(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.
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.
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