Major Winter Storm With Heavy Rain, Flooding, High Winds And Severe T'Storms Late Week/Weekend (Thur-Sat, Jan 9-11th) Update #5

(10:30AM - 1/10/20) A complex scenario is unfolding across the region, 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, sleet, ice, 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 aspect...please read the update at the following link: https://www.illinoisstormchasers.com/forecasts/major-winter-storm-with-snow-sleet-ice-and-high-winds-this-weekend-fri-sat-jan-10-11th-update-7​

**Based on model guidance and observations from last night and this morning, we have increased the flood risk and severe t'storm risk across portions of the state with this update**

Thursday morning-Friday morning...
A lead disturbance moved across the region on Thursday, bringing with it scattered showers and high winds that impacted much of the state. Rainfall amounts were on the light side, generally a trace to under 0.25" across the state. Wind gusts topped out in the 25-45mph range across much of the state. More organized and widespread areas of rain developed Thursday evening, which moved across Central and Southern Illinois last night on into this morning. Areas of rain continue to spread across Central and Southern Illinois at this time. Upwards of 1-3" of rainfall has already occurred across a good portion of Central and Southern Illinois with this activity.

Friday afternoon-Saturday evening...
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 this afternoon into Saturday afternoon. Training of heavy rainfall is likely 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 will continue across portions of Eastern and Southern Illinois Saturday afternoon into early Saturday night.

High winds are also likely for much of the state this evening through early Saturday night. Wind gusts of 25-45mph are likely across much of the state during this time, with the potential for higher wind gusts of 45-55mph across Southern and Eastern Illinois..

There will also be a severe t'storm threat across Southern Illinois from late this afternoon into Saturday morning. With the aforementioned strong storm system moving through and associated dynamics, unseasonably warm temperatures, high moisture levels for this time of year, and some instability in place....An isolated to scattered severe t'storm threat is likely across Southern Illinois. A broken line of t'storms will likely sweep across Southern Illinois during this time-frame. Given the environment expected to be in place, an isolated to scattered severe t'storm threat will exist... While all modes of severe weather are possible, damaging winds will be the main threat, as well as isolated tornadoes.

​Final overall rainfall totals during this multi-day period will likely range from 2-4" across much of the state, with an axis of 3-7" rainfall totals across portions of Central and Southern Illinois. Given the expected high rainfall totals over a relatively short period of time and training of heavy activity, widespread low to moderate flood potential exists across much of the state, with high flood risk across the harder hit corridor of portions of Central and Southern Illinois.

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

JP

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