Fog this morning, northwest flow brings weekend shower chances

Fog Likely Early:

With that secondary batch of scattered showers and storms moving through late Wednesday afternoon and evening, plenty of moisture leftover has once again allowed fog to develop. This morning however, the fog may become a bit more impactful than what we encountered Wednesday morning. Extra travel time should be built into your morning routine as visibility will fluctuate from locale to locale.  

Once the fog lifts, quiet weather settles into the area behind yesterday's cold front. A stray sprinkle or brief shower can't be ruled out early in the day, but most locations should remain dry. Clouds will gradually decrease as we approach midday, giving way to a mix of clouds and sun for the afternoon. With cooler, less humid air filtering in, temperatures will top out near the 80-degree mark. Expect overnight lows to drop into the low 60s with patchy areas of fog once again being on the table Friday morning. 

Active Northwest Flow:

Looking ahead, the overall weather pattern turns a bit more active as we fall under a northwest flow regime aloft in the atmosphere. This setup will allow a series of quick-moving disturbances to slide southeast across the western Great Lakes, bringing multiple opportunities for rain from time to time through the weekend and into early next week.  

The first wave is expected to arrive Friday evening into Friday night, presenting the chance for a few showers, followed by the second late Saturday into Sunday. The third disturbance then looks to move through late Sunday into Monday, bringing a slightly higher chance for isolated storms.

  
 

Active Northwest pattern continues into mid-August

 After the oppressively hot and humid end to July, August has started on a bit of a cooler note. Only one day so far has reached above the "average" high, with Tuesday reaching 85°. Part of the reason for this subtly cooler stretch has been the pattern aloft.

A Northwest flow has been the dominant feature in the jet stream, resulting in more frequent rain chances and not nearly as much heat and humidity. This type of pattern typically keeps the warmest air locked up over the Southern Plains and Southwest with more prolonged heat below that ridge. On the outer edge, we have frequent waves bring us more chances for rain.

This pattern looks to persist awhile longer into mid-August, as backed up by the Climate Prediction Center outlooks. The outline of that Northwest flow looks to keep subtly cooler than average temperatures along the Great Lakes and Northeastern United States, while most of the country experiences more heat.

Weather systems like to travel along the edge of this pattern, bringing more frequent rain chances along with it. Overall, we might see a little more rainfall than typical between the 11th-15th, similar to the on and off showers we have seen over the last few days.

Showers chances limited Wednesday evening, patchy dense fog possible

 

Our rain chances this evening continue to dwindle as a cold front moves across northern Illinois, eventually stalling to our south overnight. There was a line of showers and thunderstorms that developed late Tuesday night/early Wednesday morning, but the majority of the widespread and heavy rainfall remained to our south. And that's where most of the rain ended up this afternoon and evening. Outside of a few showers and isolated thunderstorms that developed northeast of Rockford, the majority of the region ended up dry.

Now with only a few lingering showers to our east skies are slowly starting to clear to the west. We can see this clearing taking place on several of our SkyTrack cameras Wednesday evening.

This will lead to a partly cloudy sky late this evening. Despite the front moving through there really won't be much of a push of 'drier' air until Thursday afternoon. This will leave our dew points in the 60s with plenty of low-level moisture sticking around. Light winds returning behind the front could set the stage for some areas of fog to develop, some of which could become a little more on the dense side through Thursday morning. If, however, cloud cover sticks around the fog may not develop as quickly or be as dense through morning. Either way, be prepared for some areas of dense fog through the morning commute Thursday.

Temperatures tonight will fall into the low to mid 60s while rising back into the upper 70s, near 80 degrees, Thursday afternoon.

Rainfall returns with slow-moving front; severe threat remains low

Warm, Wet Morning:

We're starting the day on a warm and muggy note across the Stateline after a round of intense showers moved through overnight. The rainfall left a decent amount of moisture behind, and with air temperatures now sitting very close to dew point values, patchy fog has developed in some locales. 

  

Now, we aren't talking about a widespread fog event considering we have another round of scattered rain and storms possibly pushing this morning. However, a locale or two may see visibility drop down towards 5 miles over the next hour or two. 

 

  

Along with the extra travel time, you'll want to an umbrella handy as shower and thunderstorm chances begin to increase after 5-6AM. Severe potential this morning is low. However, the amount of moisture pooling along the approaching cold front will allow heavy downpours to be possible. 

The entire day won't be a washout as forecast models do give us some dry time during the late morning and early afternoon hours. But remember, this may give the atmosphere some time to recover, allowing storm fuel to build ahead of a secondary chance for storms this afternoon. 

