Blowing dust, isolated storms possible across northern Illinois Monday

May the 4th Be With You:

Our weather pattern is embracing the warm side of the force today as unseasonably mild air sweeps into the Stateline ahead of our next cold front. Along with the warmth will come a noticeable breeze, bringing concerns for blowing dust - especially in open and rural areas. And while much of the day will feel like early-summer, the atmosphere may become unsettled later on, with a few storms capable of turning strong to severe during the evening hours. 

The National Weather Service has issued a Special Weather Statement for today's blowing dust threat. Gusty winds combined with dry, exposed soil could lead to sudden reductions in visibility, especially in open and rural areas. This includes Green, Rock, and Walworth Counties in southern Wisconsin, along with all of our counties in northern Illinois. If traveling, be alert for rapidly changing conditions. 

Evening Storm Threat:

As for storms, the entire Stateline is under a Marginal Risk for severe weather today. This means most locations will stay quiet, but isolated storms could pack a punch once they get going. The primary threats will be gusty winds, pockets of large hail, and brief heavy downpours, especially late this afternoon into the evening hours. Not everyone will see a storm, but those that do should be weather aware. 

Much Cooler Tuesday:

This evening's cold front will also bring a noticeable shift in our weather pattern. Behind it, cooler air will quickly settle in, leaving high temperatures in the upper 50s Tuesday and Wednesday.  
 

 

Summer-like afternoon Monday with isolated storms

 While it may only last a day, summer-like warmth will make a return for Monday afternoon as temperatures push into the upper 70s and even near 80 degrees in some locations! That comes with another windy afternoon as Southwest gusts push 30-35 mph at times. Blowing dirt and dust could be another concern in open areas, especially where fields have been tilled already.

We will remain dry throughout the afternoon, but isolated thunderstorms may begin to develop along a cold front by early evening. Storms may initiate between 4-5PM, and linger into the late evening, with highest coverage South of I-88 lasting a bit longer.

Once the front clears the area, storms will be pushed South and out of the Stateline. One computer model pulls storms out as early as 8PM, while others keep isolated storm coverage into the night. Storm coverage will not be very high, only scattered (40-60%) at best. A few showers may linger through the night, but highest coverage will be South of the area into Tuesday morning.

A few of those storms may pose a low-end risk for some damaging wind gusts and large hail. The Storm Prediction Center has placed the Stateline under a Level 1/5 Marginal risk for severe weather, indicating we may see an isolated storm reach severe limits.

Behind the cold front, temperatures quickly drop back below average with afternoon highs in the 50s for a few days next week. This also comes with an isolated shower from time to time, but no single day will be a washout. Thursday looks to bring the highest coverage of showers after Monday night's front, but even that day should feature more dry hours than rainy hours.

Short-term warmup with scattered rain chances

 Despite the cold start to Saturday, temperatures climbed back into the upper 50s for the afternoon highs. We remained dry despite clouds building in during the peak heating of the day. Clouds return again overnight, with a quick-moving wave pushing in from the Northwest. This will bring spotty showers our direction, primarily between 5-10AM. Any given location may only see on and off rain for 3 hours before drying out. About a tenth of an inch may come down.

Once the showers move out by late morning, sunshine returns for the afternoon. Temperatures will climb accordingly, pushing into the upper 60s for some. This will be much closer to average for this time of year. Despite the clear sky the following night, temperatures will only drop toward the low or mid-40s to start off Monday morning.

Monday starts out with a lot of sunshine, pushing temperatures into the mid-70s! But a strong cold front will be knocking on the doorstep by late afternoon, bringing another round of scattered showers and even a low-end chance for some thunderstorms. The severe threat looks very low at this time, with an isolated strong or severe storm possible mainly South of I-80.

Behind Monday's cold front, afternoon highs return to the 50s with isolated rain chances each day, similar to the pattern we were under this previous week. No day will be a washout but could feature on and off showers from time to time. Overnight lows will drop down toward the 30s again several nights next week.

Widespread frost tonight, warming up a bit this weekend

 It was another chilly day in the Stateline with pockets of isolated showers from time to time. Afternoon highs only reached the low to mid-50s for most, about 10-15 degrees cooler than average! As clouds thin out this evening, temperatures will quickly drop into the low 30s for most. Widespread frost is likely under a mostly clear sky and light wind.

