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(8:00PM - 12/10/19) A weak and fast moving disturbance will bring a period of light snow to portions of Northern and Central Illinois, very late tonight through midday Wednesday.
An area of light snow will spread into Northwest Illinois very late tonight, between 2-3AM. this area of light snow will then spread across portions of Northern and Central Illinois through Wednesday morning, slowly ending from west to east across these areas during the mid morning to midday time-frame. Minor snowfall accumulation of a dusting to 1" is possible across portions of Northern and Central Illinois. Locally higher amounts of 1-2" are possible towards the Quad Cities area. Below is the TAM snowfall forecast for this event. 
JP
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(9:15PM - 11/27/19) Thanksgiving is upon us...While Thursday will be a dreary day overall across the state, no significant weather is expected. Mostly cloudy to cloudy skies are expected much of the day across the state. There is the chance for a few showers to move into Western and Southwest Illinois by evening, with more light/scattered precipitation possible across the state Thursday night. High temperatures will generally range from the upper 30's across Northern Illinois, to around 40 across Central Illinois, and the low to mid 40's across Southern Illinois.
Below is the Thanksgiving forecast. 
JP
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(9:15PM - 11/26/19) A storm system moving across the region tonight and Wednesday will bring an extended period of high winds to the state.
The high winds during this period will be a product of a quickly organizing and strengthening storm system, and associated strong jet streak aloft. 850mb winds aloft of 45-70kts is likely, with mixing potentially up near that level at times, which correlates to the expected high winds at the surface.
Winds have slowly been increasing across Central and Southern Illinois this evening, with wind gusts of 20-40mph now common across these areas. Wind gusts of 20-40mph will continue to be possible across the state tonight. A period of increased wind gusts will likely accompany an area of showers and t'storms overnight during the 11PM-4AM time-frame tonight across the state. Wind gusts with this activity will likely be in the 40-60mph range. Late tonight and early Wednesday morning through Wednesday afternoon, winds will increase even more. This will occur following the cold front passage, on the backside of the storm system. Wind gusts during this time will be in the 45-60mph range. Isolated higher wind gusts in excess of 60mph will be possible as well across Northern and Central Illinois. Winds will gradually diminish late Wednesday afternoon and evening across the state.
Due to the expected high wind gusts and prolonged nature, some tree damage and power outages will be possible across the state. Below is the TAM high wind forecast for this event. 
JP
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(8:00PM - 11/26/19) The same storm system that will bring high winds to the state tonight and Wednesday, will also bring a low end threat for strong and severe t'storms to the state tonight into early Wednesday morning.
As expected, broken lines of showers and t'storms have developed along and ahead of a cold front across Missouri this evening. This activity is expected to rapidly push northeastward, and will affect the state overnight. This activity will likely sweep northeastward across the state between an 11PM-4AM time-frame. An environment will be in place featuring 45-60 degree dew points and <1,000 J/KG CAPE. On the other end of the spectrum, shear will be on the high end of the scale. In other words, this is a low moisture/instability and high shear setup. By no means does this look like a significant or widespread severe weather event. However, given the time of year and holiday travel will be underway for some, it is noteworthy. There is a very low end threat for severe t'storms across the state during this period, with damaging/high winds being the greatest threat with this activity. High winds are already expected outside of showers and t'storms, but this activity could bring enhanced wind potential. Additionally, an isolated tornado cannot be ruled out given there will be some instability in place, coupled with the strong shear. Below is the TAM severe t'storm forecast for this event. 
JP
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(11:30AM - 11/26/19) The same storm system that will bring high winds to the state tonight and Wednesday, will also bring a low end threat for strong and severe t'storms to the state this evening into early Wednesday morning.
With this update we have expanded the low end chance for severe t'storms to the rest of the state. Otherwise, no additional changes were needed from the previous update.
One or more broken lines of showers and t'storms will develop along and ahead of a cold front, across portions of Iowa and Missouri, later this afternoon and evening. Ahead of this activity an environment will be in place featuring 50-60 degree dew points and <1,000 J/KG CAPE. On the other end of the spectrum, shear will be on the high end of the scale. In other words, this is a low moisture/instability and high shear setup. As the broken lines of showers and t'storms race northeastward across the state tonight, isolated strong to severe t'storms will be possible. By no means does this look like a significant or widespread severe weather event. However, given the time of year and holiday travel will be underway for some, it is noteworthy. Damaging/high winds will be the greatest threat with this activity. High winds are already expected outside of showers and t'storms, but this activity could bring enhanced wind potential. Additionally, an isolated tornado cannot be ruled out given there will be some instability in place, coupled with the strong shear. It is possible that portions of the state may need to be upgraded to higher severe probabilities in later updates.
Below is the TAM severe t'storm forecast for this event. 
JP
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(9:00PM - 11/25/19) The same storm system that will bring high winds to the state on Tuesday and Wednesday, will also bring a low end threat for strong and severe t'storms to the state.
A broken line of showers and t'storms is expected to develop along a cold front, across portions of Iowa and Missouri, late Tuesday afternoon and evening. Ahead of this activity an environment will be in place featuring 50-60 degree dew points and <1,000 J/KG CAPE. On the other end of the spectrum, shear will be on the high end of the scale. In other words, this is a low moisture/instability and high shear setup. As the broken line of showers and t'storms races northeastward across the state Tuesday night, isolated strong to severe t'storms will be possible. By no means does this look like a significant or widespread severe weather event. However, given the time of year and holiday travel will be underway for some, it is noteworthy. Damaging/high winds will be the greatest threat with this activity. High winds are already expected outside of showers and t'storms, but this activity could enhance the wind potential. Additionally, an isolated tornado cannot be ruled out given there will be some instability in place, coupled with the strong shear. Below is the TAM severe t'storm forecast for this event. 
