Summer heat returns for the start of August

 

Following a few rain showers early Thursday morning skies were quick to turn partly cloudy for the remainder of the afternoon and evening with temperatures warming into the upper 70s and low 80s. High pressure sinking down from the northwest Thursday night will help skies clear out, allowing temperatures to drop into the mid and upper 50s. Partly cloudy skies will continue for Friday with high temperatures warming into the low 80s once again. In fact, high pressure remains the rule of thumb straight through the weekend as temperatures gradually climb through the mid and upper 80s Saturday and Sunday.

Hopefully you're able to get out and enjoy the weekend because the heat is set to return as early Monday, but temperatures are expected to rise into the 90s by next Wednesday. A warm front pulling through the region late Sunday night may produce an isolated shower or storm, but residual dry air should keep the storm chance low. The warm front passes Monday bringing temperatures into the upper 80s during the afternoon. Dew point temperatures are also forecast to increase rising back into the 60s, possibly low 70s, causing the humidity to increase as well.

Thunderstorms may be possible late Monday afternoon and evening as a cold front nears from the north/northwest. Building heat and instability, along with a little kink in the jet stream, may be just enough to produce a few gustier storms - something we may need to keep an eye on going into the weekend. High pressure moving to our north Tuesday will shift winds around to the northeast, which may drop some of the humidity during the afternoon but temperatures are still expected to warm into the mid and upper 80s.

A second warm front moving in early Wednesday will pull in quite a bit of heat as temperatures are expected to warm well into the 90s during the afternoon. As of Thursday evening, the forecast high for next Wednesday is 94 degrees. The duration of the heat will depend on the strength of the ridge aloft. It's possible that those 90 degree temperatures could continue straight into next weekend, but the ridge may weaken and sink to the south, especially if several storms form along the outer edge of the ridge helping to flatten it. Either way, temperatures rising back into the 90s next Wednesday are more than likely, with those highs likely lasting into next Thursday. 

Pair of Fronts Bring Brief Shower Chances Ahead of Dry Weekend

Historic Rainfall:

A stationary boundary draped across the southern portion of the state brought historic rainfall to areas in and around St. Louis on Tuesday. When it was all said and done, the National Weather Service came in with a 24 hour rainfall total of 9.04". 

This completely shattered the previous all-time daily record of 7.02" left behind by the Galveston hurricane remnants in August of 1915. To further blow your mind, the St. Louis area saw more rainfall in a 24 hour period than the Rockford Airport has seen since the beginning of meteorological summer (June 1st). While that boundary will keep rain chances to our south, a pair of cold front sliding in from the northwest will bring a few hit-or-miss chances ahead of the weekend. 

First Cold Front:

Guidance shows the first of two cold fronts sliding through before mid-day, bringing with it the chance for widely isolated showers. Once the front is to our south and east, conditions on the backside will slowly clear up during the afternoon, with highs peaking in the lower 80s. Expect mixed sunshine for the drive home later today with conditions remaining dry into the overnight hours.

Secondary Front:

Shortly after the midnight hour, clouds will quickly increase as a secondary boundary enters the region from the northwest. This one also having enough lift and moisture with it to produce a few isolated showers during the early stages of our Thursday. In a similar fashion to today's forecast, conditions will dry out post-frontal passage, with highs climbing into the upper 70s and lower 80s.

Dry Conditions Follow:

Sliding in behind our two midweek cold fronts is a high pressure system that will quickly bring down rain chances before the weekend. Under a mix of clouds and sunshine, highs Friday afternoon look to fall short of the 80-degree mark. 

However, this cool-down is brief as both Saturday and Sunday call for highs in the 80s. Thankfully, high humidity levels will continue to hold off. That in my opinion is fantastic news for those heading to either the Lee County of Stephenson County fairs!

