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(8:30PM - 1/27/20) A weakening storm system moving through the region will bring the chance for wintry precipitation to portions of the state, Tuesday night through Wednesday night.
A storm system is expected to eject out of the Rockies, and move through the Southern Plains and Southern Mississippi Valley Tuesday and Wednesday. This storm system will be in a weakening trend with time, but will still bring a period of light precipitation to the state Tuesday night through Wednesday night. An area of precipitation will first enter Southern Illinois Tuesday night, in the form of a mix. Snow will then spread into Western and Southwest Illinois later Tuesday night and early Wednesday morning. Snow will then be possible from Wednesday morning through Wednesday evening, before ending from west to east. Minor snowfall accumulation of a dusting to 1.5" will be likely across portions of Central and Southern Illinois.
Below is the TAM snowfall forecast for this event. 
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(3:00PM - 1/27/20) Post storm wrap up regarding the recent Wed-Fri, January 22-25th winter storm that affected the state. During this period, a long duration event occurred, with low to moderate snowfall accumulations across a large portion of the state.
Several distinct periods of precipitation occurred across the state during this multi-day event, which has been broken down in the recap to follow. Marginal thermal profiles and surface temperatures during this period kept snowfall totals in check...from being much higher, as is usual mid-winter setup. Additionally, due to the fact that accumulating snow came in several periods, melting occurred between these said period due to the aforementioned marginal surface temperatures.
Wednesday afternoon-Thursday afternoon...
An initial area of generally light snow moved across much of Northern, Central and Southwest Illinois, Wednesday evening into Thursday afternoon. Upwards of a dusting to 2" of snow occurred across much of Northern, Central and Southwest Illinois during this time. Thursday afternoon-Friday morning... A renewed push of precipitation spread across the state Thursday afternoon into Friday morning. Precipitation was predominately snow across Northwest, Western and Southwest Illinois...With mostly rain across Northeast, Eastern and Southwest Illinois. Upwards of 1-3” occurred during this time across Southwest, Western and Northwest Illinois...with amounts tapering to a dusting east of these areas.
Friday morning-Friday evening...
While light snow showers and flurries occurred across Northwest, Western and Southwest Illinois, with light rain showers and drizzle having occurred across Northeast, Eastern and Southwest Illinois. Friday evening-Saturday afternoon... Yet another renewed push of precipitation developed, and pivoted across Northern and portions of Central Illinois, Friday evening through Saturday afternoon. Light to moderate snow was common during this time, with brief periods of heavy snow. Upwards of 2-5" of snow occurred across a good portion of Northern Illinois during this time, with isolated higher amounts across far North-Central Illinois near the Illinois/Wisconsin border. Amounts tapered across Central Illinois on up into the Chicago area, to a dusting to 3".
Final multi-day cumulative storm snowfall totals of 2-6" occurred across much of Northern, Central and Southwest Illinois, with locally higher amounts of 6-8" across North-Central Illinois, near the Rockford area. Snowfall amounts tapered to a dusting to 2" from Chicago down into Eastern and Southern Illinois.
Below is a map representation of final snow and rain totals across the state and adjacent areas. 
(10:30PM - 1/24/20) A brief update regarding the wither storm that continues across the state tonight...
A large are of precipitation changed from rain to snow across Northern Illinois this evening. Light to moderate snow is now ongoing for most affected areas, with upwards of a dusting to 2" of snow accumulation so far tonight for many areas. This area of snow is expected to pivot through Northern Illinois over night, and into Saturday morning. Additional snowfall accumulation of up to a few to a couple of inches in likely during that time. Final snowfall totals from tonight/tomorrow alone will be 2-5", which when combined with the 1-2" that occurred Wed-Thur, with make for final storm snowfall totals of 3-6"...with locally higher amounts possible. 
Jan 22nd-25th Winter Storm Update: Shovelable Snow Likely Overnight Across Portions Of Illinois1/24/2020
Outside of some areas of fog and drizzle, mostly quiet and cloudy conditions are the norm across the state right now as the upper level low and associated low pressure system at the surface continues to slowly meander its way through the state. More accumulating snow is expected later tonight and overnight. The latest follows below....
Taking a look at current radar across the region this afternoon, we can see that the brunt of the activity is off to our east across portions of Michigan, Indiana, and Ohio and this is the area to watch as this precipitation should continue to be pulled back/curl northwest into the northern portions of the state later tonight and overnight.
