(9:30PM - 2/28/19) An active winter pattern will continue, with another winter storm set to impact the region and portions of the state Saturday evening through Sunday evening.

Model guidance continues to be in decent agreement regarding the track of this storm system, as well as with the snow axis and amounts. Snow will push into portions of Western and Southwest Illinois by Saturday evening, quickly spreading across portions of Central and much of Southern Illinois by early Saturday night. Snow will then continue in varying intensity through late Sunday afternoon, before ending from west to east Sunday evening.

Periods of moderate to heavy snow and 1" per hour snowfall rates will be likely at times. Snowfall accumulations will be widespread across Central and Southern Illinois, with the heaviest axis of 6-9" extending into Southwest Illinois, including the St. Louis metro area. Additionally, some sleet and freezing rain may be possible across far Southern Illinois. Minor accumulation of sleet/freezing rain is possible.

​Below is our first TAM snowfall forecast for this event.

JP

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Over the past 48 hours or so, model guidance slowly begun to come into more agreement on a potentially significant winter storm moving out of the plains and into portions of the Midwest and Illinois by the latter half of the upcoming weekend. There still remains plenty of uncertainty regarding track, strength, and expected snow amounts but confidence is increasing for a sizable snow event to hit portions of the state, beginning late Saturday evening and most of the day on Sunday. 

I dig into this potential winter storm below....

What has happened over the past few days or so is model guidance has trended further north with the main PV/upper level low across southern Canada, which then allows for this system to come ashore California and sneak across the heart of the United States. Essentially, the Canada upper level low is making more room for that system to cut across the plains and eventually into portions of the Midwest. Timing wise, this image is valid at noon on Saturday, showing our potential winter storm coming ashore the west coast. It is then forecast to move mostly in an easterly direction the rest of Saturday and into Sunday. 

As the system moves over the southern Rockies and into the southern plains, low level winds will strengthening, allowing for a favorable period of warm air advection and isentropic lift. This will aid in developing a widespread area of snow across the central plains by Saturday evening to our west, as you'll see below. 

Below is one models take on the evolution of this winter storm as it moves from the central plains into the southern Midwest, including what looks like the southern half of Illinois right now. The loop runs from Saturday afternoon through late Sunday night, showing a widespread area of snow streaking eastward into southern and central Illinois by late Saturday night. Right now, the period favored most for accumulations and heaviest snow looks to be Sunday morning through Sunday afternoon downstate with actual amounts still to be determined as we get closer. 

So, to sum things up....as things look right now, Sunday looks quite snowy across about the southern half of Illinois BUT things could and probably will change some between now and Saturday night/Sunday morning so be sure to stay tuned to continued updates over the next 48 hours or so. 

​Disregard the exact amounts on the image below for now and concentrate more the swath of highest snow totals as it looks like further downstate will see the most snow as of now. 

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(9:15PM - 2/27/19) A weak and fast moving disturbance will bring wintry precipitation or portions of the state tonight into Thursday evening.

Scattered freezing rain showers will be pushing into Southwest Illinois within the next few hours. This activity will push across much of Southern Illinois overnight and into Thursday evening, before exiting the state. Ice accumulation of a glaze to up to around 0.10” is likely. Additionally, some sleet/snow may mix in the further north you go in Southern Illinois, especially as you get closer to I-70. Only a dusting of sleet/snow is possible.

​Below is our TAM ice forecast for this event.

JP

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We continue to monitor the growing potential for a several day, significant cold outbreak across the Midwest, including Illinois that could produce near record cold temperatures. This would begin on Sunday as things look now and and continue into next week. Nothing is fore sure set in stone but model guidance continues to show the threat for brutally cold air invading our area during this time-frame. We are now getting into early March when temperatures are supposed to be warming up across the Midwest but some areas will see temperatures 30 degrees or more below what is normal for this time of year. As we have also mentioned, this isn't going to be a quick hitting shot of cold either as we could have a three to four day stretch of very cold temperatures across our area. 

I dig into the latest below on this expected cold outbreak...

