be placed under the advisory.
Even though the majority of the Stateline isn’t under any sort of heat headline, it’s important to remember heat safety Saturday; take frequent breaks if outdoors for a prolonged period of time, drink plenty of water, take breaks in the shade/air conditioning and try to do any strenuous activities either early in the morning, or towards the evening when the heat isn’t at its peak.
The rise in heat and humidity Saturday could also help fuel a few strong to severe thunderstorms Saturday afternoon and evening. The storms to the north during the morning will be weakening, but could still produce an outflow boundary that, if it develops, would move into the area late morning and afternoon. That combined with the incoming cold front and high levels of instability could allow thunderstorms to quickly develop, some as early as 1pm/2pm Saturday afternoon.
The Storm Prediction Center has placed the entire region under a marginal risk, with a slight risk highlighted for those along and east of I-39. If thunderstorms were to develop they would quickly turn severe with damaging wind gusts, small hail and very heavy rain being the primary threats. As the cold front clears the Stateline Saturday evening, the chance for storms will come to an end around 8pm. Remain weather aware Saturday, especially if you’re out during the afternoon.