Pleasant midweek weather gives way to Friday rain chances

Noticeably Cooler:

Cooler, drier air filtered in as yesterday progressed, allowing temperatures to start 10 to 15 degrees lower than they did Tuesday morning. The drop in humidity is also making for a much more comfortable and refreshing start to the day. 

  

Warm, but Dry Wednesday:

High pressure settling in nearby will provide plenty of sunshine throughout the day. While afternoon highs will end up similar to Tuesday, lower humidity levels will make a noticeable difference. Dew points are expected to remain in the upper 50s and low 60s, resulting in a comfortably warm afternoon with much less mugginess across the Stateline.  

Friday's Rain Chances:

Sunshine continues for Thursday, though high pressure will gradually give way to our next weather maker by Friday. While this system appears fairly weak, increasing cloud cover is expected Thursday night into Friday morning. 

Scattered rain showers will then develop and push in by mid to late morning Friday and continue at times through the afternoon. Again, if you are heading to day 3 of the Ogle County Fair or Day 1 of Festa, plan accordingly. It may be wise to have an umbrella with you.    

Why was there condensation on my window Monday morning?

 

Did you wake up Monday morning (yesterday) and wonder why your windows were wet? All the windows in our house had quite a bit of condensation on them. It's a pretty simple reason and really highlights the dew point temperature.

It doesn't happen all that often but tends to occur more on very warm and humid summer nights (like Sunday night/Monday morning). We cool the air on the inside of our house with our AC. That, in turn, cools the window. When the warm and humid air that is outside hits the cooled window the air begins to cool, reaching the dew point temperature. Since our dew points were pretty high that night the air didn't have far to cool. When that cooling takes place, condensation occurs. Think of it just like the dew that occurs on the grass in the morning. Or the condensation that forms on your car window when it's hot and humid outside and you have the air running.

And as long as the moisture is on the exterior part of the window - your window is doing its job. If it is in the middle, well then, you may need to replace some windows.

Hazy skies return thanks to upper-level smoke

 

Summer smoke makes a return to our Stateline skies Tuesday thanks to the northwest position of the jet stream and a passing cold front late Monday night/Tuesday morning. But unlike our last bout with wildfire smoke, most of this smoke will remain in the upper levels of the atmosphere. There will still be some impacts to our air quality over the next couple of days as we remain in the moderate category. For the current air quality and forecasts, you can click here.

The smoke is coming from fires over the Pacific Northwest as a ridge of high pressure sits across the southern Plains. This continues to bring high heat to the south but allows the smoke to move across some of the northwest, Plains, and across the Great Lakes. Thanks to an upper-level inversion in our atmosphere that smoke isn't able to easily mix down to the surface, although there may be some that tries late Wednesday and Thursday. This may be more of an issue to our west than for us locally.

As our winds remain positioned from the northwest in the jet stream, we will likely continue to see at least some smoke impact our skies throughout the week.

What you'll notice more of, however, will be the reddish sky during the sunrise and sunset. This has to do with the smoke particles in the atmosphere, scattering more of the blue/violent light wavelengths. Those wavelengths are shorter and tend to scatter easily, leaving behind the red and orange light wavelengths. And because the sun's light has a longer distance to travel through our atmosphere during sunrise and sunset, more of the blue/violet light gets scattered, leaving behind the red. Depending on the thickness of smoke this could leave us with a very vibrant sunrise/sunset, or more of muted one.

Intense heat takes a back seat as July comes to a close

Hottest Day of the Year:

Monday (as of right now) is written in the books as the hottest day of the year for northern Illinois and southern Wisconsin. Temperatures soared into the mid to upper 90s for most locations. Combined with the tropical humidity and dew point temperatures in the upper 70s, heat indices climbed to very dangerous levels between 110° and 120°.  

While yesterday's heat sure was extreme, it's not the hottest we've been in recent years. For example, the Rockford airport recorded its first 100-degree day in a decade when the temperature reach 100 degrees on June 14th, 2022. Prior to that, the city had not hit or seen the century mark since 2012. 

  

Cooler, Less Humid Tuesday:

The good news is that yesterday's intense heat appears to be the peak of this most recent stretch, as afternoon highs are set to take a "chill pill". Thanks to a cold front that swept through the region Monday evening, highs today will be much closer to where they should be for late July, topping out in the low 80s. While the day will begin on a muggy note, noticeably drier air will filter in behind the front. 