Numerical model guidance continues to be in fairly decent agreement with continued consistency on very cold air coming down into our area from southern Canada and the northern plains by the latter half of the upcoming weekend. We are once again able to see this fairly easily in the loop below looking at temperatures around 5,000ft off the ground where there is no diurnal effect from the sun. If you look up over western Canada at the beginning of the loop, you can see the gray/white colors, indicative of very cold temperatures and that very cold air then working its way southeast into the northern plains and eventually our area by Sunday and Monday.  

The arrival of this cold outbreak will come Sunday morning with the northern half of the state or so seeing the coldest temperatures by this time. The image below shows forecast temperatures at 9am Sunday morning. As you can see, the heart of the really cold air hasn't made its way downstate yet. 

By the start of the work week next week, high pressure and the very cold temperatures will have moved in closer to us in Illinois and we can expect much more widespread brutally cold air statewide by Monday morning. Below is forecast temperatures at 6am on Monday morning with some areas potentially getting below zero. This is when some locations will see temperatures 30-35 degrees below normal. 

If you're looking for relief and a warm up by Tuesday, you will not get it. This very cold outbreak looks to roll on right into and through the day on Tuesday with temperatures once again getting down into the single digits and even below zero for some on Tuesday morning across the state, shown below. 

We won't show you expected temperatures for Wednesday (morning) just yet as some models continue the cold outbreak into the middle of next week while others finally have it subsiding. But either way, the point to get across is that this is going to be a several day event of extremely cold temperatures across the Midwest and Illinois for early March. The Climate Prediction Center continues to outline a very large area, centered on the Midwest, for well below normal temperatures for early next week, shown below. 

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(10:00PM - 2/25/19) Evening update on the light snow event for portions of the state from tonight through Wednesday afternoon.

A combination of multiple disturbances moving through the region, warm air advection and frontogenesis...will bring the chance for periodic snow showers and light snow to portions of Northern Illinois tonight through Wednesday afternoon. It should be noted that model guidance has been trending a bit drier with this event over time. This will be a minor event overall, with accumulations ranging from a dusting closer to I-80, to 1-3" closer to the Illinois/Wisconsin border.

Additionally, a bit of freezing drizzle may be possible across portions of Northern and Central Illinois, between roughly I-88 and I-74. This will be possible Tuesday night into Wednesday afternoon.

​Below is our updated TAM snowfall forecast for this event.

​JP

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Unfortunately, this article isn't going to come as good news to a lot of folks and only the cold winter lovers will like this but we are looking at a potentially very impressive cold outbreak across the Midwest, one that could also break some records as well. This doesn't look to be a one day event either as we could see a stretch from this coming Sunday to the middle of next week of very cold to near record breaking cold temperatures across portions of the region, including here in Illinois. Now, of course we are many days away from this but given there is good model agreement at this stage of the game, we wanted to give people an early heads up, especially those who think that once the calendar turns to March, warm weather returns. That is definitely not going to be the case this year.  

I dig into some of the early details below

The rest of the week will be chilly and cold for the most part with a continued active look as well with several disturbances leading to snow chances between today and Friday. It is after a potential bigger system on Friday that the cold flood gates open up and much colder temperatures invade the Midwest, including here in Illinois. You're able to see this in the loop below, showing temperatures at 850mb, or 5,000ft, moving southeast into the region by Saturday afternoon and more so on Sunday. The loop itself runs from Friday afternoon all the way through next Wednesday night. With this long loop, you're able to visually see the staying power of this brutally cold air for early March. The purples, whites and grays are the very cold temperatures. 

As things look now, and this could easily change but the coldest days look to be Sunday and Monday and these are the mornings that could potentially flirt with record lows across portions of the state. Below is forecast temperatures valid at 6am this coming Sunday. 

Now here is forecast temperatures across the Midwest and Illinois on Monday morning. This is a favorably synoptic setup with a large surface high off to our east, allowing for both clear skies and also some cold air advection given the northwest winds to aid in advecting that very cold air into Illinois. So as you can see, there could be back to back mornings with temperatures below zero for portions of the state.  