Below is an animation of the evolution of the snow across the northern portions of the state tonight. Precipitation will curl back northwest into northern Illinois and then changeover to snow across a fairly wide area of northern Illinois as you can see below. Snow will then continue in a light to moderate intensity with embedded isolated areas of heavy snow into tomorrow morning. Snow showers then could continue into tomorrow afternoon but accumulations will most likely slow or stop completely by morning as surface temperatures warm.
We have not changed our thinking is expected snowfall totals and these amounts are the multi day totals from when the event began on Wednesday.
(7:00AM - 1/24/20) What seems to be a never ending pattern we are stuck in recently, yet another late week/weekend winter storm is affecting state, and will continue to through Saturday. This storm system will be of long duration, with light to moderate accumulations of wintry precipitation are likely across a large portion of the state.
Synopsis...
A complex setup has been unfolding across the region, and will continue to into the weekend. Several upper air disturbances moving through the region will interact with each other during this time. The result has been the development of a storm system, which is looping through the region. During this period, an extended period of precipitation is likely across the state, through Saturday. Wintry precipitation will be favored for much of Northern and Central Illinois for most of this period, with rain more likely across Eastern and Southern Illinois. Observations continue to support the going forecast.
Wednesday afternoon-Thursday afternoon...
An initial area of snow moved across much of Northern and Central Illinois, Wednesday evening into Thursday afternoon. Upwards of a dusting to 2" of snow occurred across much of Northern and Central Illinois during this time. Thursday afternoon-Friday morning... A renewed push of precipitation spread across the state Thursday afternoon and evening, and continues this morning. Precipitation has been predominately snow across Northwest, Western and Southwest Illinois...With mostly rain across Northeast, Eastern and Southwest Illinois. Upwards of 1-3” occurred during this time across Southwest, Western and Northwest Illinois...with amounts hampering to a dusting east of these areas.
Friday morning-Friday evening...
While light snow showers and flurries will be possible across Northwest, Western and Southwest Illinois, light rain showers and drizzle will be possible across Northeast, Eastern and Southwest Illinois. Friday evening-Saturday afternoon... Yet another renewed push of precipitation is likely to wrap into Northern an portions of Central Illinois Friday evening through Saturday afternoon. This activity may start as a bit of rain, before changing over to snow. A period of moderate to heavy snow will be possible during this time, especially across Northeast Illinois. Snowfall accumulations of 2-5" will be likely across portions of Northern Illinois during this time, tapering to a dusting to 2" across Central Illinois. Below is a map featuring estimated times precipitation will be ending on Saturday. This visual representations will be much better than several sentences of text, which gets confusing. 
Final snowfall totals are expected in the 3-6" range across much of Northern and Central Illinois, with amounts tapering south and east from there. Locally higher amounts of snow will be possible across Northern Illinois. Minor sleet/ice accumulations will be possible as well, across Central and Southern Illinois.
Below is our TAM snowfall forecast for this event. 
(9:00PM - 1/23/20) What seems to be a never ending pattern we are stuck in recently, yet another late week/weekend winter storm is affecting state, and will continue to through Saturday. This storm system will be of long duration, with light to moderate accumulations of wintry precipitation are likely across a large portion of the state.
Synopsis...
A complex setup has been unfolding across the region, and will continue to into the weekend. Several upper air disturbances moving through the region will interact with each other during this time. The result has been the development of a storm system, which is starting to loop through the region. During this period, an extended period of precipitation is likely across the state, through Saturday. Wintry precipitation will be favored for much of Northern and Central Illinois for most of this period, with rain more likely across Eastern and Southern Illinois. Model guidance continues to be in fairly good agreement regarding this period, with observations supporting. No real change is needed this update, other then to mentioned the possibility of localized higher snowfall amounts being possible across Northern Illinois, as confidence continues to grow.
Wednesday afternoon-Thursday afternoon...
An initial area of snow moved across much of Northern and Central Illinois, Wednesday evening into Thursday afternoon. Upwards of a dusting to 2" of snow occurred across much of Northern and Central Illinois during this time. Thursday afternoon-Friday morning... A renewed push of precipitation has spread across the state this afternoon and evening. Precipitation has been predominately snow across Northern, Western and Southwest Illinois...With mostly rain across Eastern and Southwest Illinois. Precipitation will continue to move across the state overnight and into Friday morning. Snow will continue to be the main precipitation type across Northwest, Western and Southwest Illinois. Across Northeast Illinois, snow will eventually range to a mix or rain late tonight or early Friday morning. Rain continue to be the main precipitation type across Eastern and Southwest Illinois. Upwards of a dusting to 3" of snow will be likely during this time across Northern, Western and Southwest Illinois, with locally higher amounts possible in Western Illinois.