Frost/freeze alerts will go into effect tonight and run through Saturday morning. That includes a Freeze Warning for Southern Wisconsin from 12-8AM and Frost Advisory for Northern Illinois from 1-8AM. Protect any sensitive plants that may already be in the ground!

Saturday morning will start with sunshine, but clouds return for the afternoon. While we remain dry, clouds will prevent temperatures from rising much higher than the mid-50s. Sunday brings another jump in temperatures with highs in the 60s but also comes with scattered showers.

May begins with a chill, frost concerns linger

It's Gonna Be MAY:

May brings a big boost in daylight for the Stateline, pushing sunsets after 8PM. By the end of the month, northern Illinois will gain about 50 to 60 minutes of daylight, pushing sunset times closer to 8:30PM. But while evenings grow brighter and brighter, the month kicks off with a lingering chill, reminding us summer isn't here just yet.   

Chilly Friday:

Temperatures will trend even cooler than Wednesday and Thursday with highs reaching the low 50s. A light northwest wind will keep that cool feel in place, and we can't completely rule out a brief sprinkle or shower. An upper-level low lingering over the Great Lakes will send another weak disturbance into the region, keeping clouds around at times but also assisting in today's isolated chance.  

Frost and Freeze Alerts:

Tonight, frost is the main concern. High pressure moving in will help clear skies, allowing temperatures to fall into the low 30s. Green, Rock, and Walworth County have been placed under a FREEZE WARNING whereas northern Illinois has been placed under a FROST ADVISORY. With conditions favorable for frost, be sure to cover or bring in any sensitive or newly planted vegetation.

Weekend Forecast:

As for the weekend, northern Illinois will see a quiet but cool start. Saturday features high pressure, leaving skies partly cloudy with afternoon highs staying in the 50s. Clouds will increase late Saturday into Saturday night as our next storm system approaches. With it will be a scattered rain chance than extends into the first half of Sunday. Temperatures will respond to the newly-introduced southwesterly wind, warming into the mid 60s to wrap up the weekend.   

Frost Advisory issued for some Thursday night

 

Some across northern Illinois and southern Wisconsin woke up to a little frost Thursday morning before clouds rolled in shortly after sunrise. Temperatures dropped into the low 30s where skies were clear a little longer through the night, allowing some of the frost to develop. Where clouds moved in a little earlier, temperatures didn't fall quite as much.

A Frost Advisory will go into effect for southern Wisconsin, including the counties of Green, Rock, and Walworth beginning at Midnight and lasting until 8am Friday. Skies will once again turn partly cloudy overnight allowing temperatures to drop into the low to mid 30s.

Cloud cover will increase during the morning and afternoon as yet another weak low-pressure system moves across northern Illinois, allowing scattered showers to develop during the afternoon and early evening. High temperatures on Friday will warm into the mid 50s.

Another rain chance sneaks in before April ends

Scattered Rain Thursday:

April has delivered no shortage of rain across the northern Illinois area. So far, Rockford has picked up 6.23" inches of rain, keeping the ground soaked and waterways high. And it doesn't look like Mother Nature is finished just yet, with another rain chance lining up before we turn the page to May.  

 

Today's rain will be very similar to the chances we've seen this week, with showers staying scattered and generally light. Because of that, most Stateline locales will only pick up a few hundredths of an inch, with totals staying below a tenth of an inch. Conditions will dry out this evening into tonight, allowing low temperatures to fall into the low 30s. Patchy frost will be a possibility come Friday morning. 

  

Frost Friday Night:

Looking ahead to Friday, quieter but cooler weather settles into northern Illinois. We'll see a mix of sun and clouds, with an isolated sprinkle or shower possible at times, though many will stay dry. Highs will top out in the low 50s, running below-average for this time of year. As skies partially clear into the late-evening and overnight hours, the potential for frost increases into Saturday morning. 

Scattered sprinkles/light rain next couple of days

 

The cooler weather has settled in for the next few days and to go along with the chill will be the daily chance for a few sprinkles/light rain showers. The first of which arrived this afternoon and evening. Locally the precipitation hasn't been much, as most of the steady rain has fallen north of the state line in Wisconsin, but a few sprinkles and light rain showers have dotted the skies across southern Wisconsin and northern Illinois over the last few hours. You can see one of those showers on our SkyTrack camera in Beloit, WI.

