Incoming high pressure brought all the smoke and haze down toward the surface for Thursday, limiting air quality and visibility at times. High pressure brings sinking air, working to trap that smoke near the surface. With high pressure overhead, some of this smoke and haze will linger into the weekend.
But that high pressure will also keep a lot of the humidity at bay for a few more days, with high temperatures only reaching the low 80s by the weekend. We slowly climb back near average (mid-80s) toward the middle of the week.
The high pressure also keeps most of the rain away, as we look to see a mainly dry forecast at least through the weekend. The only tiny chance for rain through Sunday comes in the form of a couple isolated sprinkles Friday morning.
Eventually, moisture and rain chances will make a return as the high pressure weakens and slides off to the East. As we build in this higher moisture from the West, we will see a slow increase in rain and storm chances, along with humidity. Scattered coverage of rain looks to start Monday night into Tuesday.
The Air Quality Alert has been extended for both Wisconsin and Illinois through Friday, lasting until Noon for southern Wisconsin and Friday night for northern Illinois. Significant impacts from the Canadian wildfire smoke have caused not only visibility to fall within the 2–5 mile range across the region but has also dropped air quality to unhealthy levels.
This could especially be a concern and have an impact on those with pulmonary or respiratory disease such as asthma, or anyone with breathing issues.
At the unhealthy level it is suggested that those who are impacted reduce prolonged activities or any long duration outdoors.
Smoke from the Canadian wildfires has been impacting many across the Upper Midwest and Great Lakes the last few days, now sinking south following Wednesday's cold front and incoming high pressure. This has allowed the smoke aloft to be pushed down close to the surface reducing not only surface visibility but causing a significant impact on our air quality.
We will likely see the smoke remain across the Midwest and Great Lakes through at least Friday, if not extending a little bit into the weekend, especially aloft. But unhealthy air quality is forecast to last through Friday across the Great Lakes, including the Stateline.
Air quality sensors across northern Illinois have fallen 150, meaning air quality is now "unhealthy".
People with heart or lung issues, older adults, and children should avoid strenuous outdoor activities and consider moving physical activities indoors.
Visibility has also been dropping. As of 6:45AM, locales such as Galena, Janesville, and Rockford are observing values below 3 miles.
Out with the rain chances and in with the Canadian wildfire smoke. Yes, we will unfortunately be seeing a lot of smoke drift our way as we round out the work week, resulting in hazy skies, low visibility at times, and of course lower air quality.
In fact, air quality levels across Wisconsin are sitting in the "unhealthy" category as of 4AM, leaving northern Illinois under the "unhealthy for some" category. You can
check the current and forecast air quality here: https://gispub.epa.gov/airnow/.
Thursday begins with a bit of clouds, though an area of high pressure sliding to our north should get rid of most of those clouds by the afternoon.
This will be a hazy sunshine as some wildfire smoke will end up trapped underneath this high pressure system, resulting in hazy skies.
With a northeasterly breeze in place, expect afternoon highs to end up in a similar range to Wednesday, in the upper 70s. More of the same for Friday. Though that sounds nice, limited air quality could be a
concern both days. So unfortunately, while the air will be comfortable enough to open up the windows, smoke and haze may be too thick to
open windows at least for a couple days.
Wildfire smoke will filter in from the North overnight, bringing limited visibility and poor air quality to the region tomorrow. Below is a view from some of the smoke overtop of downtown Minneapolis Wednesday evening. Smoke locally may not quite get this dense, but we could see a similar picture locally tomorrow. Visibility across parts of Minnesota and Wisconsin was limited to below 5 miles, with some of the smoke reaching toward the surface.
Air quality has been significantly limited within the areas under the most dense wildfire smoke. The air quality index in parts of Wisconsin and Minnesota has reached the "unhealthy" category as of 6PM Wednesday, and some of this will shift Southward overnight into Thursday. You can check the current and forecast air quality here: https://gispub.epa.gov/airnow/
Wildfire smoke will shift into our region following the exit of the rain and clouds tonight. Smoke could get trapped under the incoming high pressure, which may keep some of the smoke and haze around the area through at least Thursday and into Friday. Limited air quality could be a concern both days, so unfortunately even though temperatures will be comfortable enough to open windows, smoke and haze may be too thick to open windows at least for a couple days.
