(11:55PM - 5/16/19) A frontal boundary lingering in the area, several disturbances moving through the region, and the ejection of a main storm system...will bring the chance for severe t'storms to portions of the state Thursday through Sunday.

Tonight...
Widespread showers and t'storms have been ongoing since this evening across a good portion of Northern Illinois. Several of these storms have been severe, with hail having been the most common threat. Periods of showers and t'storms will continue overnight across much of Northern and portions of Central Illinois, with a continued isolated to scattered severe t'storm threat at times given a favorable environment, though the threat will gradually diminish with time overnight. Hail and winds will be the main threats.

Friday morning through night...
It looks likely that there will be several periods of showers and t'storms across much of Northern and portions of Central Illinois from Friday morning through Friday evening. Most of this activity will likely be north of a warm front in place across the region, which will extend across Central Illinois. With some elevated instability in place, an isolated strong to severe t'storm is possible. Hail would be the main threat should any storm reach those levels.

Saturday morning through night...
Weakening areas of showers and scattered t'storms will be possible across Northwest, Western and Southwest Illinois late Saturday morning into the afternoon. It looks plausible at this time that some clearing and destabilization will occur between and in the wake of said earlier activity, which would allow regeneration or new development of scattered showers and t'storms during the afternoon across the aforementioned areas and in adjacent states to the west. This activity will then also push northeast across much of the state, though in scattered fashion, into Saturday evening and night. An environment in place featuring low instability, decent moisture and good shear will aide in an isolated severe t'storm threat for some areas. Wind and hail will be the biggest threats, though an isolated tornado cannot be ruled out.

A severe threat may also continue into Sunday for portions of the state, with this being further discussed in future updates.

​Below is our updated TAM severe t'storm forecast for each day of the event.

​JP

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​(12:00PM - 5/16/19) A frontal boundary lingering in the area, several disturbances moving through the region, and the ejection of a main storm system...will bring the chance for severe t'storms to portions of the state Thursday through Sunday.

This afternoon through tonight...
A complex of showers and t'storms has been ongoing this morning across portions of Southern Wisconsin and Northern Illinois. This activity has regenerated and strengthened, becoming severe. This renewed complex of showers and t'storms will likely push southeast during the afternoon and evening, along an instability gradient that exists in the vicinity of the Illinois/Indiana border. All modes of severe weather will be possible with this activity.

In the wake of the aforementioned activity, additional isolated shower and t'storm development will be possible across Iowa, Southern Wisconsin and Northern Illinois this afternoon and evening, along an advancing cold front and remnant outflow boundary. The expected environment in place across these areas will feature high instability, good moisture and good shear. As another disturbance moves into the region during the afternoon, it looks possible that there will be enough forcing to overcome a cap in place. At this time will forecast isolated coverage during the afternoon and evening, becoming more widespread by early tonight and continuing overnight. Given the aforementioned environment expected, isolated severe t'storms are possible. All modes of severe weather are possible, including an isolated tornado threat early on.

​Friday morning through night...
It looks likely that there will be several periods of showers and t'storms across portions of Northern and Central Illinois from Friday morning through Friday night. An isolated strong to severe t'storm threat will exist with each round of activity. Wind and hail will be the main threats. 

​It should be noted that a severe t'storm threat will likely extend beyond Friday night, on into Sunday, for portions of the state. Additional information regarding the potential on each of those days will be discussed in later updates.

​Below is our updated TAM severe t'storm forecast for each day of the event.

​JP

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(9:30PM - 5/15/19) A disturbance pushing through the region, along with a favorable northwest flow pattern, will set the stage for severe weather potential on Thursday. Additional periods of severe weather potential are then likely across portions of the state Fri-Sun...

Will continue with previous forecast for Thursday with this update, as guidance and thoughts regarding the scenario expected to unfold continues to stay fairly consistent. Severe weather potential for Fri-Sun will be discussed further on Friday's update.

​Previous forecast...
A complex of showers and t'storms will likely be ongoing across portions of Wisconsin and nearby areas Thursday morning. At this time it looks likely that this complex will push southeast, and across portions of Northern Illinois Thursday morning and potentially into the early afternoon. Given an increasingly favorable environment will be in place with time, an isolated strong to severe t'storm is possible with this activity.

The main focus will be Thursday afternoon into night, across much of Northern and possibly portions of Central Illinois. In the wake of morning and early afternoon activity, an increasingly favorable environment for severe t'storms will develop across Northern Illinois. The expected environment will feature high instability, good moisture and good shear. As another disturbance moves into the region during the afternoon, it looks fairly possible that there will be enough forcing to overcome a cap in place. At this time it looks as though new shower and t'storm development could potentially occur in Northern Illinois along an outflow boundary left over from the early day activity...As well as along a cold front pushing across Wisconsin, Iowa and Northern Illinois during the afternoon and evening. At this time will forecast isolated coverage during the afternoon and evening, becoming more widespread by early Thursday night. Given the aforementioned environment expected, some severe t'storms are likely. All modes of severe weather are possible, including a tornado threat. An upgrade in severe probabilities is possible in subsequent outlooks if conditions warrant.

