Fog possible this morning, fair weather through Friday

Severe Pushes South:

The strongest storms yesterday fortunately stayed to the north of the Stateline, impacting much of central and southern Wisconsin. Numerous reports of hail and wind were logged from La Crosse eastward to the Milwaukee metro as the cold front pushed through. There was even a tornado report near Menominee Falls, just northwest of downtown Milwaukee, that will likely be further reviewed by the National Weather Service. Closer to home, severe weather was not an issue, though many saw the leftovers, some heavy downpours during the evening.  

Even better news, today's severe weather potential is highest to the south of the Stateline, leaving us here in northern Illinois under the influence of high pressure and much quieter conditions. 

The one issue or hazard will be present for the start of the day in the form of dense fog, which could reduce visibility for the morning commute. Be sure to use caution on the roads, allow extra travel time, and keep your low-beam headlights on. 

Comfortably Warm Thursday:

This quiet stretch will continue into Thursday as high pressure remains parked over the Great Lakes. Expect partly cloudy skies and comfortable temperatures, with afternoon highs landing in the upper 70s. Humidity levels will stay in check as well, with dew points holding in the low 60s. 

 

Winnebago County Fair:

This will leave days 1 and 2 of the Winnebago County Fair dry, though we'll need to keep an eye on a chance for a few showers, and perhaps an isolated thunderstorms, early Friday. Another chance arrives late Friday into early Saturday as weak cold front move on through. At this point, we are not expecting a washout, but it's something to watch if you plan to spend time at the fair, browse City Market, or Friday night high school football.    

Severe thunderstorm watch issued Tuesday afternoon

 8:35pm Update: The severe thunderstorm watch for Green, Rock, and Walworth counties has been canceled.

6pm Update: Other than a few sprinkles/light showers moving across northern Illinois the last couple of hours, the weather locally has been relatively quiet. However, to the north a line of severe thunderstorms continues to move east/southeast, closing in on south-central and southeast Wisconsin. Further to the west an isolated thunderstorm remains west of the Mississippi River in eastern Iowa.

Between now and 7pm the line of storms to the north should move further south, reaching parts of southern Wisconsin. With instability still around the threat for at least isolated severe thunderstorms, mainly in parts of Rock and Walworth counties, will continue. Instability does decrease slightly south of the state line in northern Illinois, and it is a little unclear at this time if the line of storms will hold together or begin to weaken after 8pm. Regardless, we should see at least a few scattered storms move south of the state line after 8pm. At that time, biggest threats will remain heavy downpours and gusty winds.

2:50pm Update: A Severe Thunderstorm Watch has been issued for the following counties in southern Wisconsin: Green, Rock, and Walworth, as well as for Jo Daviess and Stephenson counties in northwest Illinois until 10pm Tuesday.

Current radar as of 2:50pm shows a few spots worth discussing this afternoon. The first are the showers moving across south-central Wisconsin and north-central Illinois as of right now. These are not severe, and hold a very low risk of turning severe, as they move to the east/southeast.

Storms that are developing northwest of Dubuque could maintain some strength as they moving towards northwest Jo Daviess County within the next hour or two and pose a wind/hail threat.

Thunderstorms further to the northwest across central Wisconsin through La Crosse have formed ahead of the main cold front and, at the moment, hold the highest risk of severe. This line would move in later this afternoon - probably after 8pm or 9pm.

In the short-term - will be watching the second area of thunderstorms (near Dubuque) for an impact on northwest Illinois/southwest Wisconsin through 6pm. 

A brief storm threat gives way to comfortable August weather

What's Ahead:

1. Storm chances increase this afternoon and evening, with an isolated risk for severe weather

2. Dense fog will be a possibility for those traveling Wednesday morning. 

3. Temperatures trend cooler, with the most noticeable drop arriving over the weekend.  

Isolated Severe Tuesday:

The Stateline may see a few showers with the first of two disturbances around the midday hours. However, it is the second wave arriving this evening that will bear watching as the associated cold front could fire up a few thunderstorms, some of which may be strong to severe. While severe weather is not expected to be widespread, an isolated threat does exist, with strong winds being the primary hazard. 

Drying out Wednesday:

Any chance for rain or thunderstorms should come to an end before midnight, leaving us with the potential for dense fog Wednesday morning. If planning to be on the roads, travel with caution.  

After the morning fog lets up, Wednesday is shaping up to be a quiet and pleasant day, with skies turning partly cloudy by the afternoon. Behind tonight's cold front, winds will shift back to the northwest, helping usher in a cooler air mass. That will keep afternoon highs in the upper 70s, providing comfortable conditions for mid-August. 