There have been several rounds of showers and thunderstorms that have moved through the Stateline Wednesday, with the most recent producing pockets of steady rainfall throughout northern Illinois and southern Wisconsin.
This latest activity is in response to an area of low pressure moving through central Illinois. The rain will continue for the next couple of hours, slowly tapering off through Midnight. Skies will remain mostly cloudy through the night before clearing Thursday as high pressure builds across the Upper Midwest. Overnight lows will fall into the low 60s, climbing into the mid and upper 70s Thursday.
With all the moisture in place Wednesday humidity levels were still high, despite the actual air temperature staying in the 70s. There were even a few locations that stayed in the 60s. Temperatures for the next few days will remain in the upper 70s to low 80s, with overnight lows falling into the 50s.
Arcus clouds are a low, horizontal cloud formation that are typically associated with the leading edge of a thunderstorm or gust front. There are two types of arcus clouds, a shelf cloud and a roll cloud, both of which we have seen this morning.
What's the difference? Well, shelf clouds are attached to the base of
the thunderstorm whereas roll clouds are detached and form separately.
How do these form? Ahead of these storms is a very warm and humid air mass. As rain falls
from the incoming storms it works to cool the surrounding air, causing
that air to surge out ahead of the storms.
This rain, cooled air –
because it is more dense – will then push the warm, humid air ahead of
it up and over. This process causes clouds to form, giving us the shelf
appearance.
Shelf clouds aren't associated with anything tornadic, though you will encounter some pretty strong winds, heavy downpours, and frequent cloud to ground lightning once it passes overhead.
Redevelopment is possible this afternoon as an area of low pressure slides to our south.
The severe risk is low, though I would still have multiple ways to receive watches and warnings as any severe thunderstorm will be capable of producing damaging winds up to 60 mph.
Tagging along with today's severe potential is another plume of Canadian wildfire smoke. An air quality alert has been issued for the state of Wisconsin until 12PM
Thursday. Those who are sensitive to unhealthy air quality will want to limit time outdoors until the air quality improves
Otherwise, clouds and a northeasterly breeze will limit afternoon highs to the low 80s. In fact, we can say goodbye to the "dog days of summer" as both temperatures and humidity levels become comfortable into the first weekend of August.
That is great news for those attending Festa Italiana at Boylan High School this weekend!
A complex of sub-severe and severe storms is moving over the Mississippi prior to sunrise.
As of right now, there is one severe thunderstorm warning and that is for locales in southwestern Carroll and western Whiteside County. This is for 60 mph winds and runs until 5AM.
** WARNING CANCELLED**
Strong thunderstorms over Jo-Daviess County will still be capable of producing 50 mph winds and minor flooding as they move east. Timing this portion of the line out puts them in Freeport around 5:13AM and Rockford closer to 6AM.
Written by First Warn Weather Intern Mitchell Marti
An air quality alert has been issued for southern Wisconsin until Noon Thursday. Smoke from the wildfires in Canada will lead to unhealthy air quality for sensitive groups. According to the Wisconsin Department of Natural Resources, smoke from the Canadian wildfires has been observed in northern Wisconsin this morning. The smoke is expected to slowly move south into southern Wisconsin by noon Wednesday. The smoke will then linger over the state until noon Thursday and then will move back into northern areas Friday.
Those who are a little more sensitive to unhealthy air quality will want to limit time outdoors until the air quality improves.
Tuesday will have a similar start to yesterday with early morning rain coming in, however it looks to be even weaker than yesterday where scattered thunderstorms developed through the morning.
Showers and thunderstorms have continued to weaken this morning as they've approached the region due to them losing instability as they move east. At one point these rain showers were once strong thunderstorms in Central Iowa where numerous Severe Thunderstorm Warnings were issued overnight. However, through the rest of the morning we'll see light rainfall with this system as it moves through.
