The well advertised winter storm is taking shape and should begin to slowly encroach the state as the day progresses. Most winter storm watches have been upgraded to winter storm WARNINGS as a result.
TIMING THE STORM:
Timing the storm is always difficult, but we'll use a couple hi-res models to illustrate the general timeline of how we expect the events to unfold.
By 1-3pm, a frontogenesis band of snow will begin to ooze in across northern Illinois. This will give these areas a jump start to the snow. Just how heavy this early band of snow will be is a current wildcard in the forecast. These snows can sometimes over-perform. There is also some guidance trying to hint this band forms farther north, but it looks like some of northern Illinois will get in on the action first.
By Friday evening, the main surface low will begin to approach to our south. The main band of snow will arrive with it. Snow should begin across western and central Illinois in the 5 to 8pm timeframe.
By Saturday morning, much of the state will be experiencing moderate to sometimes heavy snow falling. This will be the height of storm and should last through sunrise and into the early morning.
Snow will begin to taper off Saturday afternoon and early evening, first across northwestern Illinois, then western and central Illinois. The snow will gradually end as the system begins to pull away. Heavy snow will now be falling across parts of southern Illinois, but some rain/sleet may also mix in which should reduce totals in these areas.
Once the lake effect snow winds down late Sunday morning the event will be over for all. Our attention will then turn to another potential heavy snow maker to arrive Tuesday.
We expect the heaviest totals across northern Illinois, mainly due to getting in on the early action frontogenesis band of snow before the main system snow. Areas along Lake Michigan will see a double wild card bonus with that plus the lake effect band.
Winds will be another story with this system and could gust to 35mph creating near blizzard whiteout conditions. Travel is strongly discouraged Friday evening and much of the day Saturday. Below is out latest TAM (yes, some of the areas might not perfectly match up with the amounts on the map above - our TAM is a bit more of a high resolution forecast map as opposed to county warnings issued by the NWS.)
Stay tuned to ISC as we bring you updates throughout the day.
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