Brief rain chances return midweek

 

Tuesday afternoon has been another beautiful day, comfortable too, as temperatures have warmed into the upper 70s and low 80s. A great day for the start of the Stephenson County Fair in Freeport! Skies will remain dry through the evening and most of the night as cloud cover slowly increases from the south and west.

The Stateline is sandwiched between a cold front to the north and stationary boundary to the south.

Extremely heavy rainfall fell along the stationary front, bringing record rainfall to areas in and around the St. Louis, MO region where totals added up to over a foot of rain in just 12 hours! According to the National Weather Service in St. Louis, the metro received 25% of their yearly rainfall total in just 12 hours! That's a lot of rain! Unfortunately, the heavy rain threat continues across southern portions of Missouri, Illinois, Indiana and Kentucky.

Closer to home we'll see a few showers dot the skies early Wednesday morning, with another chance for rain returning Thursday morning. No severe weather is expected but a few isolated rumbles of thunder can't be ruled out. These will be forming as a couple cold front pass through the Midwest and Great Lakes, eventually pulling down a slightly cooler air mass through the end of the week.

Rainfall amounts are not expected to be much, only a tenth of an inch or two across the region, although a few locally higher amounts could be possible. After that, high pressure builds in for the end of the week as temperatures remain in the low 80s through the start of the weekend.

Remaining Comfortable, Few T-Storms Possible Early Wednesday

Remaining Comfortable:

Yesterday was nothing short of spectacular as the drop in temperature and humidity were definitely felt across the Stateline. Highs peaked in the mid to upper 70s, making it just the fourth day this month in which we've failed to reach the 80° mark. Much like Monday, the rest of the work week features generally seasonable temperatures and tranquil conditions. The one hiccup so to speak comes in the form of a cold front late tonight into Wednesday. 

Another dry and comfortable start greets us out the door this morning, with temperatures sitting on either side of the 60-degree mark. In a similar fashion to Monday, most of the daylight hours will be spent under a mixture of clouds and sun. 

With a more southerly to southwesterly tilt in our winds this afternoon, the mercury rises back into the lower 80s. Despite the climb in air temperatures, the humidity remains comfortable.  

Wednesday's Rain:

Remember that cold front I mentioned earlier in this post? By this evening, that frontal boundary will be approaching the Stateline area from the northwest. As it does, a round of showers and thunderstorms will spark along it, tracking to the southeast with time. Over the last 12-24 hours, forecast models have really backed off on our rain chances, with the heaviest rainfall occurring downstate. Still, the chance for a few scattered showers and thunderstorms will be in play into the mid-day hours, with drying taking place during the afternoon. Highs will once again top out in the lower 80s. 

Cooling Back Down:

Behind Wednesday's frontal passage, a slightly stronger round of cold-air convection takes place across the western Great Lakes. 

This will bring our high temperatures down by a few degrees for the remainder of the work week, with the likelihood of upper 70s for Friday afternoon. Along with the cooler weather comes a stretch filled with sunshine as an area of high pressure takes over. In fact, our next rain opportunity doesn't look to occur until the beginning of next week. So whatever we get out of tonight's chances will more than likely be the last chance for the month of July! 

Humidity Levels Drop, Next Rain Chance Arrives Midweek

Humidity Drops:

The big weather story as we jump into the new work week is going to be the drop in humidity that follows a pair of cold fronts. The first frontal boundary passed through Sunday morning, which made it feel A LOT more comfortable as we inched closer towards sunset.  

Winds overnight remained light out of the west and northwest, bringing dew points values down into the upper 50s this morning. In other words, we can expect a VERY refreshing start to the day. 

A good amount of sunshine is expected early, with a gradual increase in cloud cover likely during the afternoon. Jumping back to today's north-northwesterly for a brief moment, this will also bring our high temperatures down by a few degrees, with some not making it out of the 70s. 