It'll still be another hot day today though as we'll be right back in the 90's for the third day in a row. It's been a humid stretch and expect that to continue today as dewpoint temperatures will once again be in the 70's which will bring our heat index values near 95-100°. Once the morning showers and thunderstorms move out, partly cloudy skies will return into the afternoon!
Heading into the night and into tomorrow morning a cold front is expected to move through bringing relief for the rest of the week. A much drier pattern is expected to develop while temperatures look to stay in the upper 70's to low 80's.
Before that though, with the cold front moving in tonight/tomorrow this will help develop showers and possible thunderstorms through the day tomorrow. Although cooler, we could see widespread rainfall tomorrow bringing rainfall totals near an inch in some spots. However, this cold front will also dry out any available moisture for the next few days which will keep us dry!
Into next week, our upper-level ridge that gave us such warm temperatures this weekend will shift to our southwest taking both warmer temperatures and available moisture with it. This combined with weak upper-level winds will keep us dry through most of early next week while comfortable temperatures will return for the start of August!
For the seventh time this month the high temperature reached 90 degrees, or above, with Monday's high reaching 93. Combine that with dew points that were in the 70s all afternoon and it felt more like temperatures were close to 100 degrees.
The rain and thunderstorms from the morning were quick to move out leaving skies mostly sunny for most of the afternoon. A few thunderstorms developed well east of the Stateline, closer to the suburbs and Chicago, along a lake breeze and numerous outflow boundaries. A couple of those boundaries did stretch as far west as Winnebago County, but our skies remained dry.
Temperatures won't fall much through the night as we maintain a very warm and humid air mass. Overnight lows will only dip into the low 70s. A Severe Thunderstorm Watch has been issued just to our west until 4am Tuesday for an ongoing thunderstorm complex producing very strong winds over northwest Iowa. Another storm complex is currently moving east of Minneapolis into Wisconsin. Both storm complexes are moving to the southeast and will likely impact at least a portion of the viewing area early Tuesday morning.
The storms should slowly weaken through the night but there will likely be just enough instability to maintain at least the threat for some strong, gusty winds in southwest Wisconsin and northwest Illinois during the pre-dawn hours Tuesday. We remain under a marginal risk for isolated severe weather, primarily for strong winds, through Tuesday morning.
Depending on how long the storms stick around will have an impact on how hot temperatures get during the afternoon. Right now, it looks like we should clear quick enough to allow highs to warm back into the upper 80s, close to 90 degrees, with the heat index back into the mid-90s. Thunderstorms will be possible once again Tuesday night and Wednesday ahead of a cold front that'll clear the region Wednesday evening. Once it does, a much more comfortable air mass will be in place through the end of the week. The only thing we may need to watch out for would be the smoke and haze from the wildfires in Canada. We may end up with a few hazy days following the cold front.
Overnight a large, organized complex of thunderstorms developed over portions of Minnesota and through the night has made its way into portions of Iowa as well as Southern Wisconsin and Northern Illinois. Although not severe, a few strong thunderstorms may be possible early this morning.
As of 4:30 a.m. this complex is much less organized than before however the northern fringe may still pack a punch in some spots. Right now, very consistent lightning and heavy downpours will be the main concern as these thunderstorms move slowly east this morning. A few stronger wind gusts (40-50 mph) may also be possible in the strongest storms.
The Storm Prediction Center has kept their Marginal 1/5 severe thunderstorm risk over the state line this morning for the possibility of an isolated severe thunderstorm. Strong wind gusts continue to be the primary concern, however, as noted storms have begun a weakening trend.
The bigger story today will be the heat once again. Heat Advisories have been issued across the region lasting until 8 p.m. tonight for the possibility of head index values reaching 105°. It'll be another day of heat and humidity so heat safety will be crucial for those outside, so make sure to stay hydrated and take frequent breaks in the shade!
We could also see a bit of relief from the heat today depending on how long rain/cloud cover sticks around behind the thunderstorms this morning. But dewpoint temperatures are expected to reach the low 70's into the afternoon while any sunshine behind the morning storms will quickly increase temperatures back up into the low 90's!
