(10:00AM - 10/26/19) The combination of Tropical Storm Olga and a storm system merging across the region will bring heavy rain, flooding and windy conditions to portions of the state this weekend.
A disturbance and associated storm system is currently pushing across the Southern Mississippi Valley. Additionally, the remnants of Tropical Storm Olga are also pushing northward across the Southern Mississippi Valley. The storm system and Tropical Storm Olga are expected to phase together today. The outcome from this will be a well organized storm system, which will lift northward and track up across Illinois and Indiana into tonight.
High moisture content characterized by PWAT's of 1.00-1.90" will be pulled northward and into the region, courtesy of Tropical Storm Olga. This will lead to heavy and efficient rainfall, with widespread rainfall totals of 1-3" likely across much of the state...the exception being far Western and Northwest Illinois, where rainfall totals will remain well below 1.00". Locally higher amounts of 3-5" will be possible across portions of Central and Southern Illinois. The heavy rain and expected high rainfall totals will likely lead to minor to moderate flood potential for some areas, with Central and Southern Illinois being at greatest risk for this for flooding. A large area of heavy rain has already spread across Southern and Central Illinois last night and this morning. Rain will overspread much of the state by afternoon, continuing through the day, before gradually ending from southwest to northeast across the state this evening into tonight.
Windy conditions are likely across the state as well, as the storm system becomes more organized and strengthens after the aforementioned phasing of systems occurs. Wind gusts of 20-45MPH are likely across a good portion of the state later this morning through early Sunday morning. A corridor of wind gusts in excess of 50MPH will be possible across Southeast and Eastern Illinois, closer to the track of the storm system.
Below is the TAM flood and wind forecasts, through early Sunday morning.