September to start on a seasonably cool note

 August had its fair share of cool and warm stretches, including a few days in the 90s just last week. But when all was said and done, we finished with an equal number of days with above average and below average highs. Rainfall was a little lacking, as we saw only 2.22", nearly 2" below average for August.

We will continue to stay dry tonight despite a passing cold front around 1-2AM. This will bring a small uptick in cloud cover, but more importantly, flip our winds around to come from the North into tomorrow morning. Temperatures will drop into the low 60s and upper 50s under mostly clear skies tonight.

The Northerly winds tonight will keep us underneath a cool breeze tomorrow. Along with cooler air aloft and surface high pressure, this will aid in keeping temperatures in the mid-70s Sunday and Monday, slightly below the average high of 80°. Overnight lows will be even cooler, down near 50°, well below the average low of 59°.

Sunday night's cold front will also bring more dry and cool weather for the next few days. Moisture remains very low through mid-week, keeping rain chances few and far between. Zero rainfall expected through at least Wednesday.

Our next chances for rain don't swing in until Thursday. The influence of dry high pressure keeps us cool through Tuesday, but gradually temperatures will start to climb as the high pressure pulls away. Scattered showers and an isolated storm may be possible Thursday into Friday along our next cold front, but things cool off again for next weekend, back into the low 70s for highs.

Temperatures set to cool through Labor Day weekend and beyond

 After starting the week with 90-degree temperatures and near record setting conditions we look to begin to slide right back in to below average temperatures for the season once again. Multiple pattern changes have now occurred just in the past few weeks with temperatures ranging nearly 50 degrees between observed highs and observed lows through that time. But expect us to once again get back into cooler and below average temperatures as we enter September.

Before diving into the next week, we can take a look at how much our high temperatures have ranged nearly the past two weeks. With multiple instances of high pressure occurring during this time the placement and out position of the high pressure really determines temperatures for that period. In the middle of August high pressure was centered to our south and west trapping us in cool temperatures but as it moved east and positioned over us is when we see temperatures dramatically spike. However, as that system has now moved off, we once again begin to slide into weak high pressure with northerly flow being dominant helping cool temperatures be funneled into the region.

 Comparing last week's temperatures to the forecasted temperatures this week we can clearly see just how fast this pattern has changed. The previous system of high pressure offered plenty of southerly warm flow really driving temperatures up almost near 100 degrees on Tuesday. As previously mentioned, northerly flow around the current high pressure will really keep us cool but this cool weather will be a relief to many as Tuesday alone will see a 22 degree decrease in temperature since last Tuesday!

Expect this cooler weather to stick around at least until next weekend where forecasted temperatures are expected to stay in the upper 70's to low 80's. This pattern moves us into September which is the meteorological start to fall. Some nightly temperatures will really bring the fall feel as some nightly temperatures will drop to 50 degrees and possibly lower in some locations. Warmer temperatures are slowly starting to fade away as we approach fall so, take advantage of this comfortable pattern while it lasts!

Humidity drops in time for the holiday weekend

 Cloud cover has been a little pesky Friday afternoon, limiting many spots from warming into the 80s. Rockford's high reached 79° as of 4PM. Through the evening, our passing cold front will begin to clear out thick cloud cover, presenting us with mostly clear skies overnight. Overnight lows will drop into the upper 50s, reaching a low of 58 in Rockford. Decreasing cloud cover will allow for great weather for our opening week of high school football!

This cold front will clear much of the low-level moisture out of the region, with dew point temperatures falling to the 50s through Saturday. A secondary front Sunday morning will only aid in the cool and comfortable trend, reinforcing a fall-like air mass for the holiday weekend.

The forecast for the weekend looks sunny and seasonably cool after Saturday, with high temperatures dropping day after day from the low 80s Saturday to the mid-70s Sunday and Monday. Perfect weather for any outdoor plans, as rain chances remain far away.

Afternoon highs will be seasonably cool, but so will overnight lows. Low 50s will be the trend through the early week for overnights. Great weather for opening the windows and getting some free A/C! Temperatures will then slowly begin to climb through the middle to end of next week, with highs reaching near 80° again by Wednesday and Thursday. Rain looks to be limited through the week, with our next chances not until the end of the week.

