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(7:30PM - 8/26/20) A heat wave continues to to affect the state and region, and will continue through Friday. Hot temperatures will continue to be expected during this time, with the potential for some records to fall.
Summary.... A strong ridge that had been in place across the Inter-Mountain West and Plains has shifted eastward, on into the Central US. This ridge will continue to be in place through the end of this week, bringing hot temperatures to much of the state and region. High temperatures will be widespread in the low to upper 90's across the state through Friday, with some areas in Northern and Central Illinois possibly nearing 100 a few of the days. Daily record high temperatures will be in jeopardy for some areas each day as well. 
Forecast For Next Two Days...
Thursday, August 27th Forecast... High temperatures will range from the low to mid 90's across Northern and Central Illinois, to the upper 80's to mid 90's across Southern Illinois. Heat index values will be moderate, in the low to upper 90's. Low temperatures in the upper 60's to upper 70's will be common across the state. Friday, August 28th Forecast... High temperatures will range from the upper 80's to low 90's across much of the state, the exception being Southern Illinois where the remnants of Hurricane Laura will keep temperatures a bit cooler. Heat index values will be moderate, in the low to upper 90's across much of the state, once again the exception being Southern Illinois. Low temperatures in the mid 60's to mid 70's will be common across the state.
Recap Summary...
Saturday, August 22nd Recap... High temperatures topped out in the upper 80's to low 90's across Northern and Central Illinois, to the mid to upper 80's across Southern Illinois. Heat index values were low, and not much higher than the actual air temperatures. Low temperatures in the low 60's to low 70's were common across the state. Sunday, August 23rd Recap... High temperatures topped out in the upper 80's to mid 90's across the state. Heat index values were low, and not much higher than the actual air temperatures. Low temperatures in the low 60's to low 70's were common across the state. A few isolated showers and t'storm occurred across portions of Northern and Central Illinois, which tempered the heat a bit for some areas. Monday, August 24th Recap... High temperatures topped out in the mid to upper 90's across Northern and Central Illinois, to the upper 80's to mid 90's across Southern Illinois. Heat index values were moderate, generally in the low 90's to low 100's. Low temperatures in the mid 60's to low 70's were common across the state. Tuesday, August 25th Recap... High temperatures topped out in the low to upper 90's across Northern and Central Illinois, to the upper 80's to mid 90's across Southern Illinois. A back-door front kept portions of Northeast Illinois a bit cooler. Heat index values were moderate, in the low 90's to low 100's. Low temperatures in the mid 60's to mid 70's were common across the state. Wednesday, August 26th Recap... High temperatures topped out in the low to mid 90's across Northern and Central Illinois, to the upper 80's to mid 90's across Southern Illinois. Heat index were moderate, in the low to upper 90's. Low temperatures in the upper 60's to mid 70's were common across the state.
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(7:30PM - 8/25/20) A heat wave continues to to affect the state and region, and will continue through Friday. Hot temperatures will to be expected during this time, with the potential for some records to fall.
Summary.... A strong ridge that had been in place across the Inter-Mountain West and Plains has shifted eastward, on into the Central US. This ridge will continue to be in place much of this week, bringing hot temperatures to much of the state and region. High temperatures will be widespread in the low to upper 90's across the state through Friday, with some areas in Northern and Central Illinois possibly nearing 100 a few of the days. Daily record high temperatures will be in jeopardy for some areas each day as well.
Forecast For Next Two Days...
Wednesday, August 26th Forecast... High temperatures will range from the mid to upper 90's across Northern and Central Illinois, to the upper 80's to mid 90's across Southern Illinois. Heat index values will be moderate, in the low 90's to low 100's. Low temperatures in the upper 60's to upper 70's will be common across the state. Wednesday, August 26th Forecast... High temperatures will range from the mid to upper 90's across Northern and Central Illinois, to the upper 80's to mid 90's across Southern Illinois. Heat index values will be moderate, in the low 90's to low 100's. Low temperatures in the upper 60's to upper 70's will be common across the state.
Recap Summary...