Winnebago County Fair:

It's also welcoming news fore the final county fair of the summer, the Winnebago County Fair. The chance for rain throughout the fair will be low, allowing most events and activities to stay dry. The only opportunity for rain arrives late Friday into early Saturday as a second cold front sweeps through. Otherwise, expect dry but also cooler-than average conditions as highs remain in the upper 70s into the weekend. 

Scattered storms Tuesday evening, comfortable pattern sticks around

 A couple strong to severe storms may be possible Tuesday evening and the comfortable pattern is here to stay for a bit longer. Starting Tuesday morning, decaying showers and storms may push into the region between 6-9AM but should clear out by midday. Threat for any storms during this time is very low, and most in the region may actually stay dry.

How fast the clouds clear out will determine the severity of the storms into the late afternoon and evening. The main window for storm activity arrives after 2-3PM, continuing through the evening. The strongest storms may be capable of wind gusts around 50-60 mph along with downpours.

Overall severe risks remain limited locally, with the entire Stateline under a Level 1/5 Marginal risk for severe storms. That indicates an isolated storm or two may be able to pulse up near severe limits, but a widespread severe threat is not expected. A few showers and storms may persist into Tuesday night, but even less of a severe risk after 12AM.

Behind that weather system, afternoon high temperatures will hover in the upper 70s each day forward. This will begin a streak of sub-80 degree highs, the first 5+ day stretch since late June! As we get closer to the end of summer, 70s will become much more common than 80s, as the pattern looks to remain near or below average for much of the next couple weeks.

Comfortable air settles in before storm chances return Tuesday

Pleasant Monday:

Temperatures and dew points have taken quite the tumble overnight, providing a refreshing start to both Monday and the new work week. After the recent stretch of muggy conditions, dew points are sitting in the low 60s, with air temperatures also settling into the low 60s early this morning. The result is a much more comfortable feel in the air. 

The pleasant conditions will stick around through the afternoon as an area of high pressure remains firmly in place to our west across Iowa. Aside from a few fair-weather cumulus clouds bubbling up during the peak heating of the day, skies will stay dry and feature a mix of clouds of sunshine. A light northwest breeze will continue to usher in less humid air, helping afternoon highs remain in check. Highs are expected to barely reach the 80-degree mark. 

Storm Chances Return:

Much of Tuesday looks to remain dry as the effects of this high pressure system lingers. That said, changes begin to arrive later in the day as a fast-moving system approaches from the northwest. 

Clouds will gradually increase through the afternoon, with storm chances returns very late in the afternoon and during the evening hours. While widespread severe weather is not expected at this time, a few storms could be strong to severe. As of this morning, the Storm Prediction Center has the entire Stateline under a level 1 of 5 Marginal Risk for severe weather, with damaging winds being the main concern. Conditions should rapidly improve once the disturbance is through, resulting in a quiet but possibly foggy start to our Wednesday. 

 
 

High and dry Monday, storm chances return Tuesday afternoon

 Behind Sunday's cold front, dew point temperatures were dropping into the low 60s and upper 50s through the course of Monday. This much more comfortable air mass will be accompanied by an area of high pressure, keeping us dry through early Tuesday. Afternoon high temperatures with more bountiful sunshine will push back into the low 80s, but without the humidity of Sunday, it will feel much more pleasant.

Our next round of thunderstorms looks to develop Tuesday. An elongated area of low pressure and associated weak cold front will bring a threat for scattered thunderstorms during the afternoon and into the evening. A few of those storms may be strong to severe, with the primary risks of damaging winds and heavy rain.

Scattered storms, heavy rain, and areas of fog possible Saturday night

 [10:40PM] Scattered storms with pockets of heavy rain are developing along a line from about Savanna to McHenry in Northern Illinois. Strongest cells have lightning and rainfall rates above 2" per hour. Storms are moving East at around 15-20 mph. Severe weather is not a concern, but ponding on roadways and low-lying areas will be possible where heaviest rain falls.

[9:50PM] A severe thunderstorm warning has been issued for Southern Whiteside County, IL until 10:45PM. This storm is capable of producing 60 mph wind gusts and very heavy rainfall as it moves to the East at around 45 mph. Worst of the storms will stay along and South of I-88, but isolated pockets of heavy rain will be possible locally as well.

Another round of thunderstorms is developing in Southeastern Iowa, tracking along I-80 once again. A few pockets of heavy rain may lift North of that and into Southern portions of the Stateline through 10PM-1AM. Heavy rain would be the primary threat, with rainfall rates near 1-2" per hour.

Some locations near and North of Rochelle received 2" of rain last night, so flooding threats would be highest if any storm were to pass over that same region again. After 1AM, coverage of rain will wind down, with only a few isolated showers to follow the rest of the night.

Patches or areas of fog will then be possible into Sunday morning. Visibility may be limited at times, with pockets of locally dense fog. Temperatures will return to the mid-80s Sunday afternoon as a cold front clears out some of the cloud cover by the evening.