Friday morning weather update

A weakening line of showers and non-severe storms associated with our next cold front is bringing much needed rainfall to the Stateline. As of 4:30AM, rainfall totals range from .67" in Rockford to .1.16" up in Monroe to 1.57" in Savanna. 

If you plan to step out the door early, make sure to have the umbrella with you. Once this morning's rain clears out, coverage will turn spotty and light in nature. Cloud cover however is expected to hang tight for most if not all of the daylight hours.

The downward trend in afternoon temperatures continue with most peaking in the low 80s. Skies are to gradually clear around or just after sunset, which is great news for those heading to week 1 of high school football. This will also make for a cooler morning to kick off the upcoming holiday weekend as most look to in and around the 60° mark. 

High pressure settling in will result in plenty of sun from Saturday through Monday. The only exception, a few clouds early Sunday as a secondary cold front passes through the region. With this cold front, we're not expecting any precipitation. However, behind this frontal passage will be our next taste of fall which will help drop temperatures into Labor Day. Highs Saturday will be in the low 80s,  cooling into the 70s for both Sunday and Monday.

Fall-like stretch starting Labor Day weekend

 A period of strong storms may be possible late into the evening tonight, mainly after 2AM. A few storms may pose a risk for severe weather, with isolated pockets of damaging winds posing the main risk.

We may see a few storms linger into Friday morning, but generally dry conditions expected most of the afternoon as temperatures remain warm with highs in the low 80s. A few very spotty showers may return for the afternoon along the trailing cold front, but most will remain dry through much of the daytime hours.

 

Following that cold front, a secondary front will push in a much cooler air mass for the weekend, making things feel much more like fall into early next week. This will come as surface high pressure takes over, allowing for abundant sunshine, dry conditions, and seasonably cool temperatures. A very pleasant stretch of weather heading into the unofficial end to summer!

Prior to the secondary front, things will remain seasonably warm but dry Saturday, with gradually dropping temperatures throughout the holiday weekend. Afternoon highs will be down in the upper 70s Sunday and mid-70s by Monday! Dry conditions continue much of next week as high pressure settles in, but temperatures will gradually warm back near 80° by Thursday.

Thursday afternoon weather update

 

Cloud cover Thursday was a little slow to depart for some, leaving temperatures across northern Illinois and southern Wisconsin in the mid-70s through early afternoon. But now that the clouds are beginning to clear temperatures have warmed area-wide into the low to mid 80s. Dew points nearing 70 degrees, however, have pushed the heat index into the low 90s.

Dry conditions will last through most of Thursday evening as severe storms continue across the Upper Midwest. These storms are forming ahead of a cold front that'll slide through the Stateline Friday morning.

The greatest risk for severe weather remains focused across the Midwest through Thursday evening. As both the cold front and line of storms move east it is likely we'll see a weakening trend, especially as the storms near the Mississippi River. However, the leading edge of the storms may still be capable of gusty winds after Midnight, which is why there is a 'marginal' risk for isolated severe storms west of I-39.

Rain and thunder chances will increase after 1am, moving across the region through 6am Friday. As the eastward progression of the front slows Friday a few showers and isolated thunderstorms may be possible, especially southeast of Rockford.

Skies will then clear through Friday night as high pressure moves in for the weekend. Humidity will also lower significantly making it feel much more comfortable through the Labor Day holiday.   

Storms possible early Friday, fall-like cooldown to follow

Improvements were felt Wednesday as the air wasn't as hot and definitely wasn't as humid. This downward trend in both departments is expected to continue, making for a refreshing holiday weekend. 

Thursday starts off with areas of patchy fog, which may slow your morning travels down a bit. Shortly after fog issues dissipate, clouds will give way to more sunshine. This will allow afternoon highs to peak in the upper 80s. With dew point temperatures sitting near the 70° mark, expect heat indices to peak in the low 90s. Still hot, though not  as dangerous as what was felt Monday and Tuesday.