Saturday, August 22nd Recap... High temperatures topped out in the upper 80's to low 90's across Northern and Central Illinois, to the mid to upper 80's across Southern Illinois. Heat index values were low, and not much higher than the actual air temperatures. Low temperatures in the low 60's to low 70's were common across the state. Sunday, August 23rd Recap... High temperatures topped out in the upper 80's to mid 90's across the state. Heat index values were low, and not much higher than the actual air temperatures. Low temperatures in the low 60's to low 70's were common across the state. A few isolated showers and t'storm occurred across portions of Northern and Central Illinois, which tempered the heat a bit for some areas. Monday, August 24th Recap... High temperatures topped out in the mid to upper 90's across Northern and Central Illinois, to the upper 80's to mid 90's across Southern Illinois. Heat index values were moderate, generally in the low 90's to low 100's. Low temperatures in the mid 60's to low 70's were common across the state. Tuesday, August 25th Recap... High temperatures topped out in the low to upper 90's across Northern and Central Illinois, to the upper 80's to mid 90's across Southern Illinois. A back-door front kept portions of Northeast Illinois a bit cooler. Heat index values were moderate, in the low 90's to low 100's. Low temperatures in the mid 60's to mid 70's were common across the state.
(11:30PM - 8/24/20) A heat wave continues to settle in across the region, and will continue through late this week. Hot temperatures will be likely during this time, with the potential for some records to fall.
Summary.... A strong ridge that had been in place across the Inter-Mountain West and Plains has push eastward, on into the Central US. This ridge will be in place much of this week, bringing hot temperatures to much of the state and region. High temperatures will be widespread in the low to upper 90's across the state through Thursday, with some areas in Northern and Central Illinois possibly nearing 100 a few of the days. Daily record high temperatures will be in jeopardy for some areas each day as well. 
Forecast For Next Two Days...
Tuesday, August 25th Forecast... High temperatures will range from the mid to upper 90's across Northern and Central Illinois, to the upper 80's to mid 90's across Southern Illinois. A back-door front will likely keep portions of Northeast Illinois a bit cooler. Heat index values will be moderate, in the low 90's to low 100's. Low temperatures in the mid 60's to mid 70's will be common across the state. Wednesday, August 26th Forecast... High temperatures will range from the mid to upper 90's across Northern and Central Illinois, to the upper 80's to mid 90's across Southern Illinois. Heat index values will be moderate, in the low 90's to low 100's. Low temperatures in the mid 60's to mid 70's will be common across the state.
Recap Summary...
Saturday, August 22nd Recap... High temperatures topped out in the upper 80's to low 90's across Northern and Central Illinois, to the mid to upper 80's across Southern Illinois. Heat index values were low, and not much higher than the actual air temperatures. Low temperatures in the low 60's to low 70's were common across the state. Sunday, August 23rd Recap... High temperatures topped out in the upper 80's to mid 90's across the state. Heat index values were low, and not much higher than the actual air temperatures. Low temperatures in the low 60's to low 70's were common across the state. A few isolated showers and t'storm occurred across portions of Northern and Central Illinois, which tempered the heat a bit for some areas. Monday, August 24th Recap... High temperatures topped out in the mid to upper 90's across Northern and Central Illinois, to the upper 80's to mid 90's across Southern Illinois. Heat index values were moderate, generally in the low 90's to low 100's. Low temperatures in the mid 60's to low 70's were common across the state.
(8:30PM - 8/23/20) A heat wave is expected to significantly impact the region and state, through late this week. Hot temperatures will be likely during this time, with the potential for some records to fall.
Summary.... A strong ridge that had been in place across the Inter-Mountain West and Plains is beginning to slide eastward, on into the Central US. This ridge will be in place much of this week, bringing hot temperatures to much of the state and region. High temperatures will be widespread in the low to upper 90's across the state Monday through Thursday, with some areas in Northern and Central Illinois possibly nearing 100 a few of the days. Daily record high temperatures will be in jeopardy for some areas each day as well. The good news is humidity and heat index values during this period of heat should remain and at low to moderate levels, as deep tropical moisture will not be in place.
Forecast For Next Two Days...
Monday, August 24th Forecast... High temperatures will range from the mid to upper 90's across Northern and Central Illinois, to the upper 80's to mid 90's across Southern Illinois. Heat index values will be moderate, and not too much higher than the actual air temperatures. Low temperatures in the mid 60's to low 70's will be common across the state. Tuesday, August 25th Forecast... High temperatures will range from the mid to upper 90's across Northern and Central Illinois, to the upper 80's to mid 90's across Southern Illinois. A back-door front could keep portions of Northeast Illinois a bit cooler. Heat index values will be moderate, and not too much higher than the actual air temperatures. Low temperatures in the mid 60's to mid 70's will be common across the state.