Lastly, I wanted to include the 6 to 10 day outlook from the Climate Prediction Center as this is their outlook centered on the time-frame being talked about in the article. As you can see, very cold and well below normal temperatures are expected across a wide area over the United States, all the way from the Canadian border down into Texas, with Illinois centered smack in the middle. 

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We continue to eye the threat of accumulating snow across portions of northern Illinois, beginning tonight and through Wednesday morning and coming in what looks like two separates waves. This will not be a continuous event or a big snow maker and there will be fairly large breaks in the snow but several smaller disturbances passing through the Midwest will lead to increased chances for snow and snow that could accumulate across portions of northern Illinois. 

I dig into the latest below, including trying to pin down the timing of these several waves of snow....

Latest high resolution model guidance continues to suggest that snow will develop over portions of northern Illinois late tonight and overnight, possibly snowing into the early morning hours. This developing snow will be associated with an area of frontogenesis aloft, leading to a narrow band of snow. There could also be some lake effect snow showers across northeast Illinois tomorrow morning. The loop below runs from 9pm this evening till 11am tomorrow. 

The area outlined in orange below stands the best chance for a dusting to possibly just over an inch of snow by tomorrow morning. 

The next bout of possible snow will come tomorrow evening/late tomorrow night brought on by a period of warm air advection and isentropic lift. Model guidance continue to differ some on the placement of this band of snow with some keeping it across northern Illinois while other guidance has it further north into Wisconsin. 

Below is our current thought on expected snowfall totals between both periods of snow....the one late tonight into tomorrow morning and the second one tomorrow evening and late tomorrow night. Each of these will have the potential to produce a half inch to 1.5" of snow, most likely in a fairly narrow band. Right now, we are favoring far northern Illinois for the highest totals. 

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(10:30PM - 2/24/19) A new series of disturbances will bring the chance of snow to portions of the state from Monday night through Wednesday afternoon.

A combination of multiple disturbances moving through the region, warm air advection and frontogenesis...will bring the chance for snow to portions of Northern Illinois Monday night through Wednesday afternoon. While light snows will be possible during the whole period, the most organized snows will be late Monday night through Tuesday morning, and then once again Tuesday afternoon through Wednesday morning. This will be a minor event overall, with accumulations ranging from a dusting closer to I-80, to 1-3" from around I-88 to the Illinois/Wisconsin border.

Additionally, a bit of freezing drizzle may be possible across portions of Northern and Central Illinois, between roughly I-88 and I-74. This will be possible Tuesday night into Wednesday afternoon.

​Below is our TAM snowfall forecast for this event.

​JP

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(2:30PM - 2/24/19) Check out those tightly packed isobars on the surface plot! Those lines represent equal pressure gradients around a deepening storm system over the Great Lakes. This has lead to damaging wind gusts across all of the Great Lakes region, including Illinois.

The damaging wind event continues for portions of the state at this time, but will gradually end this evening and tonight...

High winds have been impacting much of the state from late night through now. Widespread wind gusts of 50-65MPH have occurred across much of the state during that time, with isolated higher gusts. Numerous reports of tree and structural damage, along with power outages, have been coming in from Northern and Central Illinois.

Winds have already gradually lessened across Southern Illinois, and will continue to do so. Winds across Central Illinois will lessen heading into the evening, and across Northern Illinois early tonight. Until those times, wind gusts of 50-65MPH will continue to be likely.

High Wind Warnings remain in effect until 7pm. 

(2:15AM - 2/24/19) The expected high wind event has started for portions of the state, with windy conditions to spread across the rest of the state the next several hours...

Over the last few hours high winds have spread across portions of Central and Southern Illinois. St. Louis has has recorded a wind gust of 66MPH and Springfiled 61MPH, so far with this event.

Windy conditions will spread across the remainder of Central and Southern Illinois the next few hours, then continuing into Sunday afternoon. Across Northern Illinois, winds will also move in over the next few hours, then persisting into early Sunday night.

Max wind gusts across much of the state will peak at 50-60MPH, with localized gusts of 60-70MPH possible. Some tree damage and power outages can be expected for some areas.

Below is our updated TAM wind forecast for this event.

JP

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