(11:45AM - 6/18/21) Multiple disturbances will continue to move through the region through Saturday, bringing periods of severe t'storm potential to portions of the state through Saturday night.

Summary...
Multiple disturbances will continue to eject out of the Plains, and push eastward across the Midwest and Great Lakes through Saturday. These disturbances will bring periods of severe t'storm potential to portions of the state, through Saturday night. With this update only minor changes were made tot he severe t'storm forecast for this afternoon-early Saturday morning. Additionally, level 1 severe t'storm probabilities were expanded a bit for the severe t'storm forecast for Saturday afternoon-late Saturday night. 

Forecast...
This Afternoon-Early Saturday Morning...
The complex of t'storms from Thursday night/this morning cleared the state area surrounding areas by mid morning. In the wake of this complex, another disturbance has quickly been pushing through the area late this morning and into this afternoon, bringing some scattered showers and isolated t'storms to portions of Central Illinois. With another disturbance expected to move through the area later today and tonight and a frontal boundary expected to be draped across the heart of the state, additional rounds of showers and t'storms are expected to develop this afternoon and evening across portions of Iowa, Northern Missouri and Northern and Central Illinois. This activity will then push east-southeastward this evening through tonight, affecting the heart of the state. An environment supportive of a severe t'storm threat will be in place. This environment will feature moderate to high instability of 3,000-5,000J/KG, dew points in the mid 60's to low 70's, good shear, good forcing, and high lapse rates of 7.0-8.0C. This environment will be supportive of upwards of a widely scattered to scattered severe t'storm risk (level 2-3) across the heart of the state. Damaging winds and large hail will be the main severe weather threats, though an isolated tornado cannot be ruled out.

Saturday Afternoon-Saturday Night...
A few lingering areas of showers and t'storms my be ongoing Saturday morning across Central and Southern Illinois, weakening and diminishing activity left over from Friday night. With a frontal boundary expected to be draped across the heart of the state and another disturbance or two set to move through, areas of showers and t'storms will develop Saturday afternoon across the heart of the state. This activity will spread east-southeastward across portions of Central and Southern Illinois, Saturday afternoon through late Saturday night. An environment supportive of a severe t'storm threat will be in place. This environment will feature moderate to high instability of 3,000-5,000J/KG, dew points in the mid 60's to low 70's, good shear, good forcing, and high lapse rates of 6.0-7.5C. This environment will be supportive of upwards of a an isolated severe t'storm risk (level 1) across the heart of the state. Damaging winds and hail will be the main severe weather threats, though an isolated tornado cannot be ruled out.

​Below is the severe t'storm forecasts for this event.

​Recap
Thursday Evening-Friday Morning...
As expected, a large complex of rain and t'storms developed across Western Wisconsin, Southern Minnesota and Northern Iowa Thursday evening. This complex featured numerous severe t'storms Thursday evening and early Thursday night across Western and Central Wisconsin and Southern Minnesota. This complex then pushed southeastward across Central and Southern Wisconsin, Northern Illinois, Northern Indiana and Southern Michigan, Thursday night into Friday early morning. While there were no severe t'storms that occurred while traversing Northern Illinois with this complex Thursday night and early Friday morning, some areas received strong non-severe winds of 45-55MPH, including across the Chicago metro area.

JP

(11:30PM - 6/17/20) A period of hot and humid conditions has settled into portions of the region, and will affect portions of the state through Sunday.

Summary....
A strong ridge has been in place across the Southwestern US for the past several days, leading to very hot and record temperatures out that way. An extension of this ridge is briefly extending into the Plains for this period of time, which will allow hot and humid conditions to affect portions of Central and Southern Illinois through Sunday.

Forecast For Next Two Days...
Friday, June 18th Forecast...
High temperatures will range from the mid to upper 90's across much of Central and Southern Illinois, with low temperatures ranging from the upper 60's to mid 70's. Heat index values will be in the upper 90's to mid 100's.

Further north, the heat will be tempered, with high temps expected to be in the upper 80's to mid 90's across Northern Illinois.

Saturday, June 19th Forecast...
High temperatures will range from the low to upper 90's across much of Central and Southern Illinois, with low temperatures ranging from the upper 60's to mid 70's. Heat index values will be in the mid 90's to mid 100's.

Further north, the heat will be tempered, with high temps expected to be in the low 80's to low 90's across Northern Illinois.

​Recap Summary...
Thursday, June 17th Recap...
High temperatures topped out in the low to mid 90's across Western and Southwestern Illinois, and low temps in the low to mid 60's. Heat index values were in the low to upper 90's.