Recap Summary...
Saturday, August 22nd Recap... High temperatures topped out in the upper 80's to low 90's across Northern and Central Illinois, to the mid to upper 80's across Southern Illinois. Heat index values were low, and not much higher than the actual air temperatures. Low temperatures in the low 60's to low 70's were common across the state. Sunday, August 23rd Recap... High temperatures topped out in the upper 80's to mid 90's across the state. Heat index values were low, and not much higher than the actual air temperatures. Low temperatures in the low 60's to low 70's were common across the state. A few isolated showers and t'storm occurred across portions of Northern and Central Illinois, which tempered the heat a bit for some areas.
(8:30PM - 8/22/20) A heat wave is expected to impact the region, this weekend into late next week. Hot temperatures will be likely during this time.
Summary.... A strong ridge has been in place across the Inter-Mountain West and Plains over the past week or so, which has brought very hot temperatures to these areas...including a record 130° temperature in Death Valley a few days ago. This ridge will slowly extend eastward this weekend, before fully shifting eastward into the Central US for next week. Temperatures will slowly increase each of the next few days, with high temperatures in the upper 80's to low 90's being common during the weekend across the state. For early to mid next week the hottest temperatures of this stretch will be likely, potentially widespread in the low to upper 90's across the state, as the heart of the ridge moves into the Central US. The good news is humidity and heat index values during this period of heat should remain and at low to moderate levels, as deep tropical moisture will not be in place. 
Forecast For Next Two Days...
Sunday, August 23rd Forecast... High temperatures will range from the upper 80's to low 90's across the state. Heat index values will be low, and not much higher than the actual air temperatures. Low temperatures in the low 60's to low 70's will be common across the state. A few isolated showers and t'storm will be possible across Northern Illinois, which could keep high temps a bit lower in some areas. Monday, August 24th Forecast... High temperatures will range from the low to mid 90's across the state. Heat index values will be low, and not much higher than the actual air temperatures. Low temperatures in the mid 60's to low 70's will be common across the state.
Recap Summary...
Saturday, August 22nd Recap... High temperatures topped out in the upper 80's to low 90's across Northern and Central Illinois, to the mid to upper 80's across Southern Illinois. Heat index values were low, and not much higher than the actual air temperatures. Low temperatures in the low 60's to low 70's were common across the state.
(8:30PM - 8/21/20) A heat wave is expected to impact the region, this weekend into late next week. Hot temperatures will be likely during this time.
Summary.... A strong ridge has been in place across the Inter-Mountain West and Plains over the past week or so, which has brought very hot temperatures to these areas...including a record 130° temperature in Death Valley a few days ago. This ridge will slowly extend eastward this weekend, before fully shifting eastward into the Central US for next week. Temperatures will slowly increase each of the next few days, with high temperatures in the upper 80's to low 90's being common during the weekend across the state. For early to mid next week the hottest temperatures of this stretch will be likely, potentially widespread in the low to upper 90's across the state, as the heart of the ridge moves into the Central US. The good news is humidity and heat index values during this period of heat should remain and at low to moderate levels, as deep tropical moisture will not be in place.
Forecast For Next Two Days...
Saturday, August 22nd Forecast... High temperatures will range from the upper 80's to low 90's across Northern and Central Illinois, to the mid to upper 80's across Southern Illinois. Heat index will be low, and not much higher than the actual air temperatures. Low temperatures in the low 60's to low 70's will be common across the state. Sunday, August 23rd Forecast... High temperatures will range from the upper 80's to mid 90's across Northern and Central Illinois, to the upper 80's to low 90's across Southern Illinois. Heat index will be low, and not much higher than the actual air temperatures. Low temperatures in the low 60's to low 70's will be common across the state. 
(7:15PM - 8/20/20) The potential continues to increase for a period of hot temperatures across the state and region, this weekend through mid-late next week.
