Widespread frost tonight, elevated surfaces could become slick

 Friday was a chilly day in the Stateline despite the abundant sunshine. The afternoon high of 49 degrees marked the coolest high since we saw only 44 degrees April 7th, over 200 days ago!

A clear sky tonight will work to enhance radiational cooling, where the solar radiation built up from the day escapes into space. This will lead to a cold night with overnight lows in the upper 20s! A bit of surface moisture will likely allow for a widespread frost to develop. A few elevated surfaces (such as decks or balconies) may become slick! I do not expect any issues to roadways, however.

This weekend will start on a cool note again, as afternoon highs will only rebound to the low 50s Saturday afternoon, but near 60 on Sunday. A few passing upper level clouds will not block out too much sunshine. While not as cold, overnight lows will remain in the 30s the couple nights to follow.

Stateline weather whiplash: 20s tonight, near 60 Sunday

Mild Nights No More:

With how mild this fall has been, freezing overnight temperatures have been hard to come by. In fact, we here in Rockford have only recorded one morning low at or below freezing so far this season. 

That all changes tonight. After a partly cloudy Friday with afternoon highs in the upper 40s, temperatures will tumble quickly after sunset as colder air settles into northern Illinois and southern Wisconsin. Low temperatures are expected to drop into the upper 20s, making it the coldest night of the season thus far and setting the stage for some frost by sunrise Saturday morning. Those with any remaining sensitive plants outdoors will want to take the necessary precautions before heading to bed this evening. 

Mild Weekend:

Fortunately, the taste of winter won't stick around for long. While temperatures plunge into the upper 20s tonight, milder air quickly returns for the rest of the weekend. Saturday will feature mainly sunny skies with afternoon highs in the low 50s. 

Temperatures will settle into the low 30s by Sunday morning, allowing another round of patchy frost to be possible, particularly in areas that dip closer to the freezing mark. After a chilly start, temperatures rebound nicely by Sunday afternoon, with highs returning to around the 60-degree mark. This mild stretch continues into next week as we hold onto ridging and a southwesterly wind.

Thursday chill continues, Increasing showers by evening

 

As a cold front now moves into southern Wisconsin and northern Illinois we are beginning to see a few pockets of drizzle, mist, and light showers developing. This precipitation will continue through the rest of the afternoon and evening, coming to an end slowly during the overnight.

Temperatures have remained on the chilly side, although right around where we should be for the average high temperature. Once the cold front clears

the Stateline later this evening a push of cold air is set to move in, bringing temperatures a few thousand feet above the surface below zero. However, temperatures at the surface won't nearly be that cold, although we could see overnight lows dip into the mid-30s. But that chill all depends on just how fast the clouds from the overnight clear out. If the clouds hold tight through the morning, then temperatures won't be quite as cold. If, though, clouds clear before sunrise then there may be a couple hour window where temperatures fall into the low to mid 30s.

I suppose if there is some good news to look at going into Friday it is we should see a return of sunshine as the pesky low clouds finally depart for the afternoon.

Brief dip in temperatures by the end of the week

 
Temperatures will take a little bit of a tumble by the end of the week as a push of colder air arrives Thursday night. This cooler air mass arrives behind a cold front that'll move through the region Thursday afternoon. Temperatures Thursday will only warm to the low 50s thanks to cloud cover and a wind shift around to the northwest. Winds will be gusty at times around 20-25 mph.

As the clouds begin to clear late Thursday night a much cooler air mass will move in causing temperatures to fall into the 30s early Friday morning. Should clouds be a little slower to leave then overnight lows will remain in the upper 30s. If, however, clouds clear a little faster into Friday morning then temperatures could fall into the low 30s. Despite the sunshine expected for Friday, afternoon temperatures will only reach the upper 40s/low 50s.

High pressure to our north Friday afternoon will sink into northern Missouri Friday night allowing temperatures to fall into the upper 20s early Saturday morning. Frost will be likely in the morning, but since the growing season has ended the issuance of any frost or freeze headlines are done for the fall season. While the next few nights will be chilly, they won't be too far from where the average low should be - in the low to mid 30s. Low temperatures the last several nights (and really for the last couple of weeks) have been mainly above average, with the last few nights well above average! So, while yes, it will feel chilly heading into the weekend we are not too far off from the average.  