Next Cold Front:

As high pressure slides eastward into the Great Lakes, winds will take a turn and be more out of the south for Tuesday. This will likely bring our temperatures back into the lower 80s, with moisture levels increasing slightly as we get towards the evening commute. Along with a few more late-day clouds, a few isolated sprinkles or light showers cannot be ruled out. With that being said, the higher potential for rain and even thunderstorms arrives overnight Tuesday into Wednesday with our next front.

Remaining Comfortable:

Whatever falls during this time will add onto what has been a remarkable July rainfall-wise. As of this morning, the Rockford International Airport has observed 5.23" of rain, which lands just over 2 1/4" July's average to date.

On the flip side, this will be our only big chance for rain before we jump into the month of August. A second area of high pressure slides in behind Wednesday's frontal passage, keeping sunshine in the forecast into the weekend. Highs fall back to the 80-degree mark Thursday, with the potential for another 70-degree day on Friday. This week's cooler, less humid weather pattern will bring a big-time opportunity to give the A/C a much-needed break! 

Less humid days expected for the last week of July

 

A steady drop in humidity can be expected Sunday evening following the passage of a cold front that brought numerous severe thunderstorms both Friday night/Saturday morning and Saturday night/Sunday morning.

Sunday night will be much more quiet as high pressure slowly moves into the region. While we've been able to see some clearing of the cloud cover from earlier Sunday afternoon, a slow increase in the clouds from the west can be expected. Temperatures Sunday night will fall on either side of 60 degrees.

Northwest winds will also continue to blow Sunday evening but should slowly begin to subside once the high pressure system moves closer. The northwest wind will also bring a drop in our dew point temperatures with numbers expected to settle into the 50s overnight, early Monday morning. Drier air is then set to remain in place for much of the week, although a little spike in humidity is expected Tuesday night and Wednesday as the wind changes back around to the southwest.

Dew points throughout much of Sunday were still in the upper 60s, giving the afternoon a slightly humid/muggy feel. But as the drier air moves in it should begin to feel much more comfortable not only Sunday night, but also for most of the week. Temperatures to round out the week will settle into the upper 70s and low/mid 80s - fairly seasonable for the end of July.  

Weather Quiets Down Following an Very Active Saturday

Active Saturday:

Multiple storm complexes raced across the eastern half of the United States Saturday, producing wind reports as far as the Dakotas to the Carolinas. 

As of this morning, the Storm Prediction Center has gathered 294 wind reports, 26 hail reports, and the one tornado report. While a few storms are expected to linger into the early stages of our Sunday, the passage of this morning's front will mark the beginning of a less active and cooler stretch of weather. One that looks to last well into next week! 

Simmering Down:

The weather becomes more tranquil for the latter half of our Sunday, with clouds slowly clearing out. A wind shift to the northwest will bring our highs down a few degrees from Saturday, with most peaking in the lower 80s. 

Not only that, our humidity levels will slowly improve as the afternoon progresses. Skies remain mostly clear overnight, with lows falling into the lower 60s by sunrise Monday.

Parade of Cold Front:

High pressure takes control on Monday, allowing for a sun-filled start. However, the afternoon does feature a few more clouds as an weak upper-level disturbance slides to our south. Despite the additional clouds, the daylight hours remain dry, with highs just making it into the low 80s. 

Moisture increases ahead of our next cold front, bringing the potential for a few showers late Tuesday, with chances continuing into Wednesday. Behind Wednesday's cold front, another round of cooler air will allow to temperatures cool back down, with highs possibly not making it out of the 70s Friday. Overnight lows become more comfortable as well, falling into the lower 60s starting Wednesday.

Hot & Humid Saturday, 2nd Round Arrives Late

Hot & Humid Saturday:

Once this morning's round of showers and storms comes to a close by mid-morning, a hot and humid afternoon is to follow. Highs are expected to soar into the lower 90s. Along with the uptick in heat comes an uptick in humidity, resulting in heat indices at or above 100° for some. 