Friday morning-Friday evening...
While light snow showers and flurries will be possible across Northwest, Western and Southwest Illinois, light rain showers and drizzle will be possible across Northeast, Eastern and Southwest Illinois. Friday evening-Saturday afternoon... Yet another renewed push of precipitation is likely to wrap into Northern an portions of Central Illinois Friday evening through Saturday afternoon. This activity may start as a bit of rain, before changing over to snow. A period of moderate to heavy snow will be possible during this time, especially across Northeast Illinois. Snowfall accumulations of 2-5" will be likely across portions of Northern Illinois during this time, tapering to a dusting to 2" across Central Illinois. Below is a map featuring estimated times precipitation will be ending on Saturday. This visual representations will be much better than several sentences of text, which gets confusing.
Final snowfall totals are expected in the 3-6" range across much of Northern and Central Illinois, with amounts tapering south and east from there. Locally higher amounts of snow will be possible across Northern Illinois. Minor sleet/ice accumulations will be possible as well, across Central and Southern Illinois. Final snowfall totals will include several periods of snow over the multi-day period. It should be noted that given marginal surface temperatures during this period, there will be a constant/slow melting of snow. So what is on the ground after the event ends, will end up being less that what falls/accumulates during the event.
Below is our TAM snowfall forecast for this event. 
Our slow moving winter storm made its initial presence known overnight last night into this morning with areas across western and northern Illinois picking up 1-2" of snow so far with a few isolated spots in western Illinois getting up to 3". We will see a lull in activity later this afternoon and into the evening but model guidance continues to highlight another period of good snows later tonight and overnight as you'll see below. Let's dig into the latest....
As we have tracked our system from well out across the Pacific Ocean to coming ashore and crossing the Rockies, we can now say it is on the door steps of entering the Midwest this afternoon. Our upper level low is slowly organizing and strengthening as it comes further into the region this afternoon. It will eventually turn more east then northeast and take a favorable track for widespread accumulating snows across portions of the state.
Taking a look at regional radar this afternoon, there are a couple areas of scattered snow showers across the state (in orange) and down into portions of Missouri with more rain being the norm across southern Illinois. Besides some passing areas of light snow over the coming hours, we will be mostly void of more widespread precipitation till later tonight and overnight. Also plotted on there is the current position of our weather system by the red L along with the forecast track it is going to slowly take over the next 36-48 hours.
Below is a high resolution model animation of pretty much the duration of this event from 2pm this afternoon through Saturday evening. This really shows the slow moving nature of this winter storm and the areas of darker blues indicative of heavier snows pin wheeling around the area of low pressure as it meanders across the Midwest. We will see a lull in good snows later today and this evening but more organized snows will develop later tonight and overnight across central Illinois then pin wheel their way north and northwest into western and northern Illinois overnight, dropping another 1-2" locally 3" of snow by tomorrow morning. Tomorrow is a little trickier but some areas across western and northern Illinois could remain all snow through much of the day but accumulation rates could slow down given marginal surface temperatures. Further east across east central and maybe into the southern suburbs of Chicago near I-80, there could be a changeover to rain or a mix for a time tomorrow afternoon.
The real interesting period ot watch is tomorrow night through late Saturday morning where latest model guidance continues to mostly be in good agreement on a better chance of more substantial snow accumulations across the northern part of the state as a good slug of moisture wraps around the low pressure system into the area. 
Below is our latest thinking on total snowfall amounts. Stay tuned for continued updates on this slow moving winter storm.
(7:00AM - 1/23/20) What seems to be a never ending pattern we are stuck in recently, yet another late week/weekend winter storm will affect the state, through Saturday. This storm system will be of long duration, with light to moderate accumulations of wintry precipitation are likely across a large portion of the state.
Synopsis...
A complex setup is unfolding across the region, from now on into the weekend. Several upper air disturbances moving through the region will interact with each other during this time. The result will be the development of a storm system, which will loop through the region. During this period, an extended period of precipitation is likely across the state, through Saturday. Wintry precipitation will be favored for much of Northern and Central Illinois for most of this period, with rain and a mix more likely across Eastern and Southern Illinois. Model guidance continues to be in fairly good agreement regarding this period, with early observations supporting. No real change is needed this update.