The precipitation will come to an end as the sun sets Wednesday evening, leading to partly cloudy skies overnight. As the wind eases tonight the potential for some patchy frost will be possible, especially where temperatures are able to drop into the low to mid 30s.

Temperatures Thursday will once again struggle to make it above the mid/upper 50s under partly sunny skies. Northwest flow within the jet stream will send a few upper-level disturbances our direction, with the next one expected Thursday afternoon. Similar to Wednesday, this will give us a chance for some light precipitation during the afternoon and early evening. Rainfall amounts are not expected to be much - adding up to just under a tenth of an inch - but you may need the jacket or umbrella for a brief time Thursday afternoon.

As the sun sets Thursday night skies will clear out once again allowing temperatures to drop into the low to mid 30s. Patchy frost will be possible early Friday, followed by the chance for some scattered precipitation Friday afternoon. Highs will remain in the mid-50s.

High pressure moving in Friday night will give us a better chance for some widespread frost going into Saturday as temperatures area wide drop back into the low 30s. 

Below‑average chill Today, frost concerns by the weekend

Morning Sprinkles:

Sprinkles, light showers, and cloud cover will hang around early, but we should see improvements slowly spill in as the day progresses. Though we see a mix of clouds and sun, a northwest wind will usher in cooler air, liming afternoon highs to the upper 50s. With a bit of moisture and lift still in place, a brief, isolated sprinkle remains possible later today. 

Tonight, skies will gradually clear and this round of cooler air will continues to spill in. With lighter winds and little cloud cover, temperatures will drop off efficiently, allowing overnight lows to fall back into the upper 30s by Wednesday morning.  

 

  

Chilly Nights Ahead:

Looking further down the road, even cooler nights are on the way. By Friday night into Saturday morning, temperatures may dip low enough to allow patchy frost to develop. If you have any sensitive potted or newly planted vegetation, it would be a good idea to bring them indoors or cover them.  

Light rain showers Tuesday night, cool trends continue through week

 It was a pleasant and seasonable day in the Stateline Tuesday as afternoon high temperatures pushed into the low 60s for most, topping out at 64 in Rockford. This came with a lot of afternoon sunshine, but the evening began an increase in clouds from the West.

Light rain showers are set to follow those clouds, with initial rain pushing in after 8-9PM. Rain will not come down hard, but there may be a couple brief pockets of steady rain at times through the night. Temperatures will only drop into the mid 40s with the clouds and added moisture from falling rain.

The last of the showers will exit after 6-7AM Wednesday. All told, up to 0.25" may come down before Wednesday morning. A very slim chance of a sprinkle may be realized Wednesday afternoon, but most of the day will be dry with highs in the upper 50s.

But the cooler stretch doesn't go anywhere this week. The next 4 days in a row (Wednesday through Saturday) are currently forecast to see afternoon highs fail to reach 60 degrees and remain in the mid or upper 50s. Overnight lows will be accordingly chilly, down in the 30s for a few nights. Depending on cloud coverage and surface winds, we could be in store for some patches of frost Thursday and Friday nights in particular!

Rainy April so far, seasonable conditions today

Very Wet April:

April has lived up to its reputation in Rockford, with enough rain to rank the month as the 6th wettest April on record through 27 days. That same soaking rain from Monday also played a key role in the Stateline's severe weather potential, shifting the highest potential well to the south closer to St. Louis. 

 

Cooler Tuesday:

Looking ahead, conditions across northern Illinois will gradually improve as clouds break apart from west to east. That clearing will come with a noticeable northwest wind, ushering in a cooler, drier air behind Monday's frontal passage. Even with a bit of sunshine, temperatures will top out at seasonable-levels, settling in the low 60s.  

Clouds will increase this evening as a weak system moves in from the northwest. While most of the area will stay dry, there may be just enough lift for a few isolated sprinkles to develop, mainly late this evening into the overnight hours. 

Rain amounts, if any, would be very light, with no impacts expected. Afternoon highs will end up even cooler Wednesday as we keep a cool northwesterly wind, which will limit highs to the upper 50s.