For that, the National has placed Jo-Daviess, Carroll, Whiteside, and Stephenson Counties in northern Illinois, along with Green County up in southern Wisconsin under a Heat Advisory until 8PM. Heat indices in these areas could sit near or over the 100-degree mark. If you have any plans to be outside this afternoon and evening, make sure you practice heat safety. Be sure to drink plenty of water and take frequent breaks in the shade.

2nd Round Arrives Late:

It’s during the time in which the heat advisory is in effect that our atmosphere will have the opportunity to recharge. 

This is all ahead of another round of showers and thunderstorms that's slated to move in ahead of a cold front this evening. The Storm Prediction Center placed our areas along and north of highway 20 under an Enhanced Risk (level 3 of 5) for severe weather, with the rest of area being placed under a Slight Risk (level 2 of 5). This round is expected to develop across southern Minnesota/northern Iowa late this afternoon and track east-southeast towards the region.

Damaging straight-line winds will be the primary concern with this strong line, followed by localized flooding, small-sized hail, and an isolated brief tornado. Rain and storm chances from there look to continue into the early stages of our Sunday as the cold front slides through. 

A mostly cloudy sky is expected to remain into the afternoon, with gradually clearing taking place late. The shift in wind we see behind tomorrow's frontal passage will bring highs down from the lower 90s today to the mid 80s by Sunday afternoon. We'll also see a chop in humidity levels as well. Highs will continue to fall into next week, peaking in the low 80s Monday and Tuesday. In addition to that, high pressure moves in, bringing a quiet start to the work week.

Severe Thunderstorm Watch Issued

A Severe Thunderstorm Watch has been issued for Stephenson, Carroll, Whiteside, Ogle, Lee, Dekalb, Boone, McHenry, and Winnebago Counties until 10AM this morning. 

This also includes our 3 counties (Green, Rock, and Walworth) up in southern Wisconsin. Primary concerns with any severe t-storm will be gusty winds, heavy rainfall, and small-sized hail.

7:15AM UPDATE:

The National Weather Service has cancelled the Severe Thunderstorm Watch for our three counties up in southern Wisconsin. All of our northern Illinois (minus Jo-Daviess County) remain under the watch until 10 AM. 

9:15AM UPDATE

Carroll, Whiteside, and Stephenson Counties have been taken out of this morning's Severe Thunderstorm Watch. The rest of the highlighted remain under the watch until 10AM!

 

NEW Severe Thunderstorm Warning has been issued for eastern Ogle County, eastern Lee County, and all of Dekalb County until 6AM. Primary threat include 60 mph wind and hail up to quarter-size.

              *WARNING HAS EXPIRED*

NEW Severe Thunderstorm Warning for southeast Whiteside County until 6AM this morning. This storm is moving northeast at 40 mph and is warned for 60 mph winds and nickel-sized hail.

             *WARNING HAS EXPIRED*

 

 

7:50AM UPDATE

A strong thunderstorm making it's way into southwestern Ogle County and northwestern Lee County will be capable of producing winds up of 40 mph and pea-sized hail. Storm is moving east-southeast at roughly 40 mph!

9:10AM UPDATE:

NEW Severe Thunderstorm Warning in effect until 10AM for the storm northeast of Hinkley, IL. This storm is capable of producing 60 mph winds and half dollar sized hail!

          *WARNING HAS EXPIRED*

Heat Advisory issued for some Saturday afternoon

 

A HEAT ADVISORY will go into effect for Stephenson, Jo Daviess, Carroll and Whiteside counties beginning Noon Saturday following the passage of a warm front. Behind the front, temperatures are expected to climb into the low 90s, but with a rising dew point temperature (low to mid 70s) it could feel more like the 100-105 degrees.

While the high heat and humidity are likely for some Saturday, it's also possible that not everyone will experience the hot and humid conditions. Thunderstorms are expected to develop in Iowa late Friday night, moving into northern Illinois between 11pm and 2am. Some of those storms could continue into Saturday morning, slowing the progression of the warm front north. If that occurs it is possible that some areas across north-central Illinois and south-central Wisconsin don't get as hot due to leftover showers and cloud cover. This is why the advisory has not been issued for the entire region.

