After several days of oppressive heat and humidity, the worst of the summer sizzle (for now) has finally begun to wither away. Temperatures will trend in the direction of early-July standards, however, the active weather stays put into the weekend.
4th of July weekend also features the opportunity for a few showers and thunderstorms. Forecast models continue to indicated a weak area of low pressure or an M.C.V (Mesoscale Convective Vortex) drifting into Wisconsin during the day.
Thursday marked the 4th day in a row that Rockford reached a high of 91°! During that time, peak heat indices ranged from 100-105°. The last time we saw such a streak of heat was nearly this exact time last year! Typically, average highs are around the mid-80s, so we were 7-8° above average each day!
The next few days will feature a subtle decrease in humidity and heat, but it will still feel like summer over the holiday weekend. High temperatures will likely push close to 90 again Friday, upper 80s Saturday, then low 80s Sunday. Each day will feature at least some isolated to scattered thunderstorm potential, so keep tuned to the radar if you're going to be outdoors for any of the holiday festivities!
The storms are generally moving in the east/northeast direction and are likely to impact southern Wisconsin over the next couple of hours. It is possible that a few of the storms could dip south of the state line into far northern Illinois by 5pm-7pm. If so, there would be a risk for an isolated severe storm or two through sunset.
There were a few minor adjustments made to the Extreme Heat Warning last night. The National Weather Service removed Jo-Daviess, Carroll, and Stephenson Counties from the warning as slightly lower temperatures and heat index values are expected in those areas. However, the rest of the Stateline remains under the Extreme Heat Warning until 12AM Thursday night.
As for today's forecast, a few isolated thunderstorms remain possible early this morning, but much of the day will feature partly cloudy skies. Despite the slight drop in humidity compared to the past few days, high temperatures remain the same, peaking in the low 90s for the 4th consecutive day. When combined with the lingering humidity, heat index values will approach the 100° mark and may briefly rise above it for an hour or two during peak heating hours.
Along with keeping an eye on the heat, watch for severe potential this evening into tonight. Much of that potential will depend on whether the atmosphere can recover following a round of showers and storms that pass through Wisconsin early in the day. It also will depend on if the frontal boundary responsible for redevelopment remains intact or fizzles out as it slides closer to the Illinois/Wisconsin border.
Highest severe threats will be strong winds, along with frequent lightning and heavy downpours. For that, the Storm Prediction Center has areas under a level 2 of 5 Slight Risk for scattered severe storms. They also have a level 2 of 5 Slight Risk in place for the entire Stateline area tomorrow as a secondary boundary sinks south.
For the third day in a row, afternoon temperatures have warmed into the upper 80s and low 90s, with the heat index climbing to 100 (or higher). Extreme Heat Warnings remain in place through tonight for Stephenson, Jo Daviess, Carroll counties and until Thursday night for Whiteside, Rock, Green, Walworth, Winnebago, Boone, Ogle, Lee, DeKalb, and McHenry counties.
Storms are likely to get going over the next few hours from parts of Wisconsin, back through Minnesota and Iowa. This is where the stalled cold front/stationary boundary resides. While most of those storms will remain to our north overnight, the slight shift in the upper-level ridge will set the stage for a little further southward development of any storms tonight. This could lead to an isolated storm or two moving into parts of southern Wisconsin and northern Illinois through sunrise Thursday. The main threat for any severe weather resides to our north, but a gusty storm or two may occur locally should any storms move towards the state line late tonight.
Heading into Thursday evening we'll need to keep an eye on any storm that develops locally as there could be a risk for a severe storm or two. Southern Wisconsin and some of northern Illinois are under a 'slight' risk for severe storms Thursday evening. A 'marginal' risk for an isolated severe storm is in place for Friday. Should any storm reach severe limits it would be capable of producing strong winds and hail.
Historically, the 4th of July is one of the hottest holidays of the year. It is right in the middle of summer, when our average high is in the mid-80s. Recent Independence Day holidays have been more of the same, with an average high of 88 degrees since 2020. Six of the last eight years have featured 90-degree days for the 4th!
This year will be right in line with recent years. Highs will reach the upper 80s with some humidity and isolated to scattered thunderstorm chances. Right now, our forecast high is 87 degrees!
Scattered thunderstorms will be possible from time to time, so it will be a day to watch the radar very closely. Highest coverage of rain appears to be mainly early in the day, with lower coverage toward the evening, but that is subject to change based on any lingering boundaries from previous storm complexes Friday into early Saturday morning. Stay tuned to the forecast for future updates!
There have been no changes when it comes to the heat alerts for the local area. All Stateline counties remain under an Extreme Heat Warning until 12AM Thursday night.
Another hot summer day is on tap for northern Illinois, with afternoon highs climbing back into the low 90s under a mixture of sun and clouds. A warm wind out of the southwest will continue to pull in humid air, leaving dew points temperatures in the low 70s. That added moisture will make it feel even hotter, with heat index values hovering around the triple-digit mark this afternoon.
Like you've done the past few days, be sure to take frequent breaks in the shade or A/C if you have to be outside for a prolonged period of time. Stay hydrated by drinking plenty of fluids not including alcoholic or carbonated/caffeinated beverages.