Steady drizzle/light showers Wednesday afternoon

 

Temperatures are quite a bit cooler Wednesday following a cold front that came through during the morning. The front, while bringing an end to the steady rain, has allowed a much cooler air mass to settle into northern Illinois and southern Wisconsin. Temperatures as of 3pm are currently in the low 50s.

Clouds are in an abundance this afternoon thanks to low pressure spinning over Minnesota. This has sent several weaker low-pressure systems down through Iowa, Wisconsin, and northern Illinois resulting in widely scattered drizzle and/or very light showers. In some instances, the drizzle has actually been a little on the heavier side, reducing visibility from time to time. This drizzle/showery pattern is what we can expect for the remainder of the afternoon and evening as gusty southwest winds continue through Thursday morning.

A stronger upper-level low will move across northern Illinois Thursday morning and this will allow for a few widely scattered showers to develop and move in during the early morning commute. Similar to Wednesday, cloud cover Thursday afternoon will hold afternoon highs in the low to mid 50s continuing the very fall like look and feel.

Rain, wind, then frost? The Stateline's weather roller coaster continues

Unsettled Election Day:

Tuesday turned out to be a rather unsettled day across the Stateline, bringing everything from periods of rain to gusty winds. Most locations picked up between a quarter to a half inch of rain, providing some with a beneficial rainfall. Adding to the soggy weather were brisk southerly winds, which gusted from 30 to 35 mph at times. This made for an interesting drive and walk to the polls for those who went. 

Remaining Breezy:

While conditions won't be nearly as soggy today, we do hold on to quite a bit of cloud cover as well as those gusty winds. Winds will shift to the southwest today and tonight, frequently gusting up to 30 mph during the daytime before easing slightly to 25 mph tonight into Thursday morning.   

Another wind shift arrives Thursday afternoon as a secondary cold front sweeps through the area, turning winds to the northwest. At times, winds could still be as high as 25 mph, leaving afternoon highs in the mid 50s. Low pressure will continue to spiral nearby as it exits into the Great Lakes, keeping a chance for a few passing showers. The best opportunity today will be to our northwest, then shifting to the local area during the day Thursday. 

Cooler Nights Ahead:

Cooler air arriving on the backside of Thursday's cold front and the departing low-pressure system will set the stage for several chilly nights. The coldest period appears to be Friday night into Saturday morning, when temperatures could, keyword COULD, flirt with the upper 20s in some locations. If readings fall that low, area of frost will certainly be a concern, especially in low-lying and open areas. Saturday night and Sunday night won't be as chilly.

Election Day rainfall update

10:35pm: Steady and heavy rainfall is moving into northern Illinois and will continue through about Midnight, with a few showers lasting until 2am. An additional 0.25-0.5 inches can be expected - with a few spots between 0.5-0.75 inches.

8:45pm: Steady rain is beginning to move up through the I-39 corridor, lifting south to north late Tuesday evening. These showers will continue to expand across northern Illinois within the next 1-2 hours. There may still be some isolated thunder with any of the taller rain showers through 11pm.

6:30pm: A few showers continue to lift through northern Illinois and southern Wisconsin this evening, but not quite as heavy as earlier in the afternoon.

A line of showers approaching west-central Illinois will be capable of producing some heavy downpours, along with a couple of isolated thunderstorms. Main area of impact for those storms will be near Carroll and Whiteside counties over the next hour. We should see rain coverage increase again after 8pm/9pm

3:30pm: Scattered showers continue to come down across the Stateline, but a little less in coverage than just a couple hours ago. As moisture continues to lift north ahead of low pressure, currently moving towards south-central Iowa, scattered showers will continue into the evening. The threat for thunderstorms remains the highest west of the Mississippi River where there is slightly higher instability. This is also the area that will remain closer to the center of the low. A few rumbles of thunder cannot be ruled out locally this evening, but we are not looking at any severe threat

1:30pm: Widespread rain continues to come down across northern Illinois and southern Wisconsin this afternoon. Embedded within have been a few pockets of heavier rain.

These steady rain showers will remain fairly persistent through much of the afternoon and evening, adding up at least another quarter to three quarters of an inch of rain. As the surface low moves a little closer this evening, I wouldn't be surprised to hear a

few rumbles of thunder, but any risk for severe weather remains low. Below are some of the rainfall totals as of Midnight, up through 1pm.