Summary... A strong ridge has been in place across the Inter-Mountain West and Plains over the past week or so, which has brought very hot temperatures to these areas...including a record 130° temperature in Death Valley a few days ago. This ridge will slowly extend eastward the end of this week and into this weekend, before fully shifting eastward into the Central US for next week. Temperatures will slowly increase each of the next few days, the end of this week and this weekend, with high temperatures in the upper 80's to low 90's becoming more common during the weekend. For early to mid next week the hottest temperatures of this stretch will be likely, potentially widespread in the low to upper 90's across the state, as the heart of the ridge moves into the Central US. The good news is humidity and heat index values during this period of heat should remain and at low to moderate levels, as deep tropical moisture will not be in place. 
(2:00PM - 8/16/20) An in depth recap on the significant severe t'storm event that occurred across the region on Monday, August 10th. This event featured a derecho that moved across Illinois, as well as other states in the region, bringing widespread, significant, and destructive damaging winds.
Forecast Summary... This event was not very well forecasted as little as 12-18 hours out. As of Sunday evening, 99% of model guidance did not have even near a scenario as to what actually played out. Most guidance supported the idea that overnight severe t'storm activity ongoing across portions of the Midwest would continue deep into Sunday night. Some of this activity would have the potential to affect Monday's setup for some areas, while other areas would have a better threat, with a disturbance moving through the region supporting the overall idea for a severe t'storm threat. Overall, a general minimal to limited (level 1 to 2) worthy threat was likely to be expected for Monday, as of Sunday evening. Our forecast from 9PM Sunday evening only featured a minimal (level 1) severe t'storm threat for the state and surrounding areas, with a mention that it was likely an upgrade to a limited (level 2) severe t'storm threat would be needed for some areas, pending how Sunday night activity progressed by Monday morning. With that said, there was one...single...sole outlier model that showed a significant severe t'storm threat across portions of the state and region for Monday, and showed a potential derecho affecting the region. That model was the HRRR (High Resolution Rapid Refresh model). The HRRR is a short term model, which can be useful at times, but will also spit out far left field/wacky solutions many times. So Sunday evening when it was showing that significant scenario for Monday, with no support from any other model guidance and previous history in these situations suggesting not to jump onboard with it, no thought was given to it by us or pretty much anyone else. However, as Sunday night progressed into the wee hours of the morning, and the evolution of the weather pattern across the region was a carbon copy of the the HRRR model was showing and the environment in place was very supportive of the scenario it had been showing. At that time, attention started to rapidly grow and the likelihood for an upgrade in severe t'storm probabilities for our morning update was likely. By early Monday morning before 6AM, a complex of severe t'storms had taken shape along the South Dakota/Nebraska border,with everything having gone exactly as shown up until that point by the HRRR model. By this time other model guidance had started to jump onboard as well, in addition to the continued very supportive environment in place across the region. We issued a quick forecast update blurb during the 6AM hour Monday morning, hi-lighting the need for a significant increase in severe t'storm probabilities across portions of the state, with the increasing potential for a derecho to impact portions of the state. At 11:30AM Monday morning with issued our full morning update, with an upgrade to upwards of major (level 5) severe t'storm probabilities across Northern Illinois, which is the highest severe t'storm risk on our scale. We also drove home the point on how significant the potential was for widespread, significant and destructive damaging winds across portions of the state. This high level of severe t'storm risk and significant wording was much needed in this scenario. The short term forecast upgrade to upwards of major (level 5) severe t'storm risk verified very well across Northern Illinois. Much of Central and Southern Illinois also saw a large jump in severe t'storm probabilities between the Sunday evening and Monday morning forecast, which also verified well. 
Environment Summary...
A very favorable environment for severe t'storms was in place across the region from very late Sunday night/very early Monday morning on into Monday evening, one in which has been seen in other derecho events. A large reservoir of high instability (3000-6500J/KG), deep moisture (70°+ dew points and 1.50"+ PWATS), high lapse rates (8-9.5C ML and 6-7.5C LL) and increasing shear (40-50KT+) was in place. This type of environment is generally very favorable for severe t'storms, and is also an environment that has been seen during other derecho events over the years in the region. A trigger, the main forcing mechanism for the development of activity, was a strong wave/disturbance pushing east-southeast out of Southern Canada and the Northern Rockies, down into the Northern Plans and Midwest. 
Event Summary...