It should be noted that a severe t'storm threat will likely extend beyond Thursday night, on into Sunday, for portions of the state. Additional information regarding the potential on each of those days will be discussed in later updates.

​Below is our updated TAM severe t'storm forecast for this event.

​JP

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(11:55AM - 5/15/19) A disturbance pushing through the region, along with a favorable northwest flow pattern, will set the stage for severe weather potential on Thursday...

A complex of showers and t'storms will likely be ongoing across portions of Wisconsin and nearby areas Thursday morning. At this time it looks likely that this complex will push southeast, and across portions of Northern Illinois Thursday morning and potentially into the early afternoon. Given an increasingly favorable environment will be in place with time, an isolated strong to severe t'storm is possible with this activity.

​The main focus will be Thursday afternoon into night, across much of Northern and possibly portions of Central Illinois. In the wake of morning and early afternoon activity, an increasingly favorable environment for severe t'storms will develop across Northern Illinois. The expected environment will feature high instability, good moisture and good shear. As another disturbance moves into the region during the afternoon, it looks fairly possible that there will be enough forcing to overcome a cap in place. At this time it looks as though new shower and t'storm development could potentially occur in Northern Illinois along an outflow boundary left over from the early day activity...As well as along a cold front pushing across Wisconsin, Iowa and Northern Illinois during the afternoon and evening. At this time will forecast isolated coverage during the afternoon and evening, becoming more widespread by early Thursday night. Given the aforementioned environment expected, some severe t'storms are likely. All modes of severe weather are possible, including a tornado threat. An upgrade in severe probabilities is possible in subsequent outlooks if conditions warrant.

It should be noted that a severe t'storm threat will likely extend beyond Thursday night, on into Sunday, for portions of the state. Additional information regarding the potential on each of those days will be discussed in later updates.

​Below is our first TAM severe t'storm forecast for this event.

JP

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(5:00PM - 5/8/19) Late afternoon update regarding another day with severe t’storm potential across portions of the state today into tonight.

As you recall, in our update this afternoon we upped severe weather probabilities across portions of Northern and Western Illinois based on model guidance and observations suggesting a higher threat of severe weather for this afternoon and evening. Well, as is usual with our ever changing weather, it changed. A large area of clouds and rain moved back into much of Northwest, Western and Southwest Illinois...or across much of the prime area that was of focus for the better severe weather threat. Because of this, the chance of severe weather has now greatly decreased for the area previously in higher probabilities across portions of Northern and Western Illinois. With this update we will revert back to our earlier forecasts of just a very low end chance of an isolated strong to severe t’storm across the state through tonight, as periods of rain and t’storm are likely. Wind and hail would be the main threats should any t’storm reach those limits, and an isolated tornado cannot be ruled out closer to the warm front in Northern Illinois.

​Below is our updated TAM severe weather forecast for today and tonight.

JP

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(1:30PM - 5/8/19) Midday update regarding another day with severe t’storm potential across portions of the state.

As was previously discussed, there were two potential scenarios for today’s threat. Model guidance and observations suggest the second scenario is looking more likely with time. With that said...In the wake for morning showers and isolated t’storm across portions of Northern and Central Illinois, a warm front is rapidly lifting northward across the state. This warm front started across Southern Illinois this morning, and will make it to Northern Illinois by later this afternoon. South of this warm front an environment will be in place featuring modest instability, good moisture, and good shear. Scattered showers and t’storm a are expected to develop across Northwest Missouri, Eastern Iowa, Northwest and Western Illinois this afternoon. This activity will then spread northeast across much of Northern and portions of Central Illinois. Given the aforementioned environment in place, some severe t’storm are possible. All modes of severe weather are possible, including a tornado threat near the triple point and warm front...Across Western and Northwest Illinois.

In addition to the aforementioned activity from this afternoon into early tonight, additional periods of rain and t’storm a will push across much of the state from this evening into tonight. An isolated strong to severe t’storm is possible, with wind and hail the main threats.

Below is our updated TAM severe weather forecast for today.

JP

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​(5:55AM - 5/8/19) After rainy and stormy periods the past few days, the main storm system will finally begin to eject out into the region, bringing one final day of severe t'storm potential to portions of the state on Wednesday.

Wednesday afternoon and night...
Scattered showers and isolated t'storms have been spreading northward across portions of Northern and Central this morning, and will continue to into late morning. In the wake of this activity, a warm front will push northward across the state, making it into Northern Illinois during the afternoon. Two scenarios are still possible for today. The first scenario is a large complex of rain and t'storm pushes into the state during the afternoon in a weakening phase, and lingers much of the day. This would lead to little potential clearing and destabilization, thus little to no severe weather threat. In the second scenario...Enough clearing and destabilization would likely occur ahead of the approaching weakening large complex of rain and t'storms, redevelopment of new activity would likely occur in the vicinity of the IL/IA/MO border area. This activity would then spread across portions of Northern and Central Illinois into early Wednesday night. This activity would be in an environment featuring modest instability, modest moisture and good shear. This environment will help support a low end severe t'storm threat. Wind and hail would be the main threats with any strong to severe t'storm. Sounding also show a tornado threat would exist as well. For now will go with the middle ground between each solution, though slightly favoring the first solution given past history in similar situations. Should the second scenario eventually look more likely, higher severe weather probabilities would be needed.

