Updated Detailed SnowCast For Tonight. JT. #ILWX #INWX #OHWX

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Forecast Discussion:

CURRENTLY: An area of high pressure is in place across the region this morning allowing for very cold and calm conditions across the region. However, we are watching the developing area of low pressure across the southern Plains. This will be our focus for snow late tonight through Wednesday.


TONIGHT – WEDNESDAY: Looking at the latest model guidance we are seeing some northward shift in the snowfall forecast. While the overall snowfall forecast is coming north the most notable change comes in the upper levels at 500 mb. The 0z NAM that ran last night showed an upper level vorticity max that is placed across very southern Indiana/Kentucky.

Last Night’s NAM 500 mb

However, with each run the forecast models have brought that vorticity maximum farther north. This morning’s run of the NAM shows the main area of vorticity from the I-70 corridor south. This will be crucial to the overall snowfall forecast because the placement of the upper level vorticity maxima will greatly influence where the heavier snow will occur.

This Mornings NAM 500 mb
This Mornings NAM 500 mb

Regarding timing, snow looks to enter very western Illinois after 7-8 PM this evening and will spread eastward.


Through the evening the snow will work to the east. Likely entering western Indiana around 12-1 AM Wednesday morning. Areas of heavy snow will be possible at this point in time, especially across zone 6 & 7.

Snow will continue east through the night likely moving into the Indianapolis metro area around 2-3 AM Wednesday morning. At this point snow will still be ongoing across a large portions of Illinois and the western half of Indiana.


Through the overnight snow will move to the east across the region with snow ending across Illinois from west to east. By 6-7 AM Wednesday morning the main area of snow will be moving out of Illinois and western Indiana, while snow continues across the Indianapolis area and points east. With that being said, there still could be some light snow showers or flurries hanging around west of there.


Through mid-day the main area of snow will move off to the east of the forecast region. We will be watching another area of upper level energy move southeast through the region late morning through the afternoon. While the atmosphere will be pretty dried out from the morning system, this upper level disturbance may allow from some more isolated to widely scattered snow showers to form.


The latest NAM models have brought the heaviest snow farther north into southern Illinois and southwestern Indiana.


For now our forecast will remain the same. However, we will be watching this very closely today as more data becomes available, so make sure to check back as we anticipate changes!

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