Wake low causes some wind damage following morning storms Monday

 The storms this morning didn't pack much of a punch along the leading edge like thunderstorms typically do. But immediately behind the storms, there was a strong push of Easterly winds called a "wake low". This small-scale area of low pressure can occasionally develop behind an outgoing complex of storms, bringing sharp pressure drops over small areas. Air rushes in to fill the void left behind, causing the strong winds in the wake of those storms.

Weather observer Fred Demeter near Stockton recorded this wake low with a barometer. He measured a drop of 0.3 inches of mercury (7-10 millibars) in barometric pressure in just 10 minutes. That also came with a period of gusty East or Southeast winds, above 50 mph from Fred's measurements.

It wasn't just Stockton that saw the winds either. Much of the area saw at least 40 mph gusts in the wake of those storms. DeKalb, Freeport, and Galena each observed 50+ mph wind gusts. Some scattered tree damage was reported across parts of Rockford with extensive damage in parts of DeKalb and Kane Counties. A 70+ mph wind gust was even reported in Milwaukee with more widespread damage. A wind advisory was issued as this wake low began developing and was upgraded to a high wind warning for DeKalb, McHenry, and Kane Counties once the threat for damaging non-thunderstorm winds was imminent.

While wake lows are not all that common, it is a reminder that strong winds can occur outside of thunderstorms too!

Isolated severe storms remain possible Monday evening

 [11:00PM] Storms are exiting out of the area to the East as of 11PM, allowing conditions to dry out overnight. Behind a cold front, winds will turn to the West, gusting near 25 mph at times. This front will also bring in much cooler air by morning with temperatures pushing into the mid/upper 40s.

[10:00PM] The last of the isolated storms have now pushed East of I-39. While these storms are still not severe, they have continued to produce lightning and pockets of heavy rain. A few instances of gusty winds may be possible. Storms will clear Eastern McHenry County after 11PM.

[8:00PM] This thunderstorm in Eastern Jo Daviess County is not severe, but is capable of producing 50 mph wind gusts and penny sized hail as it moves to the East at around 30 mph. This storm will move near Freeport within the next 20 minutes.

[7:00PM] Scattered thunderstorms continue to progress to the Northeast and will move across the Stateline through 9PM. At the moment, neither area of storms is severe, but both are producing pockets of lightning and heavy rain. If storms intensify any, gusty winds and small hail may also be possible, but severe threats do not appear imminent at this time.

[5:40PM] Thunderstorms in Iowa are beginning to perk up a little bit with an isolated severe storm near Cedar Rapids. Additional storms are also forming along I-80 and pushing Northeast. Scattered storms will remain possible through 8-9PM. Still watching for a lower-end risk for damaging winds and hail within the strongest storms locally.

[4:30PM] The atmosphere is trying to destabilize after the morning round of storms came through. Much better instability is fueling severe warned storms mainly South of I-74, while storm coverage will gradually increase locally through 5-6PM.

Strongest storms may be able to produce gusty winds and small hail, with a relatively lower severe risk. Not out of the woods entirely but heading in the right direction! Last of the storms will exit the area after 9PM, as temperatures fall back to the mid-40s tonight.

Severe weather potential drops, but storm chances linger

Monday's Potential:

As we look ahead to later today, we're continuing to monitor the potential for strong to severe storms. That said, rain expected during the late morning and early afternoon hours may limit how much  the atmosphere can rebound or recharge. Because of this, the Storm Prediction Center has pushed the level 3 enhanced risk farther south, leaving the area under a level 2 slight risk for severe weather.  

It's south of the warm front where the atmosphere will be very favorable for all severe hazards. Locally, we'll be watching how things evolve. IF this morning's rain and thunderstorms end up working the atmosphere over too much, our severe threat could be further reduced as we head into the evening. That said, a few thunderstorms will still be possible into early tonight as a cold front sweeps through the area. 

  

Rainfall-wise, most spots could wind up with .25" to .75", with isolated totals up to 1". Cloud cover should stick around into Tuesday morning, then clear out some as we head into the afternoon. Highs will be limited to the low 60s as winds will remain breezy but cooler out of the west-northwest. 

    

Trending Cooler:

With the cold front coming through, temperatures will trend cooler for the end of April. Normally, we are in the low to mid 60s. With troughing occurring in the upper-levels and northwest flow present at the surface, expect afternoon highs to drop into the upper 50s Wednesday, Thursday, and Friday. This runs 5° to as much as 10° below average.