Enhanced risk for scattered storms today before cooler air arrives

Smoke Lingers:

Before we dive into the storm threat for later today, we still have some lingering wildfire smoke impacting air quality across the Stateline. In fact, air quality levels in many communities are currently in the "unhealthy for some" category, prompting an Air Quality Alert to remain in effect. 

  

For northern Illinois, the Air Quality Alert remains in effect through today and Monday night. Across our southern Wisconsin locales, their portion of the alert will run until noon today. While conditions are not nearly as severe as some of the smoke events we've experienced this summer, those with respiratory issues, young children, and older adults may still see impacts if spending time outdoors. The good news is that a gradual shift in winds should help improve air quality levels as the week progresses.

Enhanced Risk for Storms:

Turning our attention to the severe weather threat, the Storm Prediction Center has most of northern Illinois under a level 3 of 5 Enhanced Risk for scattered strong to severe storms later today. That said, how things evolve throughout the day, especially during the morning hours, will play a huge role into whether or not we stay active into the evening. 

Forecast models suggests a round of storms could move in late this morning into midday. The overall severe threat appears relatively low, however, a few stronger storms could produce gusty winds. 

And of course with these kind of setups, the initial round will ultimately influence the evening setup in two big ways: by lowering some of the instability and energy needed for stronger storms later on, and by shifting or laying out any boundaries that could become focal points for redevelopment. 

Should the atmosphere recover behind the first round, a second wave of storms will become more likely late this afternoon with potential lingering into the first half of the night tonight. If that occurs, the threat for damaging winds and a few tornadoes would emerge along with the threat for heavy rainfall. Keep tabs on the forecast throughout the day as well as checking the Mystateline+ app for any updates.   

   

Big Changes Follow:

A noticeable change in the weather pattern arrives behind an early-week cold front. As winds shift to the northwest, cooler and less humid air will gradually make it's way into the Stateline. After we see highs climb into the upper 80s today, temperatures will trend downward each day, settling back into the upper 70s by Wednesday afternoon.   

Scattered strong to severe storms possible Monday evening

 Severe storms will be possible Monday afternoon and evening across Wisconsin and Northern Illinois, including a threat for a few tornadoes. Much of the early part of the day will be dry with some lingering wildfire smoke. Air quality will gradually improve through the day as the next weather system brings a stronger Southwest wind by Monday afternoon.

There is a limited chance for a few non-severe storms as early as late morning or early afternoon, but most will end up staying dry. Should those storms develop, they could lay down an outflow boundary on which the next round of storms may initiate. The primary wave of storms will move in after 4PM from the Northwest along a cold front sliding through the area.

Storms could form in clusters or individual supercells. The clusters of storms will have a heightened wind threat, while supercells may have some rotational traits to increase a tornado threat. There are reasonably some regions of the Stateline that end up staying dry. Storms will exit the area to the Southeast after 12-1AM.

There will be a lot of energy for these storms to work with, which is not uncommon for summertime severe setups. There is a little more shear (change in wind speed or direction with height) compared to typical summertime patterns.

As a result, the Storm Prediction Center has placed much of the Stateline under a Level 3/5 Enhanced risk for severe storms. Damaging wind gusts, possibly in excess of 70 mph, will be the primary threat with these storms. Higher risks for tornadoes should be centered across Northern Iowa and Central/Southern Wisconsin where the wind shear is a little better, but a few isolated tornadoes will be possible across the entire area.

As usual, be sure to stay tuned for updates on the forecast through the course of the day tomorrow. Have multiple ways to receive warnings should they get issued. If you go to bed before the end of the storms, make sure those warnings will wake you up. Have a plan ready to go so you know where to go during a severe storm and be ready to execute that plan should a warning be issued.

Wildfire smoke returns Sunday, strong storms possible Monday

 Following Saturday afternoon's cold front, another round of wildfire smoke is set to move in later this evening and overnight. Thickest smoke will arrive toward 11PM-12AM across the I-39 corridor and will spread West from there. This smoke is not quite as dense as the previous round, but air quality will again be impacted once the smoke arrives.

With high pressure taking over into Sunday, smoke will likely linger through the day. While densest smoke may scatter a bit by evening, visibility and air quality will likely remain limited through the course of the day Sunday and into early Monday.

Air quality will once again likely reach "unhealthy" levels Sunday. Much of the area was well into the "hazardous" category Thursday night and Friday, so I don't expect it to be quite that bad, but the AQI (air quality index) will likely reach between 100-200 starting Saturday night and lasting through at least early Monday.

Smoke will begin to clear Monday as our next weather system arrives. Scattered storms will be possible through the course of the day, with higher chances toward late afternoon and evening. Strong to severe storms will be possible with some better organization especially West of the Mississippi River.

The Storm Prediction Center has upgraded portions of Iowa, Minnesota, Wisconsin, and far Northwestern Illinois to a Level 3/5 Enhanced risk for severe storms. The highest threats will be damaging wind gusts within any storms that develop, but an isolated tornado may be possible as well. There are still a lot of fine-tuned details to iron out with this forecast, including how quickly smoke clears out Monday. Be sure to check back for updates!

Saturday afternoon weather update

 [3:45PM] It may not feel like much of a "cold" front, but the front has passed through Rockford. Note the North wind, and noticeable drop in dew points. South of the front, still mid-70s dew points. Behind the front, 60s!

Our thunderstorm chances are dwindling quickly behind the front, but a few isolated storms may remain possible near I-88 through 5PM. Afterwards, we dry out through the evening.

The bigger story then becomes the smoke to return into the region this evening and overnight. Air quality concerns will be likely again tomorrow, but not nearly as dense as the last round of smoke.

