Cooler, more enjoyable air filters in behind recent cold front

Forecast-wise, there's plenty to be happy about. One, after being placed under three severe thunderstorm watches over a 24 hour period, severe potential steers away from the region the next few days. And two, our most recent frontal passage spells cooler and less humid times moving forward.

Those changes however haven't fully settled in just yet as the cloud cover in place this morning will make for another warm start to the day.

By this afternoon, skies will turn partly cloudy, humidity levels drop, and high temperatures will trend cooler in the low 80s. High pressure sliding into the western Great Lakes will make for a mostly clear night, with temperatures ending up seasonably cool in the upper 50s by daybreak. These changes will really make their presence known Thursday as the air will feel much more comfortable. Highs take a step back as well, landing in the upper 70s.

Moisture pooling in behind a warm front will bring the likelihood for a soggy end to the work week. Of course, with Friday's wet forecast comes the potential for a few strong to severe storms. 

Right now, the Storm Prediction Center has the entire region under a level 1 Marginal Risk, with a slightly higher threat focused to our southwest. Chances will then linger into the early stages of Saturday as the associated cold front slides through.   

Tuesday severe weather update

 After a very active start to the day severe thunderstorm activity is beginning to wane as the morning moves through. Numerous severe thunderstorms warnings have been issued through the early morning however a possible second round is still in place for later today.

Currently much of the region is still under a severe thunderstorm watch however the Storm Prediction Center and local national weather service offices are beginning to cancel this watch as the storm complex moves east. 

Taking a look at the radar all thunderstorms are moving east and out of the area through the rest of the morning. With any continued storms this morning they will run the risks for mainly heavy downpours and intense lightning however some small hail is still possible.

Throughout this afternoon the sun will return behind these storms bringing hot and humid conditions. The Storm Prediction Center still does have a marginal risk for much of the reason for an expected second line to develop this evening. However, as of now most thunderstorm activity begins to move east and begins to slowly weaken. But as we move through into the afternoon, flooding may become a risk as areas have already experienced over an inch of rainfall through this morning with more possibly to come later.

Multiple rounds of storms possible Tuesday, some severe

Severe thunderstorm watches are in place to our north and northeast as a potent Mesoscale Convective System (M.C.S) slides into eastern Wisconsin and Lake Michigan. While the Stateline missed out on the brunt of this line, storms are back-building off it's backside across southwest Wisconsin. Currently, these are non-severe, though are producing 40 mph winds and nickel size hail as they slowly push east towards Green, Rock, and Walworth County. Storm chances with the first round will remain possible into the mid to late morning hours.

A secondary round looks possible late this afternoon into the evening as our next cold front slides in from the north and northwest. 

As of this morning, the Storm Prediction Center has areas between Janesville and Rochelle under a level 1 Marginal Risk while leaving areas south of Rochelle under a level 2 Slight Risk. High CAPE, modest shear, and high moisture will allow additional storms and clusters to develop, posing a risk for damaging winds and heavy downpours. 

A few showers and thunderstorms will remain possible into the early stages of tonight. However, conditions dry out and become less humid as high pressure settles in behind today's cold front. Partly sunny skies will be in place both Wednesday and Thursday, with highs peaking in the low 80s. Rain and storm chances quickly return Friday, which will help cool highs back into the 70s.

 

 

 

 
 

Late Monday evening weather update

 

The severe thunderstorm watch that had been issued for southern Wisconsin and most of northern Illinois earlier Monday evening has been canceled. However, isolated thunderstorms will continue throughout the late evening. The greatest threats with any of these storms will be heavy rainfall and hail. A Flash Flood Warning has been issued for southeast DeKalb County until 3:45am.

Our focus continues to remain on the storms that are developing in northern Wisconsin late Monday night, and their progress to the east and southeast. The latest set of computer guidance has these storms strengthening into a storm complex but moving more east than southeast overnight.

If this occurs the track of the storms would move more into central and east-central Wisconsin, from Green Bay to Milwaukee before moving out over Lake Michigan early Tuesday. This would place the strongest and most damaging wind threat to the north.

Storms may then develop to the west and southwest over northern Illinois around sunrise, still holding on to an isolated wind threat through early morning.

The line of storms would likely move out between 8am and 10am with heat and humidity quick to build in behind. As warm air continues to spread east across the area dew point temperatures are expected to warm into the 70s. This would cause humidity values to increase quite a bit, potentially pushing the heat index close to 100 degrees during the afternoon.

A cold front coming in from the north during the evening would then become the focus for additional thunderstorms after 6pm. The exact placement of those storms would depend on where any outflow boundaries from the early morning storms set up, and where the atmosphere has been able to recharge. This could end up being focused more across northwest Illinois and Iowa, quickly shifting south through west-central Illinois and northern Missouri after sunset.

We'll continue to monitor the storms through the night and into Tuesday morning. Be sure to check back with the forecast during the morning.

 

Timing of severe thunderstorms tomorrow early morning

 Overnight tonight into the early morning hours of tomorrow will be a time to be weather ready and pay attention to alerts as an overnight severe thunderstorm threat looks to impact the region.

Currently the storm prediction center has both an enhanced and slight risk out for the entire region. Within these risks damaging wind gusts will be the primary threat through the early morning however hail and a isolated tornado cannot be ruled out.

