Air quality drops to unhealthy levels across northern Illinois

Unhealthy Air Quality:

Air quality has taken a noticeable hit across northern Illinois this morning as a thicker plume of Canadian wildfire smoke drifts southward. The combination of smoke aloft and increasing concentration closer to the ground has resulted in significantly hazier skies and more importantly, unhealthy air quality. In Rockford, the Air Quality Index (AQI) has climbed into the "Unhealthy" category, meaning everyone may begin to experience health effects, with sensitive groups facing an even greater risk. If you plan on spending extended time outdoors today, consider limiting any strenuous activities and keep an close eye on air quality levels. 

Air Quality Alert:

As mentioned yesterday, the Air Quality Alert has been expanded to include additional counties across northern Illinois. This portion of the alert will be in place until midnight tonight while those north of the Illinois/Wisconsin border will be under the air quality alert until noontime today. 

 

Thursday: 

Smoke is expected to remain fairly thick across the Stateline through much of the morning and into the early portions of the afternoon, resulting in continued hazy skies and poor air quality. 

 

   

Friday: 

Conditions should gradually improve as we progress through the day Friday as surface winds will change to the southwest. That wind change will help usher in cleaner air into the region, allowing the thickest smoke to begin moving northeast. 

 

Air Quality Alerts expand across northern Illinois as wildfire smoke sinks south

 

Air Quality Alerts have been extended across most of northern Illinois, as well as southern Wisconsin, through Thursday afternoon/evening as Canadian wildfire smoke sinks south into the Stateline late Wednesday night.

Thick smoke from the ongoing wildfires across the border have blanketed most of the northern Great Lakes and Northeast over the last few days. So much so, that visibility has fallen to just a couple miles in
many locations. This has also caused very unhealthy air quality for those from northern Minnesota, Wisconsin, Michigan, and the Northeast.

Through Wednesday evening the wildfire smoke will continue to sink south across Wisconsin before stalling close to the state line and northern Illinois Thursday morning. You can see where the potential for the thickest smoke could reside just around sunrise Thursday.

Throughout the day some of the near surface smoke may mix out, but our skies are likely to remain hazy throughout the afternoon. Some of the near surface smoke may then move back in late Thursday evening, sticking around into Friday morning.

So, what does this all mean for us Thursday? Air quality levels are forecast to be in the 'unhealthy' category, meaning that everyone should reduce

prolonged activities or heavy exertion outdoors. Those with breathing issues or asthma should avoid any sort of prolonged activities outdoors.  

Air quality worsens for some as Canadian wildfire smoke drifts in

Heat Advisory Update:

Another heat advisory has been issued for portions of the Stateline. This time, it includes a few of our northern Illinois counties including Jo-Daviess, Carroll, and Stephenson Counties. This is set to run from 12PM to 8PM today. When you combine high temperatures in the low 90s and dew points on either side of the 70-degree mark, heat indices will wind up in the lower 100s this afternoon.  

Air Quality Alert Update:

Along with the summer heat, periods of wildfire smoke can occasionally drift in, creating concerns when it comes to air quality levels. For that, the EPA has kept McHenry County and the Chicago metro under an Air Quality Alert until midnight. However, added to it is southern Wisconsin which will be under the alert until noon Thursday.   

Air quality as of this morning is already registering at moderate levels and should stay that way as we get into the afternoon. Levels should drift south into the "unhealthy for some" category Thursday. 
 

Hot, Hazy Wednesday:

Similar to the past few days, today will begin with the potential for patchy dense dog. Some, especially out near the Mississippi River, have seen visibility fall to 5 or 6 miles. Use extra caution as some patches will be thicker than others. Due to the fact that we will see some of that wildfire smoke filter in, skies will be hazy but still dry as high pressure remains in control of our atmosphere. Expect highs in the low 90s.  

Smoke filled skies likely for northern Illinois and southern Wisconsin late in the week

 

Numerous wildfires have been ongoing across southern Ontario, filling the skies across southern Canada, the Great Lakes, and Northeast will smoke the last couple of days.

With high pressure nearby, the smoke has also made an appearance locally in the Stateline, although a little more prominent in central Illinois. However, it won't be long until we start to see more smoke not only filtering out the sun the next couple of days but also moving down closer to the surface of the earth.

Air Quality Alerts have been issued for McHenry County through Wednesday evening and for Green, Rock, and Walworth counties until Noon Thursday. I wouldn't be surprised to see those alerts extended both in time and overall coverage as wildfire smoke is currently forecast to shift further down the Great Lakes and Wisconsin, eventually into northern Illinois as early as Wednesday night.

The position of high pressure to our south will essentially cause the incoming smoke to 'stall' close to the state line/northern Illinois through Thursday. The impact of this could very well cause our visibility to drop into Thursday morning, as well as impacting those who have breathing issues or are more susceptible to air pollutants/particulates.