Overnight, our attention then turns to a line of showers and storms that spark up along a cold front in Minnesota and Iowa. Forecast models bring this activity southeastward, entering N. Illinois and S. Wisconsin around 1-2AM. While these will be weakening on approach, they still could pack a punch by producing gusty winds and heavy rainfall. Coverage is then expected to decrease as we approach the mid-morning hours, leaving the rest of our Friday dry under a mostly cloudy sky. Afternoon highs will end up slightly cooler in the low 80s.

Skies will clear out behind the frontal passage, setting up a gorgeous holiday weekend. Plenty of sunshine is expected as high pressure slides in behind the departing cold front. Some clouds may be possible early in the day Sunday as a secondary cold front slides through. However, the bigger headline with Sunday's frontal passage is the cool-down that follows, leaving us very fall-like for Labor Day and for the first few days of September.

Cooler trend heading into Labor Day weekend

 It has been a much cooler day compared to Monday and Tuesday across the Stateline, but the humidity remains high with dew points in the 70s. This will remain the case as a pair of cold fronts pass through, bringing a cooler holiday weekend.

The first of which will slide through Thursday night bringing a chance for some storms along the leading edge of the cold front. A line of gusty storms may form well Northwest of us, with an isolated chance for some strong to severe storms, mainly North and West of Rockford where a Level 1/5 Marginal Risk from the SPC lies.

 

By Friday morning, most of the storm activity will have been shifted South and East of Rockford, but a few showers and isolated storm may linger into mid-day. The severe threat also shifts well Southeast, mainly focused on Central Illinois into Indiana where another Level 1/5 Marginal risk is set up.

 

Heading into the holiday weekend, that cold front will begin to drop our temperatures down, with afternoon highs in the low 80s Saturday and then 70s Sunday and Monday. Meanwhile, the entire holiday weekend looks dry as well, with increasingly comfortable air settling in.

Regarding any holiday travel, Thursday night into Friday looks to be the main window for any showers and storms locally, with that threat shifting well South and East by Saturday and Sunday. A much cooler and drier air mass will then settle in by Monday and Tuesday.

   

Wednesday afternoon weather update

 

Temperatures are quite a bit 'cooler' Wednesday afternoon following the passage of a cold front Tuesday evening. That front brought scattered thunderstorms to the region overnight, with skies remaining partly sunny through much of Wednesday afternoon.

Temperatures area wide have warmed into the low to mid 80s, but with dew points still in the upper 60s and low 70s the muggy feeling will continue through the evening - although not nearly as humid as the last few days.

A few showers have developed to the north in Wisconsin along a convergence boundary, where winds are coming together. A very small chance for an isolated shower will be possible across southern Wisconsin and far northern Illinois through the evening but most will remain dry during that time.

As skies turn partly cloudy Wednesday night temperatures will fall into the mid-60s. With the recent rain this may allow some areas of fog to develop. Skies will turn partly cloudy Thursday afternoon as highs warm back into the upper 80s. An approaching cold front from the northwest will move closer to the Stateline Thursday night giving us our next chance for showers and thunderstorms through the night.

Severe weather will be likely to the northwest Thursday afternoon, with a small chance for some gusty winds after dark locally. The front passes Friday morning which will take most of the rain chance with it by the afternoon. Temperatures will be in the mid-80s Friday afternoon.

Not as excessively hot today, though humid conditions linger

Last night's widespread rainfall was welcomed with open arms considering we haven't seen anything over 0.10" since August 16th. Most across northern Illinois wound up with .15" to .25", with higher rainfall totals observed to our south and east. 

Big day ahead for RPS 205 students as the new school year gets underway. Thankfully, conditions will be fairly quiet throughout the day, though an isolated passing shower or thunderstorm cannot be ruled out. Despite a cold front coming through overnight, it will still be a very warm and muggy, though not to the extent of Tuesday. Afternoon highs should peak in the mid to upper 80s, with heat indices ending up near the 90° mark.

Thursday will be very similar to Wednesday, with afternoon highs reaching the upper 80s under mainly dry conditions. A stronger cold front will enter the equation Thursday night into Friday morning, bringing with it a much more organized chance for widespread clusters of showers and storms. While severe weather potential is low, heavy rainfall and sporadic wind gusts will be possible. 