Upcoming thunderstorm chances for the next few overnights will likely have a big impact on the degree of heat and humidity coming the day after. After a hot and humid Sunday in the Stateline, we could be looking at our first of a few nighttime storm chances late tonight. Each round of storms will be weakening as they approach the area but could bring pockets of gusty winds and heavy rain within the strongest pockets of storms. Each round will also heavily influence the daytime humidity and storm chances.
The first potential round of storms will arrive after 2-3AM tonight in a weakening fashion, with some staying dry into the morning. These storms do not look to linger long, but an isolated shower/storm may be possible as late as 9AM. If we see stronger storms for the morning, this could hinder recovery of humidity by the afternoon, while weaker or no morning round may indicate a hotter afternoon with only very isolated thunderstorm chances. At the moment, the latter of the two solutions looks most plausible.
We should dry out for the afternoon, with temperatures rebounding to the low 90s and dew points rebounding to the upper 70s. This would mean peak heat index values will rise near or above 100°. A heat advisory will be in effect area-wide from 12-8PM Monday for this potential.
A very similar risk for storms will develop again Monday night into Tuesday morning. Like the night before, storms will arrive well after midnight and could linger into the mid-morning hours. These storms would again pose a risk for gusty winds and heavy rain. If they fizzle or clear quicker, the afternoon could bring an isolated risk for additional thunderstorms. Either way, temperatures will rise back near 90° with dew points in the mid-70s Tuesday, placing heat index near 100°. Another heat advisory may be needed for Tuesday.
Best coverage of showers and storms will arrive Tuesday night into Wednesday morning as a cold front approaches the region. These storms may again pose a risk for gusty winds and very heavy rainfall, and these may linger into Wednesday afternoon. With the front pushing South by then, high temperatures will hover near or just below 80° Wednesday. We will dry out Wednesday night as high pressure and a much drier air mass settles in to take us through the end of the week.
A Dense Fog Advisory has been issued for Green, Rock, and Walworth counties in southern Wisconsin and for Stephenson, Jo Daviess, and Carroll counties in northwest Illinois until 9am. Within the last hour visibility has fallen down close to zero in some of the outlying and rural locations.
Please be careful if you're out traveling this morning as you'll likely encounter quickly changing visibility. It'll take a couple hours before we begin to see
improvements. Visibility will gradually improve through the 9am hour.
Aside from an isolated shower or storm mainly South of I-88, we should stay dry into the evening. Temperatures will gradually fall to the low 70s, meeting the dew point under a calm wind. This could develop some areas of fog after midnight. Visibility could drop below a mile, especially near and Northwest of Rockford. Any fog should fade away by mid-morning tomorrow.
Temperatures will quickly rise near 90 degrees for Sunday's high temperature. That paired with dew points back in the low and mid-70s will push the heat index near 100° at times. Monday will be even hotter with low 90s temperatures and dew points pushing the upper 70s. Heat index Monday could reach near 105° at times, which may prompt another heat advisory. Slow improvements arrive by the middle of the week, with a much more pleasant air mass arriving after Wednesday.
The heat and humidity may also bring a risk for isolated thunderstorms. The daytime hours of Sunday and Monday look primarily dry, but storm chances may be present Sunday and Monday nights. There is still a lot of uncertainty of exact timing and placement of these complexes, but the support for a couple weakening complexes both nights.
The first one arrives after midnight Monday morning, with storms diving Southwest from Minnesota and Northern Wisconsin. Highest potential for severe weather is focused well to the North where there is better confidence on the strength of those storms, but a Level 1/5 Marginal risk for severe weather is in place for parts of the Stateline for Sunday night/Monday morning.
Another very similar complex of storms may develop across the Plains Monday evening and slide our direction overnight. These storms may be a bit delated from the night before, arriving after 2AM. But again, the focus will be on if the storms can maintain their strength into the night. A Level 1/5 Marginal risk for severe weather lies to our Northwest for Monday night/Tuesday morning.
