Scattered strong to severe storms possible Sunday and Monday

 Multiple rounds of showers and storms will be possible between Sunday morning and Monday, each bringing the threat for severe weather. The first wave of storms won't arrive until midday Sunday, with renewed development into the evening and then again Monday. The main threats will be damaging winds and heavy rain, but an isolated tornado will be possible, particularly Sunday evening where surface convergence sets up following the first round of storms.

SPC has the Level 2/5 Slight risk over most of the area for both Sunday and Monday, indicating the chance for a few severe storms both days. Where thunderstorms track over the same areas over and over, very heavy rainfall will be possible with a risk for flash flooding.

 

As typical for these types of patterns, there are a LOT of moving parts, so be sure to stay tuned to the forecast for the latest! Each round of storms heavily dictates what happens with the next, so the forecast is going to be rather fluid over the next 48 hours.

Hazy skies continue as storm chances return this weekend

Northwest Flow Aloft:

Our weather pattern will become a bit more active as we head into the weekend and next week. A ridge of high pressure building over the western United States and Rocky Mountains will place the Stateline under a northwest flow pattern aloft. That setup often acts as a conveyor belt of quick-moving disturbances to slide southeast through the Midwest.  

While the weekend doesn't look to be a total washout, these disturbances will introduce periodic chances for showers and thunderstorms. Starting with today, the best potential for thunderstorms with disturbance #1 will be to the west and northwest of Rockford, across Wisconsin, Minnesota, and Iowa, hence the Level 1 of 5 Marginal Risk for severe weather. Locally, most of the daylight hours will be dry with showers, and possibly the chance for an isolated thunderstorm or two, sliding in late into Friday night.   

Weekend Forecast:
 
Saturday looks to stay dry for the most part, with high temperatures climbing into the low 80s. The next low is set to move through the northwest flow pattern does not appear particularly strong to start, though forecast models do show it sparking off a round of scattered showers and thunderstorms to the northwest of the area into Sunday. Some of which may track into the Stateline as we approach midday. 

The Storm Prediction Center does have the entire area highlighted under a level 1 of 5 Marginal Risk for an isolated strong thunderstorm or two. Given the time of year and atmospheric profiles, damaging straight-line winds will be the primary concern with any severe storm. Temperatures should remain either near or just above-average in the low 80s. 

Next few days: Humid, hazy, and nighttime rain chances

 The typical summertime humidity will not go anywhere through the weekend and into early next week. Dew points will hover between 65 and 75 throughout nearly all of the next week. While this will not come with oppressive heat alongside, it will feel quite muggy for the foreseeable future.

That humidity will allow for some patches or areas of fog to develop potentially each of the next few nights. Rain chances will also be on the increase heading through the weekend and into early next week. While the daytimes of Friday and Saturday will both likely be dry, Friday night may produce a few storms along a passing cold front. Any severe threat is positioned Northwest of us at this time, but showers and a stray storm may be possible after Friday evening and then again Saturday night into Sunday morning.

The sky will also have a bit more of a haze to it, with a continued feed of Pacific Northwest wildfire smoke. While this smoke will not result in air quality concerns in the near term, the smoke aloft will allow for a milky or hazy sky to take full effect, especially on Saturday when we would see otherwise sunny conditions.

Daytime windows of Friday and Saturday will be dry, but warm and humid with a bit more sunshine compared to recent days. Both Friday and Saturday nights will feature isolated to scattered rain chances, with a few storms possible as well. Sunday and Monday may have more widespread rain and storm chances, including the potential for a few stronger storms.

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.