A large area of snow is ongoing over much of Northern and Central Illinois this morning, with mixed precipitation and rain across Southern Illinois. Upwards of a dusting to 2" of snow has occurred across Northern and Central Illinois thus far. Precipitation is expected to continue across much of the state from this point right on into Saturday, before slowly ending. Much of Northern and Central Illinois has a good shot at seeing most of the precipitation during this period fall as snow, with only short periods of mixed precipitation or rain expected. Across Eastern and Southern Illinois, much of the precipitation will fall as a mix of precipitation and rain.
Below are maps featuring estimated times precipitation will be ending on Saturday. These visual representations will be much better than several sentences of text, which gets confusing. 
Final snowfall totals are expected in the 3-6" range across most of Northern and Central Illinois, with amounts tapering south and east from there. Minor sleet/ice accumulations will be possible as well, across Central and Southern Illinois.
Below is our TAM snowfall forecast for this event. 
Conditions continue to remain quiet across the state with just widespread cloud cover right now but precipitation is slowly moving towards the state this afternoon. Our confidence continues to increase on widespread snow accumulations occurring across a large portion of the state over the next couple of days. Let's dig into the latest below.
Our system is slowly but surely organizing as it crosses the Rockies this afternoon and will then continuing to dive southeast into the plains later this evening, eventually turning and coming into portions of the Midwest. This sort of path is usually a favorable one for accumulating snows into portions of the state and that's exactly what we are going to see.
Taking a look at regional radar this afternoon, we can see a large area of mostly light precipitation in the form of snow and a mix, is ongoing across portions of Iowa and Missouri. This will continue to slowly spread eastward towards and into Illinois later today and more so tonight.
The animation below runs from noon today to 6pm on Friday, showing the evolution of the majority of this system, outside of the continued snow overnight Friday into Saturday. This period continues to look like that will be the time for better accumulations across the northern portion of the state. We are also still watching on a period Friday morning and afternoon where some areas flip to a mix or plain rain across portions of northeast and east central Illinois due to a warm layer aloft just above freezing.
Below is our latest expected snowfall totals from tonight into Saturday morning of this long duration winter system. As you might've noticed, we continue to slowly expand the 3-6" area as confidence continues to increase on widespread snow totals in that range. Stay tuned for continued updates though!
Our long duration winter storm is slowly inching closer and will begin to make its presence known across the Midwest and here in Illinois later tonight with snow moving into portions of the state. This system will be affecting us here through Saturday morning so even though there could be some breaks in activity across some areas, other areas could see continuous precipitation, possibly in the form of snow for over 48 straight hours. As you'll see below, this system is going to produce a widespread area of shovelable snow.
Per usual, let's take a look at where our system is this morning and the track it's going to take. At this time, it has pretty much fully come ashore and is kind of unorganized at the moment across portions of the Pacific Northwest and into southwest British Columbia in Canada. It will continue mostly east, crossing the northern Rockies and then diving more southeast into the northern and central plains tomorrow morning and afternoon, organizing and strengthening as it heads in our direction.
Just to start off, below is expected start times of precipitation across the state with the slow moving precipitation as it comes eastward with an animation of it following below.
The loop below runs from 6am this morning till noon tomorrow, showing the gradual spreading east of precipitation (mostly in the for of snow for Illinois). Much of the state today will be quiet and dry but look for mostly light snow to cross the river and enter Illinois later this afternoon and more so tonight into the overnight hours. Then, look for light snows to continue across a wide area into tomorrow afternoon and evening, favoring the northern half of the state with rain more likely downstate. Areas that remain all snow will receive 1-2" locally 3" of snow by late tomorrow afternoon and evening.
The above is just about the first half of this event as the animation below then runs from noon tomorrow through noon on Saturday, showing the very slow movement of this storm as it meanders across the Midwest. Areas of light to occasionally moderate snow will continue into Thursday night and Friday morning with some accumulations possible. As we head into Friday morning and afternoon, some model guidance, including the one below warm up the surface and low levels enough to make it so it changes to rain for a time. If that occurs, expect it not to be long lasting with rain changing back to snow Friday evening and continuing through overnight Friday into Saturday morning. This is the period we are watching for the heaviest snowfall rates and period that could produce some higher snowfall totals.
As mentioned yesterday, the expected snowfall totals below are what falls from late tomorrow night through Saturday morning and unlike the last system where all the snow fell in a short amount of time, this will be more drawn out with periods of light snow being the norm. It is also possible that the roads remain just wet and now snow covered given the marginal surface temperatures and all the accumulations will be on grassy and elevated surfaces.
Stay tuned for continued updates as the map below is subject to change as we continue to watch this system evolve. 
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