Few storms, return of wildfire smoke along cold front Saturday

 Another round of wildfire smoke may be possible this weekend behind a cold front, which could also produce a few isolated storms. This slow-moving cold front will produce isolated to scattered thunderstorms by midday Saturday, between 11AM-4PM. The initiation of storms will depend on where the cold front is located during peak heating. Right now, the highest confidence on storms looks to set up along and South of I-88, where the cold front will settle by afternoon.

Strongest storms will be capable of damaging wind gusts. Small hail is also a possibility, but not a high concern. The Storm Prediction Center has placed Southern parts of the Stateline under a Level 1/5 Marginal risk for severe storms. Higher coverage of severe storms looks to remain well South and East across Indiana, Ohio, and Pennsylvania.

Another impact the cold front will bring is another round of wildfire smoke. As fires continue to burn across Canada, more smoke will spread our direction behind that cold front. The density of this round of smoke is still uncertain, but air quality concerns will be increasingly likely into Sunday morning. High pressure overhead Sunday will result in very little steering aloft, meaning any smoke that is drawn in will be stuck overhead while that high pressure is in place.

Air quality is not a big concern tonight or tomorrow, but Saturday night into Sunday will result in degrading air quality. I don't think smoke will be nearly as dense as the last round, but AQI could reach into the "unhealthy" category from time to time. That round of smoke should clear Monday as our next weather system moves in.

Air quality drops to extremely hazardous levels across northern Illinois

Current Air Quality:

Yesterday's lake breeze helped keep the thickest plume of wildfire smoke at bay for much of Thursday afternoon. However, once the boundary retreated later in the day, denser smoke pushed back into the area, causing air quality to deteriorate significantly across much of the Stateline overnight. 

Rockford's air quality has deteriorated to extremely dangerous levels this morning, with the Air Quality Index (AQI) soaring to 670, more than double the threshold for the "hazardous" category. This level of pollution poses a serious health risk to everyone, not just sensitive groups. If you need to head outdoors early today, limit your time outside as much as possible and consider wearing a properly fitted N95 mask. 

Those most vulnerable, including young children, older adults, and anyone with heart or lung conditions, should remain indoors until air quality improves. Even healthy individuals may experience eye, nose, and throat irritation, coughing, or difficulty breathing if exposed.  

Air Quality Alert:

Similar to yesterday, the EPA has kept most of the Stateline remains under an Air Quality Alert. The portion that contains northern Illinois will be in place through Friday night. Meanwhile, the portion of the alert that contains southern Wisconsin will stay in place until noontime today. 

  

When Will Conditions Improve? 

Skies are expected to remain hazy and smoke-filled through at least the morning hours, with air quality staying poor as smoke lingers near the surface. We should see conditions improve after the midday hours as surface winds take a turn to the southwest. That change in wind direction will help push some of the thicker, more hazardous smoke out of the northern Illinois area, leading to improving visibility and air quality as the afternoon progresses. 

Another Round?

Looking ahead to the weekend, a cold front is shown sweeping through Saturday afternoon. Behind it, we see a swap to a northwesterly surface wind, which may usher another plume of wildfire smoke into the Great Lakes by Sunday. As a result, hazy skies could once again grab weather headlines and the Stateline's air quality levels may take another hit.  

Wildfire smoke, poor air quality linger through early Friday

 [10:45PM] Rockford's AQI (air quality index) is now up to 508. This is WELL into the "hazardous" category. Highly consider avoiding time outdoors if possible and wearing a mask if you must be out. Even healthy individuals can be seriously affected by smoke this dense. Little change expected through the night, but conditions will rapidly improve by midday Friday.

[9:45PM] Air quality is really, really poor across the area. Rockford is now reporting an AQI of 384, well into the "hazardous" category. Spend as little time outdoors as possible and wear a mask if you must be out. Air quality may not improve much until midday tomorrow.

[9PM] Dense wildfire smoke has pushed as far West as Eastern Jo Daviess, Carroll, and Whiteside Counties. Air quality has degraded to "unhealthy" for the majority of the area with an AQI of 187 in Rockford as of 9PM.

[7:40PM] Wildfire smoke is moving back into Rockford with air quality deteriorating to the "unhealthy" and "very unhealthy" categories once again.

[6:45PM] Air quality is dropping again for our Eastern Counties as a lake breeze pushes in. This will bring the dense wildfire smoke back West through the evening and possibly overnight as well. Current air quality is already degrading quickly across DeKalb, McHenry, and Walworth (WI) Counties, with some AQI back above 200+, placing much of the area East of I-39 under "very unhealthy" or "hazardous" categories.

Wildfire smoke and poor air quality have remained through the course of the day but have shown gradual improvement this afternoon. As of 5PM, the AQI (Air Quality Index) is down to 130 in Rockford, down from 250+ around midday. The worst of that smoke has been on the Eastern side of a lake breeze, which may begin to push back inland over the course of the evening. This will temporarily bring more dense smoke back toward the I-39 corridor through the early part of the night.

Along that lake breeze, a few isolated showers and thunderstorms have developed. Any storm that does form will not last very long in any given location. Coverage of showers and storms will remain limited to the lake breeze, indicating those a county or two East or West of the I-39 corridor may likely stay dry. Storms will diminish after sunset.

As the lake breeze pushes inland tonight, air quality will remain limited. At least patchy smoke remains in place through midday Friday before lifting back North out of the area. Later afternoon and evening of Friday will bring significant improvements from the smokey conditions. The Air Quality Alert now remains in effect through Friday for much of the area, with the exception of Carroll and Whiteside Counties.

While conditions will improve greatly Friday, another round of smoke may be possible Saturday. A passing cold front could draw some wildfire smoke back this direction, but I do not expect it to be nearly as dense as the last round. A few isolated storms may be possible along that cold front as well.