Winter Storm Set To Bring Accumulating Snow/Sleet/Ice To The State Late Week/Weekend (Fri-Sat, Jan 17-18th) Update #6

(6:30AM - 1/16/20) A storm system will move through the region on Friday and Saturday, bringing with it a wide range of precipitation types across the state, including snow, sleet, ice and rain. Light to moderate accumulations of wintry precipitation are likely across a good portion of the state.
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Synopsis...
Model guidance has been and continues to be in decent agreement regarding this period. A storm system cutting generally west to east across the Midwest is expected, with accumulating snow/sleet/ice expected across a large portion of the region. Once again, there are minimal changes needed with this update. However, it should be mentioned that there has been a trend among model guidance for precipitation to stay as snow for a longer period of time across Northern Illinois. Should this trend continue, and look more likely, then an increase in expected snowfall amounts would be needed across this area. However, for now will not make changes and will stick with the going forecast, closely monitoring the situation.

Precipitation is likely to begin as snow as it enters Northwest, West and Southwest Illinois late morning or around midday Friday. As precipitation then spreads across the state Friday afternoon, a several hour period of snow to sleet to freezing rain will occur. This wintry mix will continue through the afternoon and into the evening, before precipitation transitions to rain across the state Friday night. 

By later Friday night, precipitation will have fully changed over to rain across just about the entire state. Rain showers will then continue into Saturday afternoon, before ending from west to east across the state. The exception will be across Northern Illinois, where rain showers will change back over to snow showers, before ending during the afternoon. Additional minor snow accumulation will be possible.

Below are maps featuring estimated start times of wintry precipitation on Friday, and then estimated times of the change-over to rain Friday night. These visual representations will be much better than several sentences of text, which gets confusing.

Final snow/sleet totals over much of Northern and Central Illinois will range from 1-4", with higher totals likely near the Illinois/Wisconsin border and far Northwest Illinois. Ice totals will likely range from a glaze to 0.15" across much of the state, though locally higher amounts will be possible across the heart of the state.

Below are the TAM snow/sleet and ice forecasts for this event.

JP

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