Rain Chances Increase Late:

This stretch of comfortable weather should make for a rather great start to the Ogle County Fair, which gets underway Wednesday, July 29th, with dry conditions expected through the first few days. As we head into the latter half of the week, however, rain chances will begin to creep back into the forecast. Days 3 and 4 of the fair, along with days 1 and 2 of Festa Italiana at Boylan High School, could see a few showers as a weak system tracks to our south and west.  

Limited thunderstorm chances Monday evening

 

Numerous severe thunderstorms moved around the Stateline late Monday morning and afternoon, prompted several severe thunderstorm and tornado warnings. The storms formed along the outer edges of the high heat, humidity, and instability and were very quick to intensify across Wisconsin and northeast Illinois. There were several reports of large hail, damaging winds, and tornadoes. This left the majority of the immediate viewing area high and dry, and just plain hot and humid! Peak heat index values reached upwards of 115 degrees during the afternoon, with a couple sites even coming close to 120!

While our focus has been on the heat and humidity this afternoon, there are a few showers that are starting to develop along a couple outflow boundaries this evening located across Rock County. A few showers have popped between Janesville and Beloit and are drifting to the south/southeast.

Should the showers continue to develop there is still enough heat and instability to allow for an isolated storm or two through 9pm. And with the amount of instability a severe storm or two cannot be ruled out. So, with that I think our highest chance for thunderstorms (still around 20-30 percent coverage) will be along and east of I-39 through late evening. Should any storm reach severe limits, strong wind gusts and very heavy rainfall can't be ruled out. I'll be keeping a close eye on radar over the next couple of hours.

  

Extreme heat, storm potential also on the table across northern Illinois

Extreme Heat Warning:

Along with the dense fog potential, we also have extreme heat and the threat for strong to severe storms on the table today. Storms will be possible during the morning hours, with a secondary round potentially developing during the late afternoon hours. 

In addition, Winnebago, Stephenson, Jo-Daviess, Carroll, Ogle, Lee, DeKalb, and Whiteside County are under an extreme heat warning until 9PM, where heat index values could climb well into the triple-digits. The rest of the Stateline, including Boone and McHenry counties in northern Illinois as well as much of southern Wisconsin, have been placed under a heat advisory.  

Hot & Humid Monday:

Temperatures are expected to soar into the 90s once again today, and when combined with dew points in the mid to upper 70s, it will feel even hotter outside. These tropical levels of humidity will push heat index values into the 105 to 115 degree range this afternoon, creating dangerous conditions for anyone spending long periods of time outdoors. 

If you do have outdoor plans today, be sure to drink plenty of water, even if you don't feel thirsty. Take frequent breaks in air-conditioned buildings or shaded area, wear lightweight clothing, and avoid strenuous activities during the hottest part of the afternoon.  

Severe Storm Update:

Today's severe weather threat will be fueled by the extremely warm, humid, and unstable air in place ahead of southeastward-diving area of low pressure and the associated cold front. 

With lots of moisture, instability, and lift in the atmosphere, the environment will be conducive for a few strong to severe storms. Though there isn't much going on across Wisconsin at the time of this article, we'll still going to keep a chance for a few isolated storms during the early morning hours. However, forecast models have shifted the main thunderstorm potential towards the midday and early-afternoon hours. The Storm Prediction Center has placed much of the Stateline under a level 3 of 5 Enhanced Risk, indicating the potential for numerous severe storms capable of producing damaging winds and an isolated tornado or two. Make sure to stay weather aware throughout the day and have multiple ways to receive severe weather alerts.   

Dense fog advisory for all of northern Illinois until 8AM

What's Ahead: 

It's a busy start to the work week across the Stateline, and it all begins with very dense fog. 

 

 

   

Dense Fog Advisory:

A Dense Fog Advisory is in place for the entire area until 8AM, with visibility dropping to a quarter mile or less at times. The thick fog will make for difficult travel conditions during the morning commute, so be sure to slow down, use low-beam headlights, and allow for extra travel time. Conditions will gradually improve after sunrise as the dense fog begins to lift and visibility improves.