If the storms Saturday morning are quick to move out, along with the cloud cover, then the warm front will quickly lift north into southern Wisconsin by the afternoon. This would mean temperatures rising into the low to mid 90s, along with heat index values over 100 degrees, would be more common throughout the day. Right now the forecast high for Saturday is 91 degrees, but it is possible that some areas may be slightly cooler/less humid than that, depending on morning storms and cloud cover. 

Brief, heavy downpours with Thursday evening showers/storms

 

Temperatures Thursday afternoon warmed into the upper 80s and low 90s but the heat index temperature climbed well into the mid/upper 90s for some. In fact, Freeport had a peak heat index temperature of 100 degrees earlier in the afternoon!

The building heat and humidity ahead of an incoming cold front has produced a few widely isolated showers and thunderstorms across southern Wisconsin and northern Illinois, although the precipitation has had a hard time maintaining strength through the evening and has been quickly weakening.

That's because of the amount of dry air in the middle of the atmosphere. Water vapor imagery shows plenty of dry across Illinois and Wisconsin, as well as out through the Ohio Valley and into the Northeast, limiting the overall ability for storms to continue to grow in both coverage and strength. While most of these showers and storms remain below severe limits, there could be one or two east of Rockford that grow enough to produce a strong wind gust or two. Areas most likely to see a higher risk for strong/severe storms will be northeast Illinois and northwest Indiana. Our storm threat, locally, will come to an end after 7pm/8pm. 

Little Warmer Today, Storm/Severe Chances Best Saturday into Sunday

Staying Breezy:

The Stateline has seen no break from the wind over the past few days as peak gusts once again registered between 25 to 35 mph. 

The big difference-maker however was the shift in wind we experienced behind yesterday's cold front. Left behind was a gusty west to northwesterly wind, which helped bring down the heat and humidity for the later half of Wednesday.

Expect another breezy afternoon today. Winds this time around will be our of the west-southwest, which will bring the mercury up a few degrees. Highs for most will peak in the upper 80s, with a spot or two just touching the 90-degree mark. 

With a little lift and atmospheric energy present ahead of a sinking cold front, a widely isolated afternoon shower or thunderstorm is possible. Otherwise, much of the day remains dry under a mix of clouds and sun. Behind this evening's cold front, an area of high pressure system will keep skies clear overnight and into mid-day Friday. 

Rain Chances Increase:

Despite clouds increasing Friday afternoon, rain and thunderstorm chances hold off until late Friday evening into Friday night. Severe risk will Friday's chances are low, hence why the Storm Prediction Center continues to keep the Stateline under a Marginal Risk (level 1 of 5). Damaging straight-line winds will be the primary concern with any thunderstorm deemed severe. 

The first half of the weekend features out best precipitation chances, especially during the latter half of the day. For that, the Storm Prediction Center has placed areas along and north of Interstate 88 under a Slight Risk (level 2 of 5), with areas to our north and west placed under an enhanced risk (level 3 of 5). 

Saturday will be a hot one and somewhat more humid with highs in the lower 90s. When you factor the uptick in humidity levels, it’s possible that heat index values approaching the triple-digit mark. Chances look to continue overnight into Sunday morning as another frontal passage occurs. 

This will bring highs back down towards seasonable levels for the end of the weekend and for the start of next week. As we said yesterday, there still is time for the forecast to change. Over the next day or so, it's going to be important to stay up-to-date with the forecast so that you have the latest information.

Isolated showers/storms possible Thursday afternoon

 

Skies were mostly clear Wednesday morning but were quick to fill with cloud cover late morning and early afternoon as low pressure continued to spin across the northern Great Lakes. The combination of moisture in the atmosphere, warming temperatures and a weak upper level disturbance rippling through the jet stream were just enough to keep our skies mostly cloudy for a time, but rain free. Rain showers remained well to the north in Wisconsin.