The derecho moved across portions of Nebraska, Iowa, Wisconsin, Illinois, Indiana, Michigan, and Ohio... Bringing damaging winds upwards of 80-100MPH+, and significant/widespread damage. This derecho originated as scattered showers and t'storms across the South Dakota/Nebraska border very late Sunday night into very early Monday morning. This activity quickly grew upscale into a large complex, which quickly gained organization and severity as it moved across Northeast Nebraska, Southeast South Dakota and Western Iowa early to mid Monday morning. Continuing eastward, this complex fully matured and became most significant across Central to Eastern Iowa mid Monday morning into early Monday afternoon, from the Des Moines area on east into the Quad Cities area. During this time what is known and a bookend vortex was present within the complex, along with a strong rear inflow jet. The combination of these two features, along with a great environment and other factors, lead to a swath of 80-120MPH winds and widespread/severe damage across a several county wide corridor from near Des Moines eastward into the Quad Cities area. The extremely high wind gusts in excess of 80-120MPH over such a large area, along with the extent and severity of damage, is extremely rare and almost unheard of in this part of the country outside of a tornado. Damage in the Cedar Rapids mimics that of a fairly strong hurricane land-falling in the tropics. As this complex continued east into Illinois Monday afternoon, it quickly changed characteristics...With the main bookend vortex weakening, and the complex being more dominated by numerous meso-vorticies, which tend to enhance wind damage in smaller yet numerous corridors. This ended up being the case across much of Northern Illinois, where numerous swaths of 70-100MPH damaging winds occurred, along with at least 15 tornadoes. While moving through Illinois, the main derecho merged with another severe t'storm complex exiting Missouri into Western Illinois, which ended up impacting much of Central and Southern Illinois with damaging winds of 60-70MPH and some hail. Meanwhile, further north the main derecho continued on across Northern and Central Indiana, Southwest Michigan and Northwest Ohio Monday evening, with damaging winds of 60-80MPH. The derecho finally rapidly weakened and diminished early Monday night, deeper into Michigan, Ohio and Kentucky.
(11:30AM - 8/10/20) A disturbance moving through the region today will bring a severe t'storm threat across much of the state, including a higher end severe t'storm threat with significant and widespread damaging wind potential across Northern Illinois.
Summary... A large complex of severe t'storms with a history of producing widespread and significant damaging winds is ongoing this morning across Iowa. This complex originated from the South Dakota/Nebraska border very early this morning, and has since raced eastward into Central Iowa by late this morning. Along the path of this complex, widespread and significant damaging winds have occurred. This complex of severe t'storms will continue to race east-southeast across Eastern Iowa and into Northwest and Western Illinois early this afternoon, and eventually Northern and portions of Central Illinois by mid-late this afternoon. An environment in place ahead of this complex will feature high instability, moderate shear, good forcing, and high moisture...among other very supportive features. Upwards of a considerable to major severe t'storm threat will exist across Northern Illinois, where a widespread, significant and destructive damaging wind threat will exist with this likely derecho. Damaging winds of 60-100mph will be likely within the main risk corridor, along with the threat fir widespread and potentially significant damage. An isolated tornado threat will also exist with this complex, along with some large hail threat. Further south, additional scattered showers and t'storms will be likely across Central and Southern Illinois this afternoon into tonight, where upwards of a limited severe t'storm threat will exist. Damaging winds and large hail will be the main threats. Below is the severe t'storm forecast for this morning - tonight. 
(9:30PM - 8/9/20) A disturbance is expected to move through the region on Monday, bringing a low end threat for severe t'storms to much of the state.
Summary... A few areas of isolated to scattered showers and t'storms may be ongoing Monday morning across portions of Eastern Illinois, on into Indiana. A good deal of clearing and destabilization will occur across portions of the state on Monday. Areas of showers and t'storms that will have developed Sunday night across Nebraska, South Dakota, Minnesota and Iowa will be pushing towards the state by late Monday morning and early Monday afternoon. Additionally, new scattered showers and t'storms are expected to develop across portions of Missouri, Iowa, Western and Northern Illinois and Wisconsin during the afternoon. All of this activity, in the form of clusters/lines, will push east-southeast across the state, Monday afternoon into Monday night. An environment in place will feature moderate instability, high moisture, good shear and good forcing. Upwards of a minimal severe t'storm threat is expected across much of the state, with damaging winds and large hail being the main threats. It is looking increasingly possible that portions of the state will need an upgrade is severe t'storm probabilities in a future update. Below is the severe t'storm forecast for Monday morning - Monday night. 
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