While the heat has taken center stage the last couple of days, and rightfully so, our attention should also be on the potential for increasing smoke through the end of the week.

Heat advisory, air quality alert issued for some

Heat Advisory:

We have a couple of weather alerts to discuss. The first is a HEAT ADVISORY for Green, Walworth, and Rock Counties in southern Wisconsin. This will be in place from 12PM-8PM today.  
 

  

Air Quality Alert:

Another alert in place this morning is an AIR QUALITY ALERT for areas in and around the Chicago metro, including McHenry County, through midnight tonight. According to AirNow.gov, the air quality in and around Rockford is at moderate levels and should remain that way throughout the day. If you are unusually sensitive to particle pollution, consider reducing activity level outdoors.  

Hot Tuesday Ahead:

While no heat alerts have been issued for our area at this time, it's still important to practice if you'll be spending quite a bit of time outdoors. High pressure remains firmly in control, providing plenty of sun and helping afternoon highs climb into the low 90s. That, combined with dew point temperatures in the upper 60s and possibly low 70s will allow our heat indices to hover near the triple-digit mark. 

Staying Hot:

Even though the ridge of high pressure aloft becomes a bit more elongated over the next several days, it remains firmly in entrenched across the central United States and will keep the heat locked in. As a result, afternoon highs are expected to remain in the 90s with little to no rain or storm chances. The center of the high looks to settle directly overhead on Wednesday, which should make it the warmest day of this stretch with afternoon highs in the mid 90s. 

Spotty Rain Thursday?

Again, rain chances remain very slim under this weather pattern. However, a lake breeze boundary may work it's way inland Thursday afternoon and evening, providing enough lift to spark a few isolated showers and thunderstorms. The key word being isolated as many communities across northern Illinois are likely to stay completely dry. Any rain that does manage to develop will be brief and localized, doing little to put a dent in this hot stretch. 

Multiple days in the 90s this week, limited storm chances

 Written By: First Warn Weather Intern Patrick Murray

Strong high pressure overhead will lead to hot, humid and dry conditions for at least the first half of the work week. A Rex-blocking pattern has emerged, and is likely to stick around for the foreseeable future. With this high pressure overhead, we can expect temperatures to soar into the low to mid 90s with dewpoints approaching 70 degrees at times. This will combine to produce heat indices upwards of 105 degrees at times.

Despite daily heat indices potentially reaching 105 degrees, the National Weather Service has held off on any heat-related headlines as of now. This is likely thanks to the fact that only one or two days will really feature those heat indices approaching 105 degrees. As of writing this article, any heat headlines remain well north of the Stateline. We'll have to wait and see if any headlines are issued later for the forecast period.

Unfortunately, not much relief is in sight, as temperatures are expected to remain in the upper 80s/low 90s through the forecast period.

Today, expect temperatures to quickly climb into the low to mid 90s across the Stateline, with heat indices approaching 100-105 degrees. Temps will cool off into the low 70s/upper 60s overnight, providing minimal relief during this period.

Today, expect a high of around 92 degrees with mostly clear skies. A northwest wind at 5-15 mph will help keep things slightly cooler than if we had a south or even southwesterly wind. The next mentionable chance for showers/thunderstorms doesn't look to be until Saturday into Sunday, with a very slight chance for showers and thunderstorms Tuesday through Friday.

How evapotranspiration and mixing will impact the humidity this week

 A blocking high pressure will prevent much abundant moisture from reaching the area, but it will still feel quite humid as the next heat wave sets in this week. How can that be possible with such little rain over the last week? Where is that moisture coming from?

Since we live in the corn belt, a lot of our summertime humidity is actually released by the expansive corn fields. "Corn sweat" is another way to describe evapotranspiration, or the process of moisture evaporating from corn fields into the air, raising humidity levels. One acre of corn can release up to three to four thousand gallons of water into the air each day. All of that added moisture increases the dew point and the humidity which we then feel on hot summer days.

But there will be another feature playing into our upcoming heat wave that may limit the more oppressive humidity levels. That process is called atmospheric mixing. With the very dry ridge of high pressure overhead, there is a lot of very dry air above the surface. Some of that air can be mixed down toward the ground, lowering the humidity a bit. However, since dry air heats up faster than moist air, daily temperatures may rise a bit higher than they would with more abundant moisture.

Our dew points will likely range from the mid-60s to the low 70s most days, which would feel pretty humid especially paired with the incoming heat. Tuesday and Wednesday in particular will be very hot, with temperatures into the low/mid 90s. Wednesday may not quite mix out as much moisture as Tuesday, so I think the heat index may reach a little higher despite a similar temperature forecast. Point being, it will be another hot and humid stretch ahead, so be sure you are practicing heat safety tips including staying hydrated and using lots of sunscreen if you must be out for extended periods of time!