We are beginning to see our skies clear Wednesday evening, but smoke from wildfires well north in Canada has been caught in the jet stream and currently moving into the Midwest. As a result, the sunset Wednesday evening - especially across NW IL - may look a little more hazy/cloudy. That haze may also continue into early Thursday morning.

Winds Thursday will begin to shift to the south, and then southwest, ahead of a cold front that'll pass through during the afternoon and evening. Temperatures ahead of the front will warm into the upper 80s and low 90s, but dew point temperatures should remain in the mid 60s. This will help keep the heat index temperature close to the actual air temperature. Instability will also increase ahead of the front Thursday which could help produce a widely isolated shower or storm during the mid to late afternoon. Dry air, however, will keep any storm coverage widely isolated and limited. Once the cold front passes a quick moving high pressure system will slide into the region bringing mostly dry skies during the first half of the day Friday before another round of showers and storms move in Friday night.  

Another Breezy Day, Pattern Turns More Active By the Weekend

Another Breezy Day:

Tuesday's warm southwesterly wind made for another seasonably warm afternoon as all of our local airports peaked in the mid to upper 80s. 

However, it definitely felt more like we were in the low to mid 90s as dew point temperatures sat in the low 70s. Thankfully, some relief slides in for the second half of the work week thanks to the cold front that slides through this morning. 

While much of the region will remain dry during this morning's frontal passage, an isolated shower or thunderstorm cannot be ruled out. Winds behind the cold front look to turn to the west by mid-day, then to the northwest for the afternoon hours. 

In a similar fashion to Tuesday, gusts will range from 25-30 mph. This cooler wind will help bring a slight drop in our air and dew point temperatures for the middle of the work week. Under a mix of clouds and sunshine, highs will peak in the upper 80s. As drier air continues to pile in, any cloud cover that's around during the afternoon and evening will clear out, leaving us with a mostly clear sky for tonight.

Turning Active Late:

More of the same can be expected for Thursday, minus the gusty wind. However, winds will be tilting more to the west-southwest, bringing temps up back near the 90-degree mark. 

By week's end, the ridge of high pressure that's been dominating the western U.S flattens a bit, allowing for some more heat to filter into the Great Lakes. High temperatures remain in the upper 80s and low 80s into the weekend, with our best opportunity for some heavy rainfall coming in with a stationary boundary late Saturday.

Guidance keeps rain chances into Sunday as this frontal boundary sinks southward as a cold front. The closer we get to the weekend, the more we'll know about timing and accumulations. 

Now, like today's frontal passage, winds behind the front will turn back to the northwest, bringing temperatures down a bit as we head into the beginning of next week. Highs fall to the lower 80s for both Monday and Tuesday, with overnight lows falling into the lower 60s.

Brief drop in humidity mid-week

 

Temperatures Tuesday afternoon fell just shy of the 90 degree mark, but it felt more like the low to mid 90s as dew point temperatures climbed into the low 70s. The rise in moisture was the result of a gusty southwest wind for much of the afternoon; those wind speeds should slowly begin to subside through the late evening.

We had a few more clouds Tuesday afternoon as a weakening cluster of showers and thunderstorms

moved across central Wisconsin. The majority of Tuesday evening is expected to remain dry under a partly cloudy sky. Breezy southwest winds will hold temperatures in the 80s through much of the evening, only dropping into the low 70s by Wednesday morning.

A cold front passing through southern Wisconsin and northern Illinois late Tuesday night will bring with it just an isolated chance for a shower/storm, but most are likely to remain dry. Winds shifting around to the west, and then northwest, Wednesday afternoon will help bring dew point temperatures down into the mid 60s. While still humid, it won't feel quite as muggy as it did Tuesday afternoon. Dew point temperatures are expected to remain in the mid 60s for Thursday afternoon.