 

Temperatures following this frontal passage will fall back into the low 80s for Friday and Saturday. A third cold front is shown sliding through Sunday, allowing a stronger push of cooler air to occur into the Great Lakes. Expect highs early next week to land in the low to mid 70s, which is a whopping 18° to 22° cooler than highs the last two days. Along with the cooler temperatures will come generally tranquil conditions as multiple high pressure systems slide into the Midwest and Great Lakes.

Tuesday afternoon weather update

2pm Update: The severe thunderstorm watch has been canceled for Winnebago, Rock, and Walworth counties. 

 A Severe Thunderstorm Watch was issued for Rock and Walworth counties in southern Wisconsin as well as for Winnebago, Boone, and McHenry counties in northern Illinois until 4pm.

An outflow boundary that formed from storms in Wisconsin earlier in the morning continues to move across southeast Wisconsin and northeast Illinois, producing isolated storms as it does. Cumulus clouds have started to develop, and grow, in some locations allowing storms to slowly begin to develop. One such storm is just north of Poplar Grove in Boone County (Illinois).

The short duration of the watch means that the risk for widespread severe weather through the afternoon is low, but it's there. And as the outflow boundary moves into an extremely unstable environment - given temperatures in the 90s and dew points in the upper 70s and low 80s - quickly developing storms are possible. However, the warmer temperatures have also put a cap - or lid - on the atmosphere which has made it somewhat difficult for more widespread storm activity to form along the boundary.

So, for the remainder of the afternoon isolated storms will be possible with a low-end risk that a storm could become strong to severe. If we do see severe storms form, damaging winds and large hail would be the primary concerns, along with heavy rainfall. Additional thunderstorms remain possible later this evening ahead of a cold front, with the risk still in place for scattered severe storms through Midnight.

Excessive heat warning in place for all of northern Illinois

For the third straight day, temperatures and heat indices increase at the Rockford Airport. This left high temperatures in the lower to mid 90s, and heat index values as high as 108°. 

 

 

 

Unfortunately, things look to remain hot and humid as we jump into Tuesday. Thus, the National Weather Service converted yesterday's excessive heat watch to an excessive heat warning. This is for the entire area and will be in place from 12-10PM. 

Expect high temperatures in the mid 90, with heat indices registering as high as 115°. Again, steps to ensure safety from the heat include taking frequent breaks in the shade or A/C, wearing light colored clothing, and stay hydrated. Pet and child safety needs to be a high priority as well. Make sure they are not unattended outside or left inside of a vehicle. Now, we'll have monitor any outflow boundaries produced by nearby storm complexes.

Two are shown sliding into northern Illinois, one around sunrise and then another sometime during the afternoon. The boundary slated for this afternoon may not only limit today's potential to excessive warm up, but it also may contribute to a late day chance for storms. So will the cold front that's slated to pass through tonight into early Wednesday morning. 

For that, the Storm Prediction Center has most of the region under a level 2 Slight Risk for severe weather, mainly for strong winds and large hail. Forecast models then show tonight's cold front stalling to our south somewhere near I-80. This will be the general area where we can expect further storm development Wednesday afternoon and evening. Highs won't be as warm, though humid conditions will stay put.  
 

High humidity builds Monday afternoon

 A Heat Advisory remains in place until 8pm Monday for Winnebago, Boone, Ogle, Lee, DeKalb, and McHenry counties, while an Excessive Heat Warning remains in place for Stephenson, Jo Daviess, Carroll, Whiteside, Green, Rock, and Walworth counties. These alerts are in place as heat index values approach 110-115 degrees!

Little relief is expected Monday night with overnight lows only expected to fall into the mid-70s, jump starting the climb in temperatures Tuesday afternoon.

A strong ridge of high pressure centered over the Midwest Monday has kept skies cloud free, allowing temperatures to soar Monday afternoon. This ridge will hold strong through Tuesday, although storms developing to the north Monday evening may allow for an outflow boundary to sink south of the state line Tuesday morning which *could* bring afternoon high temperatures down just a bit.

However, the expectation is for the boundary to have little impact, with temperatures warming back into the mid-90s and heat index values reaching 110-115 degrees Tuesday afternoon. As a result, an Excessive Heat Warning will be in place for the entire viewing area through Tuesday evening.