Thunderstorm development is currently ongoing in Minnesota and Wisconsin, these thunderstorms will continue to grow and redevelop throughout the evening and will push southeastward through the night. These thunderstorms will be following the axis of instability as this instability will be the fuel for the thunderstorms to persist overnight. By 10 p.m. a line of strong to severe thunderstorms is expected to develop and is forecasted to move southeast into the state line region.

Through the early morning hours tomorrow a large complex known as an MCS (Mesoscale Convective System) is expected to develop and intensify in Wisconsin. The track of these thunderstorms will be determined by the instability that is in place and the "swath" of instability these storms will follow. In the case of an instability axis positioned as shown, this would be an outcome where severe thunderstorms would impact the region.

Timing currently is the hardest part of the forecast as it all depends on how storms progress through Minnesota and Wisconsin. However, with current trends the line of thunderstorms is forecasted to reach the region from 3-5 a.m. bringing severe chances with it. With an instability axis positioned further south further development will be expected creating a flooding risk as well.

By the time the sun is up from 6-7 p.m. thunderstorms are forecasted to be out of the region. Depending on how these storms evolve through the morning hours tomorrow this will then determine the next round of storms that may develop into tomorrow afternoon.

However, the focus is on the early morning hours of Tuesday with the enhanced (level 3/5) risk. Although this is overnight, it will be crucial to have severe weather safety plans in place and make sure your phone volume is on so warnings can be properly heard through the night.

 

 

Storm chances quickly ramp back up following a beautiful Monday

Surveys conducted Sunday by the National Weather Service confirmed 5 tornadoes across southern Wisconsin, including the EF-2 tornado that struck the south side of Janesville. 

Additional information is expected to come about today as surveys continue. Stay tune! 

 

Fortunately, the work week kicks off on a quiet note as high pressure moves overhead. Expect partly sunny skies with highs in the upper 80s. Humidity won't be too much of an issue as dew points this afternoon look to sit in the upper 50s. 

Overnight, our attention will then shift to what occurs to our northwest this evening. An impulse sliding into the state of Minnesota will help spark up a strong line of showers and storms, one of which will take aim at the Stateline early Tuesday morning. 

As of this morning, lots of uncertainties remain including the strength of said M.C.S and where it will eventually end up. In fact, forecast models show a couple of scenarios playing out.

Scenario #1, storms roll through the area early, posing a risk for damaging winds and heavy downpours. This would push the better atmospheric parameters south of the region, resulting in no evening threat. 

Scenario #2, there's enough time between the early-day round and the evening round for the atmosphere to significantly recover. This would increase our chance for severe storms Tuesday evening, with all hazards being on the table. 

Scenario #3, storms back build off the the morning M.C.S and sit over N. Illinois for a good chunk of the morning hours. This would also play a role in limiting the afternoon and evening threat. All in all, monitor the forecast and make sure you have multiple ways to get watches and warnings. 

The Storm Prediction Center has the Stateline under a level 2 of 5 Slight Risk for tonight and Tuesday. Again, the Slight Risk for Tuesday may change as more details come about. The cold front responsible for Tuesday's severe threat will also be responsible for the cooler and quieter times that follow. Wednesday and Thursday feature party sunny skies, lower humidity, and highs on either side of the 80-degree mark. Friday would be the next day to monitor for storm potential.

Heavy rainfall and flooding continue early this week

 After last night's round of severe thunderstorms heavy rainfall has sparked multiple flood warnings and flood watches throughout the state line. Widespread heavy rainfall stuck around for much of the night with training storms or continuously developing storms causing heavy rain to fall on areas for over an hour.

Many areas over the state line received widespread 2–3-inch rainfall which for many in the farming community was well needed. Areas in purple on the map above received 3-4 inches and even more with some areas in McHenry County reaching almost 5-inch rainfall totals.

Currently multiple flood warnings are in effect over multiple counties lasting until 10:15 pm as well as portions of the Rock River in Southern Wisconsin. As well multiple flood watches are in effect in the darker green, these watches last through the next couple days into Tuesday as more rainfall will be expected during the day and evening Tuesday. With this next threat of heavy rain Tuesday more flood warnings may be warranted as combined with the current rainfall totals can cause some enhanced flooding issues.

Taking a look at rainfall chances these next few days both overnight and especially all of Tuesday will be a time to keep an eye out for more rain. Monday overnight a line of showers makes its way through the region however Tuesday again brings the chance of strong to severe thunderstorms, with those very heavy rainfall as well. With multiple rounds of showers and thunderstorms through most of the day, rainfall totals can rise over an inch or more bringing more flooding threats.

With the threat of more heavy rain to come it's important to review some flood safety tips as with heavy downpours water can rise quickly. If a flash flood or flood warning is issued, make sure to get to higher ground and follow the "Turn around don't drown" phrase. Never drive on a flooded roadway as water can be visually deceiving. In most cases only one foot of water is needed to make cars float away, with heavy downpours and strong winds from thunderstorms downing leaves and branches this leads to an enhanced risk of sewers flooding and roadways becoming impassable.

Pay attention to both watches and warnings as water can rise quickly especially in flood prone areas near waterways and lower areas.