​Elsewhere across the state, high temps were in the mid 80's to low 90's.

JP

(11:00PM - 6/17/21) Multiple disturbances will move through the region through Saturday, bringing periods of severe t'storm potential to portions of the state tonight through Saturday night.

Summary...
Multiple disturbances will eject out of the Plains, and push eastward across the Midwest and Great Lakes through Saturday. These disturbances will bring periods of severe t'storm potential to portions of the state, tonight through Saturday night. With this update we have trimmed back severe t'storm probabilities for tonight/early Friday morning based on observational trends. The forecast for Friday through early Saturday morning needed little to no change.

Forecast...
Tonight-Friday Morning...
A large complex of severe t'storms developed this evening across portions of Southeast Minnesota into Central Wisconsin. This activity developed a bit further north than originally anticipated, due to a slightly stronger cap than previously modeled. Additional back building has continued to occur across Southern Minnesota and Northern Iowa, with the main complex then located to the east from the Minnesota/Wisconsin border on east into Central Wisconsin. This complex will continue to push east-southeastward overnight, and still has the potential to affect portions of Northern Illinois overnight and into very early Friday morning. Ahead of this activity, an environment supportive of a severe t'storm threat continue to advect in, as it has through the day today. This environment features moderate instability of 2,000-4,000J/KG, dew points well into the 60's, good shear, good forcing, and high lapse rates of 7.5-8.5C. This environment will be supportive of upwards of an isolated to widely scattered severe t'storm risk (level 1-2) across portions of Northern Illinois during this time. Damaging winds and hail will be the main severe weather threats.

​Friday Afternoon-Friday Night...
The complex(s) of t'storms from tonight/Friday morning is expected to clear the state by mid Friday morning. With another disturbance or two expected to move through the area and a frontal boundary expected to be draped across the heart of the state, additional rounds of showers and t'storms are expected to develop Friday afternoon and evening across portions of Northern and Central Illinois. This activity will then push southeastward Friday evening into Friday night, affecting the heart of the state. An environment supportive of a severe t'storm threat will be in place. This environment will feature moderate to high instability of 3,000-5,000J/KG, dew points in the mid 60's to low 70's, good shear, good forcing, and high lapse rates of 7.0-8.0C. This environment will be supportive of upwards of a widely scattered to scattered severe t'storm risk (level 2-3) across the heart of the state. Damaging winds and hail will be the main severe weather threats, though an isolated tornado cannot be ruled out.

Saturday Afternoon-Saturday Night...
With a frontal boundary expected to be draped across the heart of the state and another disturbance or two set to move through, another round of showers and t'storms will develop Saturday afternoon across the heart of the state. This activity will spread eastward across portions of Central and Southern Illinois, Saturday afternoon through Saturday night. An environment supportive of a severe t'storm threat will be in place. This environment will feature moderate to high instability of 3,000-5,000J/KG, dew points in the mid 60's to low 70's, good shear, good forcing, and high lapse rates of 6.0-7.5C. This environment will be supportive of upwards of a an isolated severe t'storm risk (level 1) across the heart of the state. Damaging winds and hail will be the main severe weather threats, though an isolated tornado cannot be ruled out.

​Below is the severe t'storm forecasts for this event.

JP

(11:00AM - 6/17/21) Multiple disturbances will move through the region today through Saturday, bringing periods of severe t'storm potential to portions of the state, this evening through Saturday night.

Summary...
Multiple disturbances will eject out of the Plains, and push eastward across the Midwest and Great Lakes, today through Saturday. These disturbances will bring periods of severe t'storm potential to portions of the state, this evening through Saturday night. Model guidance has been showing potential during this time frame for a few days now, and  continues to be in fairly good agreement regarding the expected evolution. Only minor changes were needed with this update.

​Forecast...
Thursday Evening-Friday Morning...
At least one or two disturbances are expected to eject out of the Plains and into the Midwest on today. This will lead to the development of severe t'storms this afternoon, across Western Wisconsin, Southern Minnesota and Northern Iowa. This activity is likely to grow upscale into at least one complex, which will then push east-southeast this evening through Friday morning. This complex(s) is expected to push across Northern Illinois overnight tonight. Ahead of this activity, an environment supportive of a severe t'storm threat will be advecting in. This environment will feature moderate instability of 2,000-4,000J/KG, dew points well into the 60's, good shear, good forcing, and high lapse rates of 7.5-8.5C. This environment will be supportive of upwards of a widely scattered to scattered severe t'storm risk (level 2-3) across Northern Illinois during this time. Damaging winds and hail will be the main severe weather threats.