Severe Potential: 

For that, the Storm Prediction Center has placed the southern and southwest portion of northern Illinois under a level 1 of 5 Marginal Risk, mainly for strong winds. Any chance for a shower or thunderstorm will push into the first few hours of the night tonight, with chances ending before midnight. By then, the better chance for any rain will push south of I-88, closer to the I-80 corridor along the front. 

Summer Rainfall:

As far as rainfall totals are concerned, most will end up in the .25" to .50" range IF some of the stronger showers are able to sustain strength. That will be a continuation of the somewhat good start we've had to the month of August rainfall-wise. Through the first 4 days, we've observed .46" of rain which is only .06" off the average during that stretch.   

Shower and thunderstorm chances on the rise the next few days

 

It'll be yet another comfortable afternoon today as temperatures are expected to be slightly warmer than yesterday with plenty of sunshine to start. Through the day though expect clouds to gradually build as our next system approaches from the northwest. With this system will come a cold front that will bring precipitation chances tonight lasting through Thursday potentially. 

The first of which will arrive late this evening into tomorrow morning as our next cold front approaches. Through the overnight hours tonight, scattered showers and even an isolated thunderstorm will be possible as this front moves in, however expect conditions to clear by daybreak.

Depending then on how our atmosphere recovers into the afternoon another round of both showers and thunderstorms will be possible. We'll have quite the active storm system around which will easily force showers and thunderstorms as long as our atmosphere is able to build enough energy through Wednesday morning. If this were to occur, another round of showers and thunderstorms would be possible Wednesday afternoon.

Even though chances for showers and thunderstorms will be there almost daily the next few days, severe thunderstorm chances will remain quite low. Tonight's round of storms are expected to stay below severe criteria while tomorrow an isolated severe storm can't be ruled out for areas south of I-88.

Over the next three days this incoming system will offer multiple chances for both showers and thunderstorms. This will offer another chance for higher amounts of rainfall for the region after just another heavy rainfall event last weekend. Thankfully, flash flood potential should remain low over this time, however still pay close attention to when heavier downpours occur. 

High pressure holds strong before a midweek pattern change

Comfortably Warm Monday:

We kicked off the new work week on a pleasantly warm note weather-wise. Plenty of sunshine filled the sky Monday, while temperatures stayed a few degrees below average for early August. 

It was a touch muggy at times, with dew points in the low 60s, but overall, conditions remained comfortable for those that had any late-summer plans.  

Another Quiet Night:

All remains quiet this evening and overnight as high pressure stays firmly in control across the region. A few passing clouds are expected, but overall, skies will remain clear, bringing us the potential for some shallow fog by the morning commute. However, the nature of tonight's fog should not end to the extent of what we saw this morning. Overnight temperatures will fall back into the low 60s, making for another mild but comfortable night. 

Next Cold Front:

Most of Tuesday will remain dry, though we will begin to notice some changes as our next cold front approaches from the northwest. Clouds will gradually increase through the afternoon, signaling the arrival of said frontal boundary. The front is expected to move on through late Tuesday night into the early stages of Wednesday, bringing with it the chance for thunderstorms and heavy downpours.  

Severe Potential is Low:

While a few rumbles of thunder is possible, the latest outlook provided by the Storm Prediction Center does not have us under any severe risk. 

 

  

Same for Wednesday, though our "in-house" model does have a potent cluster coming in during the late-afternoon - early-evening time frame. If more of the severe ingredients work their way in, I could see the Storm Prediction Center expanding that level 1 of 5 Marginal Risk into central Illinois. But for now, keep a close-eye on the forecast as changes are likely as go through Tuesday and into Wednesday.    
 

Locally dense fog to start morning; pleasant conditions into afternoon

 

With calm conditions expected this morning along with dewpoint temperatures close to our actual temperature, locally dense fog will be possible this morning. Due to this, the National Weather Services in Chicago and Quad Cities have issued Special Weather Statements for all of Northern Illinois highlighting the possibility of visibility dropping below a quarter mile. However, conditions should begin to rapidly improve close to 9 a.m.

Through the rest of the afternoon conditions will remain comfortable with temperatures climbing into the low 80’s and humidity conditioning to remain rather comfortable. Sunshine will stick around through most of the day as well, however you may see a bit of haze due to wildfire smoke although we shouldn’t feel any effects down at the surface.

As we roll into the next three days not much is expected to change in terms of the forecast as temperatures will remain in the low 80’s to start the week. Sunshine will stick around the start the week however a mid-week system will help increase precipitation chances into the middle of the week.