JP
Please consider becoming a Patreon as a way to say thanks and support us for what we do! www.patreon.com/user?u=16598980 To receive text alerts via our in-telligent groups text ISC to 833-369-3800
(7:30PM - 11/25/19) A storm system is expected to move across the region Tuesday and Wednesday, which will bring an extended period of high winds to the state.
The high winds during this period will be a product of a quickly organizing and strengthening storm system, and associated strong jet streak aloft. 850mb winds aloft of 40-60kts is likely, with mixing potentially up near that level at times, which correlates to the expected high winds at the surface.
Winds will increase across the state late Tuesday afternoon and into Tuesday night, as the storm system enters the region. Wind gusts will increase to 20-40mph across the state during this time. Overnight Tuesday and into Wednesday afternoon, winds will increase even more. This will occur just ahead of a passing cold front, and on the backside of the storm system. Wind gusts during this time will be in the 45-60mph range. Isolated higher wind gusts in excess of 60mph will be possible as well. Winds will gradually diminish later Wednesday afternoon and evening across the state.
Due to the expected wind gusts and prolonged nature of higher wind gusts, some tree damage and power outages will be possible across the state. Below is the TAM high wind forecast for this event. 
JP
Please consider becoming a Patreon as a way to say thanks and support us for what we do! www.patreon.com/user?u=16598980 To receive text alerts via our in-telligent groups text ISC to 833-369-3800
(11:45AM - 11/25/19) A storm system is expected to move across the region Tuesday and Wednesday, and expected to bring high winds to the state.
Winds will increase across the state late Tuesday afternoon and into Tuesday night, as a storm system enters the region. Wind gusts will increase to 20-40mph across the state during this time. Overnight Tuesday and into Wednesday morning, wind gusts of 35-50mph will be likely across the state, along and ahead of a cold front sweeping across the state. Higher gusts of 50-55mph will be possible, especially in and around expected isolated to scattered thunderstorms. The rest of the day Wednesday will feature wind gusts of 30-50mph across the state, on the backside of the storm system. Winds will gradually diminish later Wednesday afternoon and evening across the state. Below is the TAM high wind forecast for this event. 
JP
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(4:00PM - 11/22/19) A storm system is expected to move across the region tonight into Saturday, which will affect portions of the state during this time.
As was outlined in our original post from Wednesday night, "Potential Weekend Accumulating Snow?", model guidance was showing a storm system potentially affecting the state during the time-frame of tonight into Saturday. Model guidance was significantly struggling with this system and the overall pattern, in a complex setup. Two scenarios were outlined in the original post... #1... The southern stream disturbance is slower at ejecting out into the Plains, with a northern stream disturbance digging into the Northern U.S. This would allow for partial phasing to occur, thus a more pronounced storm system with the potential for at least a couple inches of snow within a swath across the heart of the state. #2... The southern stream disturbance is faster and ejecting out, misses a partial phase with the northern stream disturbance, and is instead sheared out. This would lead to a very weak storm system, with little to no chance for snow across the state.  GFS model depiction for Saturday morning.
At the time of the original post, model guidance was fairly split between both scenarios, but slightly favored scenario #1...which resulted in the need for a post outlining the potential, especially given it was only 2-3 days away. Since that time, model guidance continued to struggle for a while, before finally coming into agreement on the original outlined scenario #2. With all of that said, a storm system is still expected to move across the region tonight into Saturday. Rain showers will be possible across Central and Southern Illinois during this time. With some cold air in place, some snow showers will be possible across Central Illinois and vicinity. Little to no snow accumulation is expected. This will likely be the last update regarding this storm system.
JP
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(9:30PM - 11/20/19) A storm system is expected to move across the region Friday into Saturday, which potentially could bring accumulating snow to portions of the state.
Over the past several days model guidance has been hinting at the potential for accumulating snow across portions of the state, Friday night into Saturday afternoon, as a storm system moves through the region. However, there has been a high amount of disagreement regarding this potential event...Ranging from no storm system at all on some model guidance, to a pronounced storm system with several inches of snow on other model guidance. The main issue giving model guidance a fuss is a complex scenario in place, which will feature a southern stream disturbance across the Inter-mountain West and a potential partial phase or shearing, with a northern stream disturbance dropping in from Canada. How these two disturbances evolve and interact will determine how the storm system evolves for the region.
Two scenarios are in play at this time...
#1... The southern stream disturbance is slower at ejecting out into the Plains, with a northern stream disturbance digging into the Northern U.S. This would allow for partial phasing to occur, thus a more pronounced storm system with the potential for at least a couple inches of snow within a swath across the heart of the state. #2... The southern stream disturbance is faster and ejecting out, misses a partial phase with the northern stream disturbance, and is instead sheared out. This would lead to a very weak storm system, with little to no chance for snow across the state. More recently, model guidance has been trending towards the above mentioned scenario #1. Further updates will be provided over the coming days. Note: On the below map, the area of "accumulation possible" does not mean you will see snowfall accumulation. This is merely a depiction of where the range of model guidance has would suggest accumulating snow would be possible, should it occur. 
JP
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