​Friday Afternoon-Friday Night...
The complex(s) of t'storms from Thursday night/Friday morning is expected to clear the state by later Friday morning, allowing for clearing and destabilization to occur. With another disturbance or two expected to move through the area and a frontal boundary expected to be draped across the heart of the state, a new round of showers and t'storms is expected to develop later Friday afternoon and evening across portions of Northern and Central Illinois. This activity will then push southeastward Friday evening into Friday night, affecting the heart of the state. An environment supportive of a severe t'storm threat will be in place. This environment will feature moderate to high instability of 3,000-5,000J/KG, dew points in the mid 60's to low 70's, good shear, good forcing, and high lapse rates of 7.0-8.0C. This environment will be supportive of upwards of a widely scattered to scattered severe t'storm risk (level 2-3) across the heart of the state. Damaging winds and hail will be the main severe weather threats, though an isolated tornado cannot be ruled out.

Saturday Afternoon-Saturday Night...
With a frontal boundary expected to be draped across Central and Southern Illinois and another disturbance set to move through, isolated to scattered showers and t'storms are likely to develop Saturday afternoon. This activity will then affect portions of Central and Southern Illinois into Saturday night. Some of this activity could pose a severe threat, and will be addressed in future updates.

​Below is the severe t'storm forecasts for this event.

JP

(9:30PM - 6/16/21) Multiple disturbances will move through the region Thursday and Friday, bringing the risk for severe t'storms to much of the state, Thursday evening through Friday night.

Summary...
Multiple disturbances will eject out of the Plains, and push eastward across the Midwest and Great Lakes on Thursday and Friday. These disturbances will bring a severe t'storm risk to much of the state, Thursday evening through Friday night. Model guidance has been showing potential during this time frame for a few days now, and  continues to be in fairly good agreement regarding the expected evolution. Only minor changes were needed with this update.

​Forecast...
Thursday Evening-Friday Morning...
At least one or two disturbances are expected to eject out of the Plains and into the Midwest on Thursday. This will lead to the development of severe t'storms Thursday afternoon, from Southern Minnesota down into Iowa. This activity is likely to grow upscale into at least one complex, which will then push east-southeast Thursday evening through Friday morning. This complex(s) is then expected to push across Northern Illinois, late Thursday evening through early Friday morning. Ahead of this activity, an environment supportive of a severe t'storm threat will be advecting in. This environment will feature moderate instability of 2,000-4,000J/KG, dew points well into the 60's, good shear, good forcing, and high lapse rates of 7.5-8.5C. This environment will be supportive of at least an isolated to widely scattered severe t'storm risk (level 1-2) across Northern Illinois during this time. Damaging winds and hail will be the main severe weather threats.

Friday Afternoon-Friday Night...
The complex(s) of t'storms from Thursday night/Friday morning is expected to clear the state by Friday afternoon, allowing for clearing and destabilization to occur. With another disturbance expected to move through the area and a frontal boundary expected to be draped across the heart of the state, a new round of showers and t'storms is expected to develop later Friday afternoon across Central Illinois. This activity will then push southeastward Friday evening into Friday night, affecting portions of Central and Southern Illinois. Across Central and Southern Illinois, an environment supportive of a severe t'storm threat will be in place. This environment will feature moderate to high instability of 3,000-5,000J/KG, dew points in the mid 60's to low 70's, good shear, good forcing, and high lapse rates of 7.0-8.0C. This environment will be supportive of at least an isolated to widely scattered severe t'storm risk (level 1-2) across Central and Southern Illinois during this time. Damaging winds and hail will be the main severe weather threats.

​Below is the severe t'storm forecasts for this event.

JP

(11:30AM - 6/16/21) Multiple disturbances will move through the region Thursday and Friday, bringing the risk for severe t'storms to much of the state, Thursday evening through Friday night.

Summary...
Multiple disturbances will eject out of the Plains, and push eastward across the Midwest and Great Lakes on Thursday and Friday. These disturbances will bring a severe t'storm risk to much of the state, Thursday evening through Friday night. Model guidance has been showing potential during this time frame for a few days now, and is in fairly good agreement regarding the expected evolution.

​Forecast...
Thursday Evening-Friday Morning...
A disturbance is expected to eject out of the Plains and into the Midwest on Thursday. This will lead to the development of severe t'storms across Southern Minnesota down into Central Iowa Thursday afternoon. This activity is likely to grow upscale into a complex, which will then push east-southeast Thursday evening through Friday morning. This complex is expected to push across Northern Illinois, late Thursday evening through early Friday morning. Ahead of this complex, an environment supportive of a severe t'storm threat will be advecting in. This environment will feature moderate instability of 2,000-4,000J/KG, dew points well into the 60's, good shear, good forcing, and high lapse rates of 7.5-8.5C. This environment will be supportive of at least an isolated to widely scattered severe t'storm risk (level 1-2) across Northern Illinois during this time. Damaging winds and hail will be the main severe weather threats.

Friday Afternoon-Friday Night...
The complex of t'storms from Thursday night/Friday morning is expected to clear the state by Friday afternoon, allowing for clearing and destabilization to occur. With another disturbance expected to move through the area and a frontal boundary expected to be draped across the heart of the state, a new round of showers and t'storms is expected to develop later Friday afternoon across Central Illinois. This activity will then push southeastward Friday evening into Friday night, affecting portions of Central and Southern Illinois. Across Central and Southern Illinois, an environment supportive of a severe t'storm threat will be in place. This environment will feature moderate to high instability of 3,000-5,000J/KG, dew points in the mid 60's to low 70's, good shear, good forcing, and high lapse rates of 7.0-8.0C. This environment will be supportive of at least an isolated to widely scattered severe t'storm risk (level 1-2) across Central and Southern Illinois during this time. Damaging winds and hail will be the main severe weather threats.

​Below is the severe t'storm forecast for Thursday evening-Friday morning.

JP

(8:15AM - 5/27/21) A storm system moving through the region through Friday, will bring the risk for severe t'storms to Central and Southern Illinois, this morning through late tonight.

Summary...
A storm system that moved through the Plains on Wednesday will move through the Midwest and Mid-Mississippi Valley today, and eventually the Ohio Valley on Friday. This storm system will bring a severe t'storm risk to Central and Southern Illinois, this morning through late tonight. Real time observations continue to support the overall previous forecast, with just minor changes needed.

​Forecast...
Model guidance had been showing several potential scenarios for this time period the past several days... However, there had been one solution within model guidance that had been heavily weighed in our previous forecasts. This solution is looking increasingly likely to occur, given continued/increased model support and now real time observational trends support it as well tonight.

As expected, a large complex of severe t'storms developed across the Plains last evening. This complex continued eastward overnight, and will be pushing into Northwest and Western Illinois this morning in a much weaker phase. This complex is then expected to push eastward across much of the state this morning and this afternoon, as it continues to overall fade and weaken with eastward extent. However, with a marginal environment expected to develop with time across Central and Southern Illinois, some regeneration is possible. This could lead to an isolated to widely scattered severe t'storm across portions of Central and Southern Illinois, this morning into this afternoon. Damaging winds, hail and an isolated tornado will be the severe weather threats.

In the wake of this initial complex, additional severe t'storm may develop out west along a cold front, across Kansas and Missouri this afternoon. Uncertainty revolves around this potential, in the wake of early day activity. Should this activity develop, it would then push eastward and eventually across Central and Southern Illinois, this evening through later tonight. A marginal environment will still be in place, which will support an isolated to widely scattered severe t'storm risk. Damaging winds, hail and an isolated tornado will be the severe weather threats.

​Below is the severe t'storm forecast for this event.

JP

(10:00PM - 5/26/21) A storm system will move through the region tonight through Friday, bringing the risk for severe t'storms to Central and Southern Illinois, Thursday morning through late Thursday night.

Summary...
A storm system will move from the Plains tonight, through the Midwest and Mid-Mississippi Valley on Thursday, and eventually the Ohio Valley on Friday. This storm system will bring a severe t'storm risk to Central and Southern Illinois, Thursday morning through late Thursday night. Model guidance continues to show this potential, though agreement on specifics for the event has increased.

​Forecast...
Model guidance had been showing several potential scenarios for this time period the past several days... However, there had been one solution within model guidance that had been heavily weighed in our previous forecasts. This solution is looking increasingly likely to occur, given continued/increased model support and now real time observational trends support it as well tonight.

The first focus is a complex of severe t'storms that is originating across the Plains this afternoon and evening. This complex is expected to move into the western half of the state by Thursday morning, in a much weaker phase. However, with a marginal environment developing ahead of this complex, some of this activity could remain strong/severe as well as the potential for some regeneration of this activity, which could pose an isolated to widely scattered severe t'storm risk across portions of Central and Southern Illinois, Thursday morning into Thursday afternoon. Damaging winds, hail and an isolated tornado will be the severe weather threats.

