Major Winter Storm With Heavy Rain, Flooding, High Winds And Severe T’Storms Expected Late Week/Weekend (Thur-Sat, Jan 9-11th)

(7:30AM - 1/9/20) A complex scenario is expected to unfold across the region in the coming days, with a few disturbances and then a main storm system expected to push across the region. During this period all of the following will be possible across the state... Snow, ice, sleet, heavy rain, flooding, high winds and severe t'storms. This post will be directed towards the heavy rain, flooding, high wind and severe t'storm aspect. For information regarding the snow, sleet and freezing rain threat...please read the update at the following link: https://www.illinoisstormchasers.com/forecasts/major-winter-storm-with-snow-sleet-ice-and-high-winds-expected-this-weekend-fri-sun-jan-10-12th

Thursday morning-Friday morning...
A lead disturbance will push across the region today. Along with this disturbance will come the chance for scattered showers across the state during this time, with perhaps more organized and widespread areas of rain across Central and Southern Illinois tonight into Friday morning. In addition to the rain, increased winds are expected this morning into tonight, with wind gusts of 25-40mph are likely across the state. Atmospheric mixing depths are expected to me low...However, should deeper mixing occur, higher wind gusts in excess of 40mph would be possible. Rainfall totals during this period will likely be less then 0.50" for much of the state, the exception being portions of Central and Southern Illinois, where an area of rainfall totals in excess of 0.50" are possible.

Friday afternoon-Saturday night...
As a second disturbance and the main storm system eject out through the region, more organized, widespread and heavier rain and isolated t'storms will develop and spread across the state from Friday afternoon into Saturday afternoon. Training of heavy rainfall is possible for a time across the heart of the state. With a strong storm system, strong jet stream, and ample Gulf moisture advecting in from the south, an axis of high rainfall totals is expected across the region. Rainfall totals during this period will likely range from 1-4" across much of the state. Lingering scattered showers may continue across portions of Eastern and Southern Illinois Saturday evening into Saturday night.

High winds are also likely for portions of the state Friday evening through Saturday evening. Wind gusts of 25-50mph are likely across much of the state during this time, with the potential for isolated higher wind gusts.

Lastly, there will be a severe t'storm threat across Southern Illinois Friday evening into Saturday afternoon. With the aforementioned strong storm system moving through and associated dynamics in place, unseasonably warm temperatures, high moisture levels for this time of year, and some instability in place....A lower end severe t'storm threat is likely. A fast moving broken line of t'storms will likely sweep across Southern Illinois during this time-frame. Given the environment expected to be in place, damaging winds will be the main threat, though an isolated tornado cannot be ruled.

Final overall rainfall totals during this multi-day period will likely range from 2-5" across much of the state. Given the expected high rainfall totals over a relatively short period of time, widespread low to moderate flood potential exists across much of the state.

Below are the TAM flood, wind and severe t'storm forecast for this period.

JP

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