Severe potential fades across northern Illinois, quieter days ahead

Active Wednesday:

Yesterday's severe weather unfolded a bit differently than it could have, thanks in large part to a morning round of strong thunderstorms. 

This, like last Thursday, helped take the edge off the atmosphere across northern Illinois by overworking the air mass, limiting how unstable things could have become later in the day, ultimately pushing the more significant threat for severe weather to the south. While conditions were less favorable locally for widespread severe storms, the system still managed to produce one tornado in southern Wisconsin. Details on that tornado, including strength and exact path, will be evaluated in the coming day.  

Less Active Days Ahead 

In the wake of that system, we settle into a much quieter and more tranquil stretch of weather heading into the next couple of day. Partly cloudy skies will help make for a pleasant day overall, with a steady breeze out of the northwest keeping afternoon highs in check. Expect us to top out in the low 70s, still a good amount below late-June standards. While most of today stays dry, a weak system sliding in this evening could spark an isolated shower, but coverage remains limited and impacts minimal. 

Friday brings a subtle warm-up as winds shift more westerly, helping temperatures climb back into the upper 70s, much closer to where we should be for this time in June. Along with the warmer air, we'll also have a chance for a few scattered showers and storms during the afternoon. Coverage, like today, doesn't look to be widespread at this point. 
 
 

Old Settlers Days forecast: Isolated rain chances ahead

 Old Settlers Days will not feature the typical heat and humidity we expect from mid-June, but will have periodic chances for rain. Temperatures will range from the upper 60s Sunday to the upper 70s Saturday. There are a few slim chances for rain Thursday and Friday evenings, with higher coverage of rain possible Sunday.

The chances for rain Thursday and Friday evenings will be relatively limited, with only a few stray showers after 6PM each night. Rainfall does not look to come down very heavy, and many spots will be dry at any given time. But if you're heading out, you'll want to make sure you have the umbrella handy!

Better coverage of rain will be possible Sunday with a broader low-pressure system moving through the region. The center of the low will pass South, keeping any strong storm threat mostly downstate, but a few rumbles of thunder will remain possible locally as well. Sunday may not quite be so favorable a day to be outside, so be sure to make your OSD visits by Saturday if you want nice weather!

Wednesday afternoon weather update for northern Illinois

 

6:46pm Update: New: Severe Thunderstorm Warning for northern Green and northwest Rock counties in southern Wisconsin until 7:45pm. Storm is moving east at 45 mph and capable of producing 60 mph wind gusts.

 

5:45pm Update: A TORNADO WATCH has been issued for Green County in southern Wisconsin until 9pm Wednesday evening. Thunderstorms have developed along what meteorologists refer to as the 'triple point'. This is where a low's warm front, cold front, and occluded front come together. Often times this can help enhance the spin in the lower levels of the atmosphere, which is what has happened with the thunderstorms that have moved into southwest Wisconsin.

While the severe threat remains limited for us this evening, we still do have the cold front and low-pressure system to get through this evening. And that may allow for at least an isolated severe storm to impact part of the viewing area through 9pm.

The showers and thunderstorms from this morning have really kept our atmosphere cool and stable. Current temperatures (as of 1pm) are in the mid and upper 50s with a brisk southeast wind. The storm complex from the morning developed a little further south and has pushed the system's warm front down into central and southern Illinois. While there will likely be some shift in the front to the north it'll more than likely remain in central Illinois, and this is where the highest threat for the more significant severe weather looks to remain.

Accordingly, the Storm Prediction Center shifted both the 'enhanced risk' (level 3/5) and 'moderate risk' (level 4/5) southward a bit. Northern Illinois and southern Wisconsin remain within a 'slight risk' (level 2/5) for the rest of the afternoon and evening.

So, what does this all mean for our weather going forward? We'll continue to see a few scattered showers throughout the afternoon as temperatures are likely to creep back into the 60s. There is some clearing taking place over Iowa with the cloud cover and this is slowly starting to allow some instability to build back north into southern Iowa. As the system's cold front and low pressure move east, we will likely see some higher instability develop along the Mississippi River and into parts of northern Illinois through early afternoon. This will keep at least an isolated severe risk going through about 8pm/9pm locally until the cold front passes. The main hazards with any storm that would turn severe would be primarily wind.

Our window for the next round of thunderstorms we'll need to keep an eye on will be from roughly 5pm/6pm through 8pm/9pm.  

Strong winds possible in the wake of morning thunderstorms

Behind this morning's round of storms, we're now watching for the development of a wake low. This can lead to a quick surge in winds even after the storms move out and push to our south. 

For this, a Special Weather Statement has been issued for the highlighted counties until 12:30PM. These winds can be strong enough to blow around loose objects around, down small tree limbs, and could make travel, especially for high-profile vehicles - a bit more difficult at times. Use extra caution. 

On top of that, the National Weather Service placed Winnebago, Boone, Ogle, Lee, and DeKalb County under a Wind Advisory. 

This will be in place until 1PM this afternoon, mainly for the winds associated with the wake low. 
 

SEVERE THUNDERSTORM WARNING Issued For Portions of Carroll, Whiteside County

 

A SEVERE THUNDERSTORM WARNING has been issued by the NWS for portions of Carroll and Whiteside Counties until 8:30. This storm will be capable of 70 mph wind gusts and spotty small hail. 

Trained weather spotters have reported 70 mph wind gusts with this storm. Some areas have seen 80-90 mph wind gusts. For timing information, see the below graphic.

 

Severe thunderstorm watch issued for some

A Severe Thunderstorm Watch is in effect for Whiteside, Carroll, and Jo Daviess Counties until 11 AM. 

 

 

  

Strong storms to the west across central Iowa will approach these counties, posing a risk for damaging winds and large hail. Stay weather-aware!
 

Heavy rain, severe storms possible across northern Illinois today

Latest on Severe Potential:

Uncertainty #1 with today's severe weather threat is already becoming apparent this morning. A large area of showers and thunderstorms is pushing into portions of eastern Iowa and southwest Wisconsin. 

How long this activity holds together - and how the atmosphere recovers behind it - will play a major role in the Stateline's severe weather potential later today. IF storms linger, they could limit instability, and the added cloud cover and rain may slow the northward push of the warm front. This could ultimately temper with the strength and coverage of severe storms this afternoon and evening. With that being said, today will be a "play it by ear" kind of day. Meaning, we have to monitor and see how things go as the day progresses. 

Heavy downpours is certainly on the table, especially with the batch of storms expected to move through this morning. IF the warm front is able to lift north into the I-88 corridor, all severe weather hazards, including a few tornadoes, would become possible, especially along and south of the front where the ingredients for severe weather is much higher. Even areas north of the warm front could still see severe weather, though the primary threat would lean more towards damaging straight-line winds.   

In the latest outlook, the Storm Prediction Center left much of the region under a level 2 of 5 Slight risk for scattered severe storms with locations along and south of I-88 under a level 3 enhanced risk. Further south, a level 4 of 5 Moderate risk remains in place for those across central Illinois and eastern Indiana. 

  

MyStateline+ App: 

Be sure you have multiple ways to receive watches and warnings throughout the day. Have alerts enabled on your cell phone, NOAA weather radio, and make sure to have the MyStateline+ App downloaded to stay up to date with live coverage. 

  

Cool Thursday:

Behind today's frontal passage, conditions become less active but cooler for Thursday. With a steady west-northwest breeze in place, afternoon highs will be limited to the low 70s once again.