In the wake of this initial complex, additional severe t'storm may develop out west across Kansas and Missouri Thursday afternoon. Uncertainty revolves around this potential, in the wake of early day activity. Should this activity develop, it would then push eastward and eventually across Central and Southern Illinois Thursday evening through later Thursday night. A marginal environment will still be in place, which will support an isolated to widely scattered severe t'storm risk. Damaging winds, hail and an isolated tornado will be the severe weather threats.

​Below is the severe t'storm forecast for this event.

JP

(9:30PM - 5/25/21) A storm system will move through the region Wednesday through Friday, bringing the risk for severe t'storms to Central and Southern Illinois, Thursday morning through Friday morning.

Summary...
A storm system will move from the Plains on Wednesday, through the Midwest and Mid-Mississippi Valley on Thursday, and eventually the Ohio Valley on Friday. This storm system will bring a severe t'storm risk to Central and Southern Illinois, Thursday morning through Friday morning. Model guidance has been showing this potential for several days, though a large amount of disagreement still exists regarding how the overall event will unfold.

​Forecast...
A few potential scenarios are in play for this event, from Thursday morning through Friday morning... However, the most favored solution within model guidance is also preferred solution, given the model support and past history in similar events.

The first focus will be a complex of severe t'storms that originates across the Plains Wednesday afternoon and Wednesday night. This complex is expected to move into the western half of the state by Thursday morning, in a much weaker phase. However, with a marginal environment developing ahead of this complex, there could be some regeneration of activity, which could pose an isolated to widely scattered severe t'storm risk across portions of Central and Southern Illinois, Thursday morning into Thursday afternoon. Damaging winds, hail and an isolated tornado will be the severe weather threats.

In the wake of this initial complex, additional severe t'storm are likely to develop out west across Kansas and Missouri Thursday afternoon. This activity will then push eastward, and eventually across Central and Southern Illinois Thursday evening through Friday morning. A marginal environment will still be in place, which will support an isolated to widely scattered severe t'storm risk. Damaging winds, hail and an isolated tornado will be the severe weather threats.

​Below is the severe t'storm forecast for this event.

JP

(10:30AM - 5/8/21) A storm system will move through the region today and Sunday, bringing a low end/isolated severe t'storm risk, windy conditions, heavy rainfall and snow to portions of the state.

Summary...
A storm system will eject out across the Plains on today, then pushing through the Ohio Valley on Sunday. This storm system will bring a low end/isolated severe t'storm risk, windy conditions, heavy rainfall and snow to portions of the state. Model guidance continues to be in overall good agreement with all aspects of this storm system, with little to no change needed with this update.

​Forecast...
...Severe T'Storm Risk...

Saturday Night-Sunday Morning:
A complex of rain and t'storms that will be moving across portions of Nebraska, Kansas, Iowa and Missouri Saturday evening, is expected to southeastward across Central and Southern Illinois, overnight Saturday night and into Sunday morning. Ahead of this activity, elevated instability of 500-1,500J/KG and lapse rates of 7-9C will be advecting in. Combined with decent shear and decent forcing, this will allow for an isolated (level 1) severe t'storm risk to be possible across portion of far Western, far Southwest and far Southern Illinois...Overnight Saturday night and into Sunday morning. Damaging winds and hail will be the main threats.

Sunday Morning-Sunday Evening:
In the wake of early day activity, some clearing and destabilization may occurring ahead of the main storm system and trailing cold front. Additional scattered showers and t'storms are expected to develop along this cold front, across portions of Southern Illinois, Missouri and Arkansas. This activity will then push eastward, affecting Southern Illinois, Sunday afternoon and early evening. A marginal environment featuring instability of 250-1,000J/KG, dew points of 56-63, good forcing and good shear is expected to be in place. Given the aforementioned environment expected, this will set the stage for an isolated (level 1) severe t'storm risk across Southern Illinois, late Sunday morning through early Sunday evening. Hail, damaging winds and an isolated tornado will be possible.

...Windy Conditions...
High winds aloft, characterized by a low level jet of 45-70KT, will be in place. Mixing depths will support wind gusts of 30-45MPH across much of the state, Saturday night through Sunday afternoon. Winds will be northeasterly across Northern and Central Illinois, and southerly across Southern Illinois.

If that is not enough, a large portion of Northern and Central Illinois is expected to receive 1-2" of rainfall with this storm system. This is much needed rainfall, given a large portion of the state is seeing drought conditions. In addition to the rain, portions of Northern Illinois may see a rain/snow mix or a period of all snow, later tonight on into early Sunday morning. Some areas could see a dusting of snow.

​Below are the severe t'storm and wind forecasts for this event.

JP