Below is our updated TAM severe weather forecasts for the event.

JP

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(12:30PM - 5/6/19) Multiple disturbances pushing through the region this upcoming week will bring several rounds of rain and t'storms to the state, leading to high rainfall totals and flood potential.

After a wet week with widespread high rainfall totals and flooding for the state last week, another wet period is on the way for this upcoming week. A lingering frontal boundary with several disturbances moving through the region will bring several periods of rain and t'storms to much of the state from now through Thursday. During this period, there will be a some rounds of more organized activity.

Things kicked off Sunday evening into this evening...With areas of rain and isolated t'storms affecting portions of Northern and Central Illinois. Areas of rain then continued across portions of Northern and Central Illinois Monday and Monday night. Rainfall totals with this round generally stayed under 0.50" for affected areas, though isolated corridors in Central Illinois received in excess of 1-3” of rain.

The next more organized round of rain and t'storms will affect much of the state this evening into Wednesday night. Widespread rainfall amounts from this round will be up to 0.50", with corridors of 1-3” of rain possible.

Final rainfall totals will likely end up around or in excess of 1" across a decent portion of the state during this period, with areas of higher rainfall totals likely. It is looking more likely as time goes on that areas of 2-5" rainfall totals may be possible across portions of Northern and Central Illinois, which will promote more widespread minor to moderate flooding potential across this area. Given it has been overall wet the past few months across portions of the state, combined with the expected heavy rainfall totals, widespread minor flood potential is likely.

Below is our updated TAM flood forecast.

JP

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​(12:00PM - 5/7/19) A frontal boundary lingering across the state with disturbances moving through, will aide in promoting a very low end severe threat across portions of the state Monday through Wednesday.

This afternoon and tonight...
In the wake of early day showers and isolated t'storms across Northern, Central and Southwest Illinois...New development of isolated showers and t'storms will occur along a cold front across Central and Southern Illinois during the afternoon. This activity will be in an environment featuring modest instability, modest moisture and modest shear. This environment will help support a very low end strong to severe t'storm threat. Wind and hail will be the main threats with any strong to severe t'storm. Activity will persist across Central and Southern Illinois into tonight.

Wednesday afternoon and night...
Scattered showers and isolated t'storms will likely be spreading across portions of the state Wednesday morning. In the wake of this activity, a warm front will push northward across the state, making it into Northern Illinois during the afternoon. Two scenarios are possible for Wednesday. The first scenario is a large complex of rain and t'storm pushes into the state and lingers much of the day, with little to no severe weather threat. In the second scenario...Should enough clearing and destabilization occur ahead of the approaching large complex of rain and t'storms, redevelopment and strengthening would occur. This activity would then spread across much of the state into the evening. This activity would be in an environment featuring modest instability, modest moisture and decent shear. This environment will help support a low end strong to severe t'storm threat. Wind and hail would be the main threats with any strong to severe t'storm. For now will go with the middle ground between each solution, though slightly favoring the first solution given past history in similar situations. Should the second scenario eventually look more likely, higher severe weather probabilities would be needed.

Below is our updated TAM severe weather forecasts for each day.

JP

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(10:00PM - 5/6/19) Multiple disturbances pushing through the region this upcoming week will bring several rounds of rain and t'storms to the state, leading to high rainfall totals and flood potential.

After a wet week with widespread high rainfall totals and flooding for the state last week, another wet period is on the way for this upcoming week. A lingering frontal boundary with several disturbances moving through the region will bring several periods of rain and t'storms to much of the state from now through Thursday. During this period, there will be a some rounds of more organized activity.

Things kicked off Sunday evening into this evening...With areas of rain and isolated t'storms affecting portions of Northern and Central Illinois. Rainfall totals with this round generally stayed under 0.50", though isolated corridors in Central Illinois have received in excess of 1” of rain.

The second more organized round of rain and t'storms will affect much of the state Tuesday morning into Wednesday morning. Widespread rainfall amounts from this round will be up to 0.50, with corridors of 1-3” of rain possible. The third round will affect much of the state, from Wednesday morning into Thursday evening.

Final rainfall totals will likely end up around or in excess of 1" across a decent portion of the state during this period, with areas of higher rainfall totals likely. It is looking more likely as time goes on that areas of 1-4" rainfall totals may be possible across portions of Northern Illinois, which will promote more widespread minor to moderate flooding potential across this area. Given it has been overall wet the past few months across portions of the state, combined with the expected heavy rainfall totals, widespread minor flood potential is likely.

Below is